35 ms·

Weird monitor bugs people sent me in the last 5 years

524 points by alin23 4y ago

weaksauce 4y ago
that install script is not correct. $BIN is never set to anything so it would thankfully crash at the mkdir -p instead of installing to the root directory but either way it wouldn't work
- alin23 4y ago
  Correct, thanks for catching that! I updated the post.
peanut_worm 4y ago
I had a monitor once with a built in speaker that would pick up random radio broadcasts. I don’t even understand how it happened.
lacoleman 4y ago
Wow... I started at my current job about a year ago and we use Mac Minis as the main workstation for the users. Well as the users started doing more work we got them dual monitors and that is when I started noticing the first problem described. Everyday the same few people would come to me saying that their display settings would swap the main monitor, and sometimes it happened when they went to lunch. I searched online and couldn't really find a sure-fire resolution. I did however, find that if I logged into the administrator account and swapped the monitors, then went into the Energy Saver settings and prevented the Mac from automatically sleeping when the display is off then it keeps the problem away long enough. I will usually have to repeat that process upon an update but I am just glad I found out why this was actually happening.
rjmunro 4y ago
It would be good if the article mentioned the models of buggy monitors, in particular those that don't present unique UUIDs, so that we know which ones to avoid buying. I'm about to choose a new monitor, they all seem much the same, but being reliable against this sort of problem would be a deal-winner for me.
- alin23 4y ago
  Author here. All vendors do this, it's not only on specific models. The only way to surely avoid this is to buy different types of monitors.
tinus_hn 4y ago
For an example of monitor firmware quality: https://news.ycombinator.com/item?id=32634467 https://news.ycombinator.com/item?id=32634467 Hacking your (Dell 2410u) monitor through ddc
bombcar 4y ago
So many monitors run on similar controllers internally - it would be absolutely wonderful if one or more of those had open source firmware so these bugs could be fixed
- rootusrootus 4y ago
  Would also be wonderful if they could use a halfway modern CPU so the monitor didn't take 30 seconds to wake up. My CRG9 takes long enough that my macbook will fall asleep again from the password prompt as I'm waiting for the monitor to light up, if I don't keep hitting keys.
  - dbttdft 4y ago
    It's a bug with most modern LCDs. Ever since HDMI days they started taking ages to turn on or change modes. I have LCDs from 1997 that turn on and change modes in about 100ms, as opposed to the new 3s-10s. I suspect something extremely stupid, like maybe HDCP crap takes a long time to do its thing (regardless of whether its used) and the process gets blocked on that.
  - staindk 4y ago
    That thing looks fancy! Perhaps make sure there isn't a "light sleep" or similar option in its OSD that allows it to blank the screen without fully sleeping. On my monitor (~5ish year old Dell) I have the "Deep Sleep" option disabled and it suits me very well like this.
    - rootusrootus 4y ago
      That's a good catch. There is an 'eco saving' setting that I found after you mentioned it, and it does seem to help the monitor wake up faster. Still not going to win any speed contests, but waking up before the computer goes back to sleep is a win!
  - smilespray 4y ago
    I have the same monitor (and a mac), and it sure does take a long time to wake up. I found that disabling all forms of eco saving and deep sleep settings will make the monitor wait for the Mac when waking up. I no longer have to keep hitting keys. It still takes a while to wake up, but at least it's predictable.
swayvil 4y ago
- davzie 4y ago
  The AI comments are getting out of hand
  - samarthr1 4y ago
    How can you tell that it was an AI post though?
    - swayvil 4y ago
      No human would use allcaps italics like that.
      - bredren 4y ago
        Also: “sent it to a tech”
        oyashirochama 4y ago
        When the AI is cringe.
        deleted 4y ago
        [deleted]
        swayvil 4y ago
        What's the preferred term? Boffin?
      - robocat 4y ago
        Could you give us a slice-of-life description of your AI life? Preferably without the violent or sexual aspects?
    - 4y ago
BIKESHOPagency 4y ago
This is a kind of look behind the curtain that we rarely get from large software developers. Users are often told by someone down the chain in support it works or doesn't and no explanation why. I find this very fascinating and as a saas developer that makes an app that has to work with external hardware that I often don't have to test on very encouraging. Sometimes, there's no fix and it's not my fault.
- alin23 4y ago
  I'm also moving towards software that is less dependent on hardware especially because of the headaches that Lunar brought me over the years. You're probably in a much better spot, SaaS is still the best way to make money as a developer, if you don't have to provide too much support.
  - alluro2 4y ago
    That "if" does a lot in that sentence :) Just had a typical fun experience: Customer: Your platform doesn't work, when we do this, A happens Me: Hm, we don't have that feature, but I understand your use-case. We could deliver this new feature by tomorrow, but using it that way also inherently means B would happen in such and such cases, so just want to make sure that's what you want? Customer: Let us know when the bug has been fixed, it's urgent and we're losing money because of you (they had 1 month free trial) Me:: It's not a bu...okay, we will Me: * works all night, builds a new feature, fully polished, notifies customer Customer after 2 days: Yet ANOTHER bug with your unstable software!! * describes B
    - alin23 4y ago
      Oh.. that sounds so familiar it almost triggers PTSD-like symptoms inside me. I guess these vocal and demanding people are everywhere, no matter how easy and intuitive the software is. I just had someone ask for a new feature and a discount on my $6 app a few minutes ago. We have to come to terms that this is part of the job where we have such a close connection to the people that use our product.
    - 4y ago
colechristensen 4y ago
I had a very strange monitor bug a few years ago. Dwarf fortress and a weird linux display mode drove my monitor to display a freeze frame of what was going on during the bug at about half opacity with a bit more of a glitchy feel. It stayed after reboot, mode changes, OS changes, retriggers of the bug etc. etc. etc. to the point where it did not make sense at all how the pseudoimage stayed past power cycles and everything else I could imagine. I briefly, and quite seriously, questioned my sanity trying to figure out what was going on. Eventually it just went away. Some firmware bug got an image stuck in memory or something, but man it was weird.
- solarengineer 4y ago
  I wonder if keeping the display powered off and disconnected from power supply for a minute or more would have helped in your case. I have run into not-so-funny situations due to capacitors. See https://dynamicproxy.livejournal.com/46862.html https://dynamicproxy.livejournal.com/46862.html
  - colechristensen 4y ago
    I did everything I could imagine including long periods of disconnecting power and nothing changed, it was very weird.
- alin23 4y ago
  Author here, it happens right now with my 5 year old LG 27UD88. When the bottom part of the monitor renders something darker (say a Sublime Text window), it also displays a ghost image of a lighter previous image (like the browser window with a white page). It started about a year ago, and every time it happens, the bottom part of the panel is very hot to the touch. After letting a fan blow over that part to cool down the LEDs behind, the problem went away. Which leads me to think this is a hardware problem, and the panel is giving up on me.
avian 4y ago
> Blacking out [...] unplug the power cable, and plug it back again As someone with a monitor that's prone to blacking out like this (not due to Lunar) and was at one point convinced that the monitor got bricked: the key is waiting ~5 minutes before plugging the power back in. A quick unplug-plug in a hurry might not do it. You need to wait for the internal capacitors to discharge to the point where the controller gets properly reset.
- alin23 4y ago
  Yes, that's a good hint. Most monitor power bricks have very large capacitors, especially when they also charge the laptop through the Thunderbolt connection. That's also the point of the LEDs you see on power bricks. After unplugging, the LED uses up the capacitor current to discharge them faster and also serves as a visual indicator to know when it's safe to plug back the cable.
- sroussey 4y ago
  Leaving the power off for 5min also has the advantage of cooling the machine.
- epakai 4y ago
  I have some dells (U2414H) that can get into a really bad state. Sometimes unplugging power is not enough. You have to remove all potential power inputs including display input cables (or shut those devices down too) to get a proper reset.
  - tobyhinloopen 4y ago
    Funny, i have the exact same display and I’ve had it randomly not work multiple times. Only unplugging everything seemed to work. Happened maybe 5 times in the many years ive owned it
- stanmancan 4y ago
  Does pressing power while it’s unplugged expedite the process by attempting to draw power and emptying any capacitors in the process?
colordrops 4y ago
I've got a cablematters thunderbolt hub with two DP outputs connected to two LG monitors. They aren't exactly the same but it doesn't matter, as I'm using Xorg, which doesn't use EDID for layouts. It just uses the output names, which are DP-1, and DP-2, and sometimes the hub flips them. The only way I've found to "fix" this is to use Autorandr, which will update the layout based on the EDID, but the output names remain flipped. This is still an unsolved problem, because i3 uses the output name rather than physical position for where to put workspaces. My other laptop doesn't have an nVidia GPU and runs Sway/Wayland, which doesn't seem to have this issue. If anyone knows how to solve this I'd be eternally grateful. It's been driving me nuts for a year.
- pedrocr 4y ago
  If you switch from i3 to sway you can use the serial number instead of the port to assign outputs. I think these days it's usable with even the proprietary nVidia driver.
  - colordrops 4y ago
    Oh interesting, I understand that sway with Nvidia is developing quickly. I did read maybe less than a month ago though that it's still quite glitchy. Will look into it again.
teetertater 4y ago
Thanks for developing Lunar, I'm a happy user for over a year!
- alin23 4y ago
  Thank you for the kind message! Happy to hear you find it so useful :)
  - guiambros 4y ago
    Another +1 from a happy user! Thank you for developing it. I use several times a day, whenever I'm entering/leaving video calls, or depending if the site/app has dark mode. It's incredibly helpful and reliable!
    - izerik 4y ago
      Every site has dark mode :) https://darkreader.org https://darkreader.org
gonehome 4y ago
Nice overview of interesting bugs. I used to have a ton of issues with my MacBook Pro and thunderbolt monitor. These issues persisted through different MacBooks and monitors (we used the monitors at work and it was a work machine so I had a few). All of these issues finally went away after getting an M1 machine. Maybe a coincidence but fewer monitor connection bugs was one of the noticeable changes for me. Based on the article it might also be because I switched to the apple pro display? Though I can’t remember what happened first. Also off-topic, but this blog has beautiful style and typography.
- sroussey 4y ago
  I found that after I updated the firmware of the monitors, they worked almost perfectly. And to make them actually work perfectly, I connect them on different sides on the MacBook Pro (intel version still). Took way too long to figure that out.
- alin23 4y ago
  Thanks, glad you like the styling ^_^ And yes, it's very likely that most of your problems went away because you're using the Pro Display, as it has a much faster CPU than most monitor controllers on the market. Apple displays also support a proprietary USB protocol through which they can communicate with the Mac faster than through the DDC protocol which is still based on two-wire slowpoke I²C. That Apple Native protocol is also supported by Lunar for silky smooth brightness transitions, which is just not possible on DDC, unless the monitor has some kind of built-in fader.
hardcopy 4y ago
I found Lunar very helpful in a South facing apartment with floor to ceiling windows. Without Lunar I had to spend a minute adjusting each monitor, multiple times a day. It solved a problem I never experienced in a home with normal windows.
- alin23 4y ago
  That's also how Lunar started actually :) I got my first Mac + monitor setup in an apartment with the desk on a closed balcony. It was driving me crazy to press the fiddly LG joystick to get to the brightness menu all day long, so I can follow the ever changing ambient brightness. It's also why Lunar v1.0 only had sunrise/sunset based automatic brightness, not even hotkeys for adjusting the brightness manually.
tristor 4y ago
I wonder if there’s any resources that validate monitor DDC capabilities. It sounds like a lot of the issues are caused by bad monitor firmware
- voltagex_ 4y ago
  A company called EnTech does this. https://www.entechtaiwan.com/lib/softmccs.shtm https://www.entechtaiwan.com/lib/softmccs.shtm
bluedino 4y ago
Makes me think of the "common knowledge" that Macs don't work properly with external monitors. Fuzzy fonts etc
- kmeisthax 4y ago
  That's moreso because Apple has a Strongly Held Belief that UIs should never render at fractional scale factors. If it needs to be 150%, it will render a larger virtual desktop at 200% and then downscale. Contrary to Apple, monitor manufacturers have a Strongly Held Belief that monitors should all be one marketable resolution (e.g. 4K) and shape (16:9 widescreen or wider) and users just pick a size. Bigger monitors shouldn't have more pixels in them. The Apple philosophy says that 4K 27" monitors are fundamentally broken hardware that the OS needs to fix at the cost of some display clarity. The manufacturer philosophy says that DisplayPort can't run 5K off a single cable[0] and that nobody wants letterboxing when watching a movie on their new laptop. Apple designs the monitor around what the OS and user need while display manufacturers design around whatever they can buy and repackage. Of course macOS has fuzzy fonts even at 1x, but that's not a display problem. That's a different Strongly Held Belief. Microsoft deliberately bends fonts to fit the pixel grid (they call this ClearType) while Apple uses antialiasing to remain faithful to the glyph shapes as they were originally designed. [0] Or at least this was true as of the release of the iMac 5K almost a decade ago. This is not true anymore but no manufacturer is touching 5K anyway.
  - politelemon 4y ago
    This is typical but poor gymnastics which grants benefit of the doubt to brand loyalty. Manufacturers hold no such belief, they are beholden to standards to cater to a wide variety of configurations and setups. Implying it's not made for users is poor form, and simply false.
    - jahewson 4y ago
      If this were true then companies other than Apple would offer monitors that actually do cater to non-broken configurations but they don’t. The parent post does a great job explaining the technical trade-offs and economy of scale optimisations that manufacturers have decided to make, whereas you have only an ad-hominem attack to offer.
mort96 4y ago
The first issue, where multiple monitors have the same vendor/model/manufacture date/serial number, couldn't that be solved by also storing which port it's connected to? That way, if you have two HDMI ports, if both monitors have the same UUID, you store settings based on port rather than UUID. I don't know if this is possible with this new USB-C world, but at least with traditional hardware, it seems like the OS knows which port a monitor is connected to. Anyways, interesting post. It's always fun to discover how much hardware is just broken and doesn't actually correctly implement the protocols or features it's supposed to implement.
- erichdongubler 4y ago
  This should be at least theoretically possible -- in Windows, for instance, device file paths are based on connection topology, including port address.
- feifan 4y ago
  Back when I had two monitors, I got the same cables for both and I indiscriminately plugged them into my computer (I had a laptop, so plugging/unplugging happened ~daily). So the mapping between computer port and monitor definitely wasn't going to stay the same.
  - mort96 4y ago
    Yeah, it would be a workaround for some cases but not all. It would work in the case of a desktop system where the monitors are always plugged in, and it would work for the case where the monitors go through some kind of USB-C dock (assuming it's possible), but not in your case.
  - tonyarkles 4y ago
    Not as convenient but you could label them, if the port was actually factored in.
  - Nition 4y ago
    You wouldn't use the "which port was it in last" fallback option unless you already had multiple saved entries where every other bit of data matched.
Karliss 4y ago
The first issue should be possible to deal with at OS level. Even if all the monitors send same serial number, OS should know in which port they are plugged in. Preferably things shouldn't swap if you swapped ports for your two monitors with properly unique serial numbers. But if the serial numbers are identical, ports seem like reasonable fallback since most people with multimonitor setups don't randomly unplug and plug them too often (except laptops).
- dt2m 4y ago
  Thought the same thing. This must not be an issue on Windows either?
- fragmede 4y ago
  You're assuming the ports enumerate the same when the system wakes back up.
  - IshKebab 4y ago
    No he isn't. He's assuming the wires are plugged into the same physical ports and the USB/Thunderbolt system makes that information available (it does).
    - fragmede 4y ago
      No, I’m saying that the same physical ports, on broken hardware, won’t always enumerate to the same physical port. Say port 0 is the one on the left and port 1 is on the right. You’d expect that the computer is able to reliably get that right and be consistent. I’m saying that in the case of broken hardware / bad firmware that it’s not, and port 0 will come up as the right port, with port 1 on the left, with no working, proper way to identify between the two.
jbverschoor 4y ago
My 4K LG monitor stutters and lags my M1 using the usb/DisplayPort cable while having audio enabled (stock cable) Easy fix is to set it to DP1.2 instead of 1.4
- alin23 4y ago
  Well that's a really odd bug :) I'll keep it in my notes for when the next user complains about Lunar making his monitor lag and stutter
  - jbverschoor 4y ago
    I think it's similar to the issues some people see with wifi not working. Because of the datarate which at that point matches the 2.4ghz 5ghz band.
traceroute66 4y ago
One thing I learnt recently is that Windows 10 or below is incapable of remembering window positions. You need to buy third-party software. Microsoft finally fixed this with Windows 11. I'm not making this up, its well documented on many internet forums, including Microsoft's own. Incidentally, made me happy to be a Mac user. Since Apple never had that problem. Infact OS X is magical in how it deals seamlessly with unplugging/plugging external monitors (and no, I don't use an Apple external monitor).
- quercusa 4y ago
  It's not so simple. I've had two (different type) Dell 27" monitors on Win10 for years and never had a problem with losing window positions, until I accepted an 'upgraded' Nvidia driver (27.x to 30.x) a few weeks ago. I rolled back the driver version and it's all good again.
- djitz 4y ago
  Funny, this is actually a common issue with M1s and people are resorting to using third party software
lifeisstillgood 4y ago
>>> That will sometimes, not always, but deterministically when it's most annoying, Oh yes. totally true :-)
thewebcount 4y ago
I have a lot of respect for this developer’s patience. Back when I was a solo developer, these types of issues were death by a thousand paper cuts. I didn’t have the skills to deal with the amount of support and debugging these kinds of problems entail. And it’s especially frustrating when the answer ends up being “It’s due to how the manufacturer of this monitor just didn’t properly implement the spec and there’s nothing I can do to fix it.” I can’t imagine writing software where this is the norm! So kudos to the developer!
- alin23 4y ago
  Thank you! It is indeed a very frustrating kind of work. But still, a lot less frustrating than waking up at 6 AM for a Zoom call with an overseas company I’d be working. I prefer angry users of my own app over demanding (and often not knowing what exactly they demand) bosses.
  - semireg 4y ago
    I work on my own indie label printer app. Let me just tell ya, “label printers…” Sigh. I feel the pain. Stay strong.
    - robk 4y ago
      Just found your software. Looks neat! Buying a copy now for my zebra as soon as I'm on a desktop. Would have bought from mobile if you offered that!
      - semireg 4y ago
        I purposely add friction via “in-app purchase” so users embrace the free trial. Less support issues when you help someone pre-purchase. Very low refund rate / at the expense of revenue. However, you can purchase a license via mobile at my store that sells a label printer: https://mydpi.com https://mydpi.com
    - kayodelycaon 4y ago
avian 4y ago
Maybe someone here can explain the following weird effect: My previous laptop (an HP EliteBook, the exact model escapes me at the moment) had an issue with Linux drivers where it would sometimes crash. When it crashed, the laptop's screen would quickly flash bright-dark-bright-dark... To my eye it looked like one garbage frame with mostly bright pixels and one frame with mostly dark pixels. Nothing weird so far - just a driver bug right? The weird thing was that when I rebooted the laptop after such a crash, the screen brightness would still slightly, but visibly blink in the same pattern, while the monitor was showing normal boot screen and later the login and desktop. The flashing would get less and less noticeable and kind of ring out by itself after a few minutes. After that the monitor was just working as normal. I can't think of a good reason why the monitor would keep blinking like that after a reboot. The best explanation I had was that perhaps some kind of adaptive algorithm for image postprocessing in the LCD driver had rolled off into an extreme and needed a while to get back to normal parameters. But it seems unlikely anything like that would have time constants in the range of minutes. The other possibility I thought about was that the blinking after a reboot was just a illusion created by my eyes, but I found that unlikely. I never saw anything similar.
- alin23 4y ago
  Author here. My intuition says that's probably a faulty backlight panel. Not sure if you know that, but the liquid crystal that creates the image and colors is very dark by itself, so behind the crystal panel there's another panel filled with bright white LEDs to project the image into your eyes. Those LEDs can draw a lot of power and get hot, so they need proper passive cooling. In laptops that's usually achieved by gluing the LEDs to the lid and making the whole lid a massive heatsink (if it's a metal lid). It's possible that your backlight panel was overheating for some reason, or maybe it was just drawing more power than the source (old battery?) could provide. That would explain the continous blinking/ringing until the power/temperature stabilized, but it's really just a guess. It doesn't really sound like a software error anyway.
  - staindk 4y ago
    I hoped to see a more solid answer because I caused a (I think) similar thing to happen on a friend's MacBook a couple years ago. I think I was using some utility to force the resolution down from retina levels for some emulated game we wanted to play. Something went wrong and the top ~1/5 of the screen started flickering insanely quickly. We restarted the laptop and the flickering continued. Then I think we turned it off, left it off for a while, then turned it back on. Still flickering. In the end we left the laptop on for a couple hours and it slowly became less flickery until it was eventually entirely back to normal. Super weird. I was so confused and my friend was so nice about it all that I didn't even think to take a video or document any exact stuff we tried aha.
echeese 4y ago
The URL of this page made me realize Firefox is happy to display spaces in URLs where Chrome will not.
- kiwijamo 4y ago
  Does Firefox not replace spaces with %20? It does for me.
  - Vecr 4y ago
    It matters what your security settings for URL display are. There are attacks related to the URL bar (of course), so you can set Firefox to only display the raw urlencoded URL, or display emojis/non-ASCII characters visually. I guess there is theoretically ideograph attack mitigations in the second mode, but I don't trust it enough for the small benefit as an English language user.
sinoue 4y ago
I was really hoping you were an entomologist and that you had a bug collection of insects attracted to monitors & TVs!
deleted 4y ago
[deleted]
tenebrisalietum 4y ago
> There's nothing you can do to fix it You can buy adapters that forward their own EDID instead of the monitors, I think.
- alin23 4y ago
  Yes, man-in-the-middle for EDID was one of the solutions I thought about. But that can be a security issue [0] and I didn't want to endorse something I don't trust fully. [0] https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_firewall/README.md https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_fi...
backspace_ 4y ago
The title should reflect these are mac issues and solutions
- alin23 4y ago
  It's a free form blog post, not a tutorial.
  - backspace_ 4y ago
    The point being, the topic is all mac related.
seri4l 4y ago
Something I learned not long ago on this site: low quality/too long HDMI cables can make some monitors go black when the user stands or sits on a certain kind of office chair. [1] [2] Apparently it's a known issue at Dell: [3] >Surprisingly, we have also seen this issue connected to gas lift office chairs. When people stand or sit on gas lift chairs, they can generate an EMI spike which is picked up on the video cables, causing a loss of sync. If you have users complaining about displays randomly flickering it could actually be connected to people sitting on gas lift chairs. Again swapping video cables, especially for ones with magnetic ferrite ring on the cable, can eliminate this problem. There is even a white paper about this issue. [1] https://www.youtube.com/watch?v=voW5kEI7JKE https://www.youtube.com/watch?v=voW5kEI7JKE [2] https://www.youtube.com/watch?v=D6pY4t0k1hk https://www.youtube.com/watch?v=D6pY4t0k1hk [3] https://support.displaylink.com/knowledgebase/articles/738618-display-intermittently-blanking-flickering-or-los https://support.displaylink.com/knowledgebase/articles/73861...
- AriedK 4y ago
  This is an issue at our office. We have some cheaper LG monitors that flicker when someone stands up from his gas spring chair. The Dell monitors we have don’t suffer this issue. A paper on the issue: https://www.emcesd.com/pdf/uesd99-w.pdf https://www.emcesd.com/pdf/uesd99-w.pdf Apparently a dangling bag of coins can cause similar issues, but haven’t encountered that so far.
  - exmadscientist 4y ago
    > Apparently a dangling bag of coins can cause similar issues A dangling bag of coins is a famous cheap EMC test for products. All of this sounds like monitor vendors cheaped out on their EMC and need to have their ESD and Immunity certifications reevaluated.... Or maybe it's just the fact that they were dumb enough to ship an I²C interface over a cable as part of the industry spec. Never ship I²C off-board or this kind of crap happens.
    - jacquesm 4y ago
      My own favorite trick was to put a 1st gen cellphone near the device and call it, or to fire a piezo based gas lighter with the shroud removed against device ground. This was for devices that stood a very good chance of being deployed in a hostile environment so being able to withstand that kind of interference wasn't a luxury.
vxNsr 4y ago
As someone who is using display-switch[0] to imitate a hardware KVM switch in software I can say I’ve seen many of these issues in trying to debug the random issues that using ddc creates. Ddc is to http what your county clerk’s website is to (current) healthcare.gov essentially. There’s no standardization at all, it’s maintained by 1000 different people who don’t communicate and don’t care how anyone else is doing it because only like 1/10000 people have heard of it and 1/100000 uses it. [0] https://github.com/haimgel/display-switch https://github.com/haimgel/display-switch
mhasbini 4y ago
A bit off topic: I'm facing an issue where a monitor works only when getting power (220v 60hz) from an outlet but not from an external power generator: ecoflow river pro (220v 60hz) as well. It's the only appliance that doesn't work. It turns on normally but stays black (I use it in mirror mode). Every hour or so it may show the correct content for a glance then it'll turn black. I suspect the power supply source is not the real reason, maybe there's something causing interference with the cable? I'm waiting to have a free weekend to check it out. Edit: I'll check if it's related to this issue: https://news.ycombinator.com/item?id=32631017 https://news.ycombinator.com/item?id=32631017
- alin23 4y ago
  It sounds very likely that this might be electromagnetic interference. The good part is that it’s easy to troubleshoot, just move the generator (or the monitor, whichever is lighter) far away, like in another room or outside. You can also try a different, thicker cable, if you have one handy. The thicker cables are usually better shielded by having a sheath of tiny wires to catch that interference and conduct it to ground.
  - mhasbini 4y ago
    I just tested moving the ecoflow to another room (both door closed ~5m between the ecloflow and the monitor) and used an extension cable to power the monitor. The issue is still happening. Unfortunately I don't have a different HDMI cable at hand now. I'll test another cable as soon as I get my hands on one.
    - mhasbini 4y ago
      I tested another HDMI cable and it's been running smoothly so far.
- alar44 4y ago
  My guess would be the power supply is putting out something closer to a square wave than a sine wave and the monitor power supply is unable to turn that into DC.
cesarb 4y ago
About device serial numbers, see also: https://devblogs.microsoft.com/oldnewthing/20041110-00/?p=37343 https://devblogs.microsoft.com/oldnewthing/20041110-00/?p=37... "Why does Windows not recognize my USB device as the same device if I plug it into a different port?" (2004)
- alin23 4y ago
  Yes, looks like the same thing but applied to USB peripherals instead of DDC-capable ones. I guess changing the serial number and recompiling the firmware for every device is too hard or too slow for some reason.
AshamedCaptain 4y ago
A bit of warning if you try to get a firmware update from Dell to your monitor. Dell's official stance is "we don't sell monitors outside our official channel". If you bought a Dell monitor from Amazon, Dell may NOT accept it for a firmware upgrade.
nickjj 4y ago
A few years ago I had a 10+ year old LCD start to show pink horizontal lines and it partially blended and distorted 30% of the monitor on the left side. The interesting part was you could see a decent amount of the original screen's contents even if you had a different screen being shown such as being behind a lock screen. So imagine a scenario where you had your monitor on with something sensitive open, you turn on your lock screen and go AFK. You could come back 15 minutes later and still see a third of whatever apps you had open at like 50% opacity and it blended through with the pink lines and login screen. It was like an acute burn-in effect. I don't have a picture of it but it was very similar to this effect (I found this when Googling): https://linustechtips.com/uploads/monthly_2017_04/IMG_20170412_082754.thumb.jpg.87e98717fd4e31a02bf4e9eb59a87af7.jpg https://linustechtips.com/uploads/monthly_2017_04/IMG_201704...
- alin23 4y ago
  Sounds very similar to my own issue, described here: https://news.ycombinator.com/item?id=32630077 https://news.ycombinator.com/item?id=32630077
  - nickjj 4y ago
    Oh nice. Yeah it sounds very similar. I never did a touch test to see if it was hotter but heat makes sense. The pink lines and distortions were always present once the problem started but eventually the previous image would fade away. I remember trying everything with no change (different computer, drivers, cables, adapter types, etc.) and also chalked it up to a hardware problem.
throwoutway 4y ago
> After standby or restart, the monitors get swapped by the OS, so moving the cursor to the left monitor will actually appear on the right monitor, and vice-versa. This happens to me all the time, and it's a small; annoyance that's slowly crept up to a frustration now. It also happens that one screen entirely won't 'receive signal' after sleep until I turn unplug/replug the lightning cable
- david_arcos 4y ago
  Same here! Didn't happen with the same monitors when using linux laptops, it's happening only with a Mac
deleted 4y ago
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ajb 4y ago
Fun fact: in some monitors, the EDID flash is writable via the HDMI cable (because the manufacturer forgot to wire the write disable pin to disable this). I know this, because my employer at the time shipped one like that (facepalm). That means that your laptop can corrupt the EDID. Windows and MacOS actually ship with a database of 'corrected EDIDs', in which they look up the EDID of your monitor and use instead the one in the DB, because they know the original is broken. TBF, I think this information is provided by the manufacturer. If you don't need DDC for anything else, the monitor-swapping issue could be fixed by wiring a 4kb I2C flash chip to the DDC pins of the hdmi cable (in place of the monitor, and writing it with a copy of the EDID, with the serial number incremented. A lot of work though. Maybe there is a place for someone to make an HDMI cable with a small embedded microcontroller, for fixing this and other DDC issues.
- dbttdft 4y ago
  Interesting, this was a thing in the VGA days. I didn't know it stills is.
- pabs3 4y ago
  Apparently there are ways to repair EDIDs with only the GPU, no additional electronics required: https://wiki.debian.org/RepairEDID https://wiki.debian.org/RepairEDID
  - ajb 4y ago
    Yeah that can work, but only if the monitor manufacturer forgot to set the EDID flash chip read-only
_hudj 4y ago
To be fair...under the same conditions windows and even Linux a la Nvidia gracefully handles monitor assignment for matching serials so I think it's a bit disingenuous to say this is all on the monitor manufacturer...though I agree ultimately they are the primary party at fault. Source: have this exact scenario and on windows/Linux Nvidia drivers it works and on Mac it flips everytime I come back from sleep. Same brand batch and serial, cables, ports, etc. And I have an m1 pro with a simple HDMI to usbc and an HDMI direct so no hub/bus assignment funny stuff either it's directly plugged into dedicated ports.
- Naomarik 4y ago
  Was skimming through comments sure that someone would confirm this exact thing. In addition to this I have a USB-C hub that includes 2 HDMI inputs, my M1 Max Mac Pro doesn't recognize two monitors connected to it but my Windows laptop does.
deleted 4y ago
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rabbitofdeath 4y ago
Disappointed that this isn't about CRTs and moths and other bugs /s
eek2121 4y ago
IMO the various standards bodies should require validation against all commands and against a number of certified cables. Shoot, an automated test suite could absolutely identify all these issues. You should not be able to display HDMI, DisplayPort, or HDR validation unless your monitor passes these tests. I give them a pass when it is an OS specific bug, but most of the time it is not. My G9, for instance, doesn't sleep AT ALL even though Windows puts the monitor to sleep. Same story with Linux. Samsung just flat out borked sleep mode. FWIW I have an EVGA 3090 on the other end. I have a Samsung G9 and it has many of these bugs...and I haven't even tried macOS on it.
joeblubaugh 4y ago
Maybe users wouldn’t send this in for a brightness control app but: Do you ever get bugs where sometimes after waking from sleep the macOS only offers a few limited resolutions? I have one cheap display and with one of my MacBooks there’s a 25% chance it switches to 1080p after sleep.
- alin23 4y ago
  I did get this bug reported thinking it was caused by Lunar. In the end it turned out to be either a too long cable, or simply a cable that didn’t support the full bandwidth needed when the heat over the wires was increasing resistance. Try a shorter and maybe more expensive cable.
jrockway 4y ago
Kind of annoying that monitors are identified by UUID and not by the physical port they're connected to. Some layer of the system probably has that information, but some other layer probably deletes it. (Even more annoying is when the information isn't deleted, but it's ignored. The Nvidia control panel knows which port each monitor is connected to, and could store the monitor arrangement by port number. Also appreciated would be some way of saying "this monitor is going away for just a second, just keep sending a signal even though you know I can't see it". I have a monitor that likes to hard crash every so often and has to be unplugged, this results in seconds of software freaking out when I'd rather not tell the OS or the apps about the loss of a screen and a switch of "primary display" to some other monitor. Usually a reboot is necessary to get everything's state correct again. Silly.)
- grishka 4y ago
  But then it would get annoying if you have a laptop with multiple identical ports. You'd have to remember which port you need to plug each monitor into.
  - yarg 4y ago
    Keys don't need to be defined by a single component - use the monitor reported value, and failover to something like (reported_value ^ connected_port) if there's a collision.
  - taneq 4y ago
    Exactly. USB devices do this (seem to identify the device by (port, uuid?)) and it's highly annoying having to rearrange everything so the USB-to-serial adapter can reach the correct USB port so I can keep calling it COM5 and not have to switch everything over to COM1 or COM13 or whatever. It also causes weirdness like "my scrollwheel scrolls in one direction when plugged into my laptop and the other direction if I plug it into the USB hub in my keyboard."
    - grishka 4y ago
      *on Windows. On macOS USB serial devices use their serial (lol) numbers or models or whatever for /dev/usbserialXXX, definitely regardless of which port you plug it in.
nfriedly 4y ago
Oh man. I used to have an Asus monitor that would crash if you connected a sleeping MacBook, then woke up the MacBook. You had to unplug the monitors power for a few seconds to reboot it. My current LG 34BK95U had an issue where MacOS would sometimes refuse to send the correct resolution or even aspect ratio. The workaround was to force it to DP1.2 instead of 1.4 (over thunderbolt), but then my Windows machine couldn't send the full resolution/refresh rate over DisplayPort. LG eventually put out a firmware update to fix that. On the other hand, they still haven't fixed the false claim on their website that it supports a 75hz refresh rate. It's identical hardware to their 34WK95U, including the 60hz maximum refresh rate. A previous LG monitor I had falsely claimed 60 USB PD laptop charging on their website. The hardware only supported 7.5w. It was the same scenario, where the consumer model has correct specs, and the business model has identical hardware and falsely inflated specs. I think every single 4k/5k monitor I've ever owned, from LG, Dell, etc. have had useless HDMI ports that were unable to drive the monitor at the correct resolution and refresh rate. You had to settle for either 30hz or a blurry low-rez picture.
quickthrower2 4y ago
Why doesn’t the OS also include the port used in the unique identifier for the monitor?
voltagex_ 4y ago
No one lists DDC support in reviews. On my Acer XB271HU, using SoftMCCS either doesn't work, or causes the monitor to go into factory test mode (flashes full screen R, G, B instead of sleeping). In factory test mode, different commands work or don't work.
mastazi 4y ago
Like most people here on HN, I have experienced all 3 major OSes (Win, Mac and various Linux distros/DEs). One of the points where MacOS struggles when compared to other OSes is, in my opinion, multi monitor support. I'm not sure why, but it seems to me that Apple decided that multi-monitor was not a very important use case and it got de-prioritised (maybe they wanted to push users towards one single, large monitor?), as a result the multi-monitor experience on Mac is not on par with other desktop environments. I'm not saying that the bugs in the post could not happen on other desktop environments, or that other desktop environments don't have bugs of their own, but in general it seems to me that on several Linux DEs and on Windows, I can get a smoother multi-monitor experience than on MacOS.
- spockz 4y ago
  I’m a full time macOS user with multiple screens and haven’t used multiple screens on Linux and Windows in ~15 years. But what is missing from macOS? There was a time when I had displays that got switched around but that was fixed. I can set individual display resolutions, scaling, rotation, colour profile, and relative positions. What more do windows and Linux (kde/gnome) have?
  - mastazi 4y ago
    it would require some time to properly describe the various issues but they are mostly related to 2 thematic areas: window management/snapping in place when in multiple screens and using specific features (e.g. dock, full screen apps) in a multi screen environment. And more in general it's just the presence of little bugs here and there that makes the experience not particularly smooth, for example there are some gestures that you can do when your screens are positioned side by side, but not when your screens are positioned on top of another
pabs3 4y ago
On the monitor swapping situation, it might be possible to modify the EDID on one of the monitors to fix the issue permanently. https://wiki.debian.org/RepairEDID https://wiki.debian.org/RepairEDID
pabs3 4y ago
I wonder if anyone has worked on open source firmware for monitors, so that we can fix some of these bugs. I also wonder how many security vulnerabilities are in DDC parsing firmware. MonitorDarkly proved that there are definitely some: https://github.com/redballoonshenanigans/monitordarkly https://github.com/redballoonshenanigans/monitordarkly
elromulous 4y ago
This post should be renamed "Weird MacOS monitor bugs..."
nuker 4y ago
> on reconnection, the monitors will look identical from the OS side, … And there’s nothing you can do to fix it. Wrong. You still have them connected to different ports, buses, hubs, docks. Hardware path is what tells them apart.
fullstackchris 4y ago
Here's one for you: whenever I have my second monitor plugged in, I'm muted on any video platform (Google Meet, Zoom, etc)
- nielsole 4y ago
  Your second monitor has a microphone jack (without anything connected) which it autoselects for audio input? I think the usual logic is to use the most recently added microphone
deleted 4y ago
[deleted]
iforgotpassword 4y ago
There are a bunch of Fujitsu screens out there from maybe 6+ years ago that have another peculiar bug: the osd breaks after a few years. It manifests in such a way that the language select (that you usually only see the very first time you turn on the screen) flashes for a split-second and then... Nothing. You cannot change any setting of the screen. Not even brightness. The workaround is to issue a factory reset via DDC. Then you can properly select the language again and everything works..... Until the first time the screen goes to standby or gets turned off. Rinse and repeat. It's better than nothing I guess. You can easily find these models on ebay et al, usually people state that "the menu button is broken" or similar.
RektBoy 4y ago
People with mac, pay money for app which controls brightness of their screens? Best joke I've ever heard, thx
- alin23 4y ago
  Looks like you’re out of the loop on this. No OS has the ability to control the real brightness of the monitor out of the box. At best it could dim the brightness through a software overlay, but neither Windows nor Linux implement DDC/CI brightness control by default. You have to use a third party app like: - TwinkleTray [0] on Windows - Lunar [1] on macOS (or MonitorControl [2] if you want a free, but less automated solution) - ddcutil [3] on Linux [0] https://twinkletray.com https://twinkletray.com [1] https://lunar.fyi/ https://lunar.fyi/ [2] https://monitorcontrol.app/ https://monitorcontrol.app/ [3] https://www.ddcutil.com https://www.ddcutil.com EDIT: sorry for answering, I should have taken a look at your comment history before to see that BS comments like this are your thing
  - ayewo 4y ago
    No need to apologize in your edit. In fact, I learnt a few things from your very measured reply. Just move along as you can't please everyone.
  - dinom 4y ago
    I feel obligated to point out that the comment you replied to never said anything about brightness control being built into any OS. They only found it humorous that someone would pay extra for it (presumably because it's free). Then... you went ahead and supported their argument by pointing out that it is indeed free; while also chastising them. I guess my point is that your reply didn't really contribute anything to the conversation other than hurling an insult at the commenter for their past comments. Maybe they really just wanted to make a joke? On some level it would be silly to pay for something that's free, right? Given that you're the original author, could it be that you may have replied as a defense mechanism? At least to some degree? If so, is that proper? Honestly, I don't have a "dog in this fight". I just thought it was an interesting situation.
gernb 4y ago
I should probably just google this but how do I see the UUID numbers for the monitors? I have that swapping problem at work. If it's as simple as swapping one of my monitors with a co-worker that would be great. But rather than just swapping and praying it would be great to be able to verify the UUIDs, before I swap. One to make sure I get a monitor with a different UUID and another to make sure I'm not giving a matching UUID to whoever I swap with
- alin23 4y ago
  On Apple Silicon Macs you can see the computed EDID UUID through the I/O registry: ioreg -r -c AppleCLCD2 | egrep 'ProductAttributes|EDID UUID' I couldn’t see the EDID UUID on Intel Macs, but you could at least dump the EDID on those and see if the bytes are identical. The Lunar CLI (https://lunar.fyi/#cli https://lunar.fyi/#cli) has a way of dumping that: lunar displays --edid If you’re using Linux, you can take a look at ddcutil for dumping the EDID, and on Windows you have NirSoft’s DumpEDID.
  - gernb 4y ago
    Interestingly ioreg reports the same UUID for both monitors but Apple Menu->About Mac->System Report->Graphics/Displays on Intel Mac shows different serial numbers (not UUID) for both monitors. So,.... this sounmds like a bug in MacOS, not the monitors. Whatever they are using for UUID they should be taking into account the serial numbers reported by System Report. Strange though, the M1 Mac shows no serial numbers. Both Macs have the swap problem. Maybe you should add an update to your article. This is clearly an Apple bug, not a monitor manufacture bug. At least in my case. -- update --- Here is the output from ioreg on an M1 Max Mac ioreg -r -c AppleCLCD2 | egrep 'ProductAttributes|EDID UUID' | "DisplayAttributes" = {"SupportsSuspend"=No,"MaximumRefreshRate"=60,"SupportsActiveOff"=No,"PortID"=16,"ProductAttributes"={"ManufacturerID"="HPN","YearOfManufacture"=2021,"SerialNumber"=0,"ProductName"="HP E27u G4","AlphanumericSerialNumber"="CN41201PZ4","LegacyManufacturerID"=8718,"ProductID"=14060,"WeekOfManufacture"=20},"MaxVerticalImageSize"=34,"MaxHorizontalImageSize"=60,"HasHDMILegacyEDID"=No,"Chromaticity"={"Red"={"X"=42816,"Y"=21824},"Green"={"X"=19200,"Y"=41216},"Blue"={"X"=9728,"Y"=4160}},"DefaultColorSpaceIsSRGB"=No,"NativeFormatHorizontalPixels"=2560,"DefaultWhitePoint"={"X"=20544,"Y"=21568,"Gamma"=144179},"SupportsVariableRefreshRate"=No,"AspectRatio"=15,"MinimumRefreshRate"=50,"WhitePoints"=({"X"=20544,"Y"=21568,"Gamma"=144179}),"PreciseAspectRatio"=115652,"ContinuousFrequencySupport"="None","SupportsStandby"=Yes,"NativeFormatVerticalPixels"=1440} | "EDID UUID" = "220EEC36-0000-0000-141F-0104A53C2278" | "DisplayAttributes" = {"SupportsSuspend"=No,"MaximumRefreshRate"=60,"SupportsActiveOff"=No,"PortID"=0,"ProductAttributes"={"ManufacturerID"="HPN","YearOfManufacture"=2021,"SerialNumber"=0,"ProductName"="HP E27u G4","AlphanumericSerialNumber"="CN41201PZN","LegacyManufacturerID"=8718,"ProductID"=14060,"WeekOfManufacture"=20},"MaxVerticalImageSize"=34,"MaxHorizontalImageSize"=60,"HasHDMILegacyEDID"=No,"Chromaticity"={"Red"={"X"=42816,"Y"=21824},"Green"={"X"=19200,"Y"=41216},"Blue"={"X"=9728,"Y"=4160}},"DefaultColorSpaceIsSRGB"=No,"NativeFormatHorizontalPixels"=2560,"DefaultWhitePoint"={"X"=20544,"Y"=21568,"Gamma"=144179},"SupportsVariableRefreshRate"=No,"AspectRatio"=15,"MinimumRefreshRate"=50,"WhitePoints"=({"X"=20544,"Y"=21568,"Gamma"=144179}),"PreciseAspectRatio"=115652,"ContinuousFrequencySupport"="None","SupportsStandby"=Yes,"NativeFormatVerticalPixels"=1440} | "EDID UUID" = "220EEC36-0000-0000-141F-0104A53C2278" Even though the UUIDs are the same you can clearly see the "AlphanumericSerialNumber"s are not "AlphanumericSerialNumber"="CN41201PZ4" "AlphanumericSerialNumber"="CN41201PZN" So this seems clearly a bug with how ever the UUID is created. The Mac has enough into to distinguish the 2 monitors
egorfine 4y ago
My Dell 27" (2015) monitor takes about 10 to 15 seconds to wake up after powersave mode which it turns on in about 1 second after I lock my MacBook. Annoying as hell. Maybe someone could suggest me a fix?

524 points by alin23 4y ago

that install script is not correct. $BIN is never set to anything so it would thankfully crash at the mkdir -p instead of installing to the root directory but either way it wouldn't work

alin23 4y ago
Correct, thanks for catching that! I updated the post.

peanut_worm 4y ago

I had a monitor once with a built in speaker that would pick up random radio broadcasts. I don’t even understand how it happened.

lacoleman 4y ago

Wow... I started at my current job about a year ago and we use Mac Minis as the main workstation for the users. Well as the users started doing more work we got them dual monitors and that is when I started noticing the first problem described. Everyday the same few people would come to me saying that their display settings would swap the main monitor, and sometimes it happened when they went to lunch. I searched online and couldn't really find a sure-fire resolution. I did however, find that if I logged into the administrator account and swapped the monitors, then went into the Energy Saver settings and prevented the Mac from automatically sleeping when the display is off then it keeps the problem away long enough. I will usually have to repeat that process upon an update but I am just glad I found out why this was actually happening.

rjmunro 4y ago

It would be good if the article mentioned the models of buggy monitors, in particular those that don't present unique UUIDs, so that we know which ones to avoid buying. I'm about to choose a new monitor, they all seem much the same, but being reliable against this sort of problem would be a deal-winner for me.

alin23 4y ago
Author here. All vendors do this, it's not only on specific models. The only way to surely avoid this is to buy different types of monitors.

tinus_hn 4y ago

For an example of monitor firmware quality: https://news.ycombinator.com/item?id=32634467 https://news.ycombinator.com/item?id=32634467 Hacking your (Dell 2410u) monitor through ddc

bombcar 4y ago

So many monitors run on similar controllers internally - it would be absolutely wonderful if one or more of those had open source firmware so these bugs could be fixed

rootusrootus 4y ago
Would also be wonderful if they could use a halfway modern CPU so the monitor didn't take 30 seconds to wake up. My CRG9 takes long enough that my macbook will fall asleep again from the password prompt as I'm waiting for the monitor to light up, if I don't keep hitting keys.
- dbttdft 4y ago
  It's a bug with most modern LCDs. Ever since HDMI days they started taking ages to turn on or change modes. I have LCDs from 1997 that turn on and change modes in about 100ms, as opposed to the new 3s-10s. I suspect something extremely stupid, like maybe HDCP crap takes a long time to do its thing (regardless of whether its used) and the process gets blocked on that.
- staindk 4y ago
  That thing looks fancy! Perhaps make sure there isn't a "light sleep" or similar option in its OSD that allows it to blank the screen without fully sleeping. On my monitor (~5ish year old Dell) I have the "Deep Sleep" option disabled and it suits me very well like this.
  - rootusrootus 4y ago
    That's a good catch. There is an 'eco saving' setting that I found after you mentioned it, and it does seem to help the monitor wake up faster. Still not going to win any speed contests, but waking up before the computer goes back to sleep is a win!
- smilespray 4y ago
  I have the same monitor (and a mac), and it sure does take a long time to wake up. I found that disabling all forms of eco saving and deep sleep settings will make the monitor wait for the Mac when waking up. I no longer have to keep hitting keys. It still takes a while to wake up, but at least it's predictable.

swayvil 4y ago

davzie 4y ago
The AI comments are getting out of hand
- samarthr1 4y ago
  How can you tell that it was an AI post though?
  - swayvil 4y ago
    No human would use allcaps italics like that.
    - bredren 4y ago
      Also: “sent it to a tech”
      - oyashirochama 4y ago
        When the AI is cringe.
        deleted 4y ago
        [deleted]
      - swayvil 4y ago
        What's the preferred term? Boffin?
    - robocat 4y ago
      Could you give us a slice-of-life description of your AI life? Preferably without the violent or sexual aspects?
  - 4y ago

BIKESHOPagency 4y ago

This is a kind of look behind the curtain that we rarely get from large software developers. Users are often told by someone down the chain in support it works or doesn't and no explanation why. I find this very fascinating and as a saas developer that makes an app that has to work with external hardware that I often don't have to test on very encouraging. Sometimes, there's no fix and it's not my fault.

alin23 4y ago
I'm also moving towards software that is less dependent on hardware especially because of the headaches that Lunar brought me over the years. You're probably in a much better spot, SaaS is still the best way to make money as a developer, if you don't have to provide too much support.
- alluro2 4y ago
  That "if" does a lot in that sentence :) Just had a typical fun experience: Customer: Your platform doesn't work, when we do this, A happens Me: Hm, we don't have that feature, but I understand your use-case. We could deliver this new feature by tomorrow, but using it that way also inherently means B would happen in such and such cases, so just want to make sure that's what you want? Customer: Let us know when the bug has been fixed, it's urgent and we're losing money because of you (they had 1 month free trial) Me:: It's not a bu...okay, we will Me: * works all night, builds a new feature, fully polished, notifies customer Customer after 2 days: Yet ANOTHER bug with your unstable software!! * describes B
  - alin23 4y ago
    Oh.. that sounds so familiar it almost triggers PTSD-like symptoms inside me. I guess these vocal and demanding people are everywhere, no matter how easy and intuitive the software is. I just had someone ask for a new feature and a discount on my $6 app a few minutes ago. We have to come to terms that this is part of the job where we have such a close connection to the people that use our product.
  - 4y ago

colechristensen 4y ago

I had a very strange monitor bug a few years ago. Dwarf fortress and a weird linux display mode drove my monitor to display a freeze frame of what was going on during the bug at about half opacity with a bit more of a glitchy feel. It stayed after reboot, mode changes, OS changes, retriggers of the bug etc. etc. etc. to the point where it did not make sense at all how the pseudoimage stayed past power cycles and everything else I could imagine. I briefly, and quite seriously, questioned my sanity trying to figure out what was going on. Eventually it just went away. Some firmware bug got an image stuck in memory or something, but man it was weird.

solarengineer 4y ago
I wonder if keeping the display powered off and disconnected from power supply for a minute or more would have helped in your case. I have run into not-so-funny situations due to capacitors. See https://dynamicproxy.livejournal.com/46862.html https://dynamicproxy.livejournal.com/46862.html
- colechristensen 4y ago
  I did everything I could imagine including long periods of disconnecting power and nothing changed, it was very weird.
alin23 4y ago
Author here, it happens right now with my 5 year old LG 27UD88. When the bottom part of the monitor renders something darker (say a Sublime Text window), it also displays a ghost image of a lighter previous image (like the browser window with a white page). It started about a year ago, and every time it happens, the bottom part of the panel is very hot to the touch. After letting a fan blow over that part to cool down the LEDs behind, the problem went away. Which leads me to think this is a hardware problem, and the panel is giving up on me.

avian 4y ago

> Blacking out [...] unplug the power cable, and plug it back again As someone with a monitor that's prone to blacking out like this (not due to Lunar) and was at one point convinced that the monitor got bricked: the key is waiting ~5 minutes before plugging the power back in. A quick unplug-plug in a hurry might not do it. You need to wait for the internal capacitors to discharge to the point where the controller gets properly reset.

alin23 4y ago
Yes, that's a good hint. Most monitor power bricks have very large capacitors, especially when they also charge the laptop through the Thunderbolt connection. That's also the point of the LEDs you see on power bricks. After unplugging, the LED uses up the capacitor current to discharge them faster and also serves as a visual indicator to know when it's safe to plug back the cable.
sroussey 4y ago
Leaving the power off for 5min also has the advantage of cooling the machine.
epakai 4y ago
I have some dells (U2414H) that can get into a really bad state. Sometimes unplugging power is not enough. You have to remove all potential power inputs including display input cables (or shut those devices down too) to get a proper reset.
- tobyhinloopen 4y ago
  Funny, i have the exact same display and I’ve had it randomly not work multiple times. Only unplugging everything seemed to work. Happened maybe 5 times in the many years ive owned it
stanmancan 4y ago
Does pressing power while it’s unplugged expedite the process by attempting to draw power and emptying any capacitors in the process?

colordrops 4y ago

I've got a cablematters thunderbolt hub with two DP outputs connected to two LG monitors. They aren't exactly the same but it doesn't matter, as I'm using Xorg, which doesn't use EDID for layouts. It just uses the output names, which are DP-1, and DP-2, and sometimes the hub flips them. The only way I've found to "fix" this is to use Autorandr, which will update the layout based on the EDID, but the output names remain flipped. This is still an unsolved problem, because i3 uses the output name rather than physical position for where to put workspaces. My other laptop doesn't have an nVidia GPU and runs Sway/Wayland, which doesn't seem to have this issue. If anyone knows how to solve this I'd be eternally grateful. It's been driving me nuts for a year.

pedrocr 4y ago
If you switch from i3 to sway you can use the serial number instead of the port to assign outputs. I think these days it's usable with even the proprietary nVidia driver.
- colordrops 4y ago
  Oh interesting, I understand that sway with Nvidia is developing quickly. I did read maybe less than a month ago though that it's still quite glitchy. Will look into it again.

teetertater 4y ago

Thanks for developing Lunar, I'm a happy user for over a year!

alin23 4y ago
Thank you for the kind message! Happy to hear you find it so useful :)
- guiambros 4y ago
  Another +1 from a happy user! Thank you for developing it. I use several times a day, whenever I'm entering/leaving video calls, or depending if the site/app has dark mode. It's incredibly helpful and reliable!
  - izerik 4y ago
    Every site has dark mode :) https://darkreader.org https://darkreader.org

gonehome 4y ago

Nice overview of interesting bugs. I used to have a ton of issues with my MacBook Pro and thunderbolt monitor. These issues persisted through different MacBooks and monitors (we used the monitors at work and it was a work machine so I had a few). All of these issues finally went away after getting an M1 machine. Maybe a coincidence but fewer monitor connection bugs was one of the noticeable changes for me. Based on the article it might also be because I switched to the apple pro display? Though I can’t remember what happened first. Also off-topic, but this blog has beautiful style and typography.

sroussey 4y ago
I found that after I updated the firmware of the monitors, they worked almost perfectly. And to make them actually work perfectly, I connect them on different sides on the MacBook Pro (intel version still). Took way too long to figure that out.
alin23 4y ago
Thanks, glad you like the styling ^_^ And yes, it's very likely that most of your problems went away because you're using the Pro Display, as it has a much faster CPU than most monitor controllers on the market. Apple displays also support a proprietary USB protocol through which they can communicate with the Mac faster than through the DDC protocol which is still based on two-wire slowpoke I²C. That Apple Native protocol is also supported by Lunar for silky smooth brightness transitions, which is just not possible on DDC, unless the monitor has some kind of built-in fader.

hardcopy 4y ago

I found Lunar very helpful in a South facing apartment with floor to ceiling windows. Without Lunar I had to spend a minute adjusting each monitor, multiple times a day. It solved a problem I never experienced in a home with normal windows.

alin23 4y ago
That's also how Lunar started actually :) I got my first Mac + monitor setup in an apartment with the desk on a closed balcony. It was driving me crazy to press the fiddly LG joystick to get to the brightness menu all day long, so I can follow the ever changing ambient brightness. It's also why Lunar v1.0 only had sunrise/sunset based automatic brightness, not even hotkeys for adjusting the brightness manually.

tristor 4y ago

I wonder if there’s any resources that validate monitor DDC capabilities. It sounds like a lot of the issues are caused by bad monitor firmware

voltagex_ 4y ago
A company called EnTech does this. https://www.entechtaiwan.com/lib/softmccs.shtm https://www.entechtaiwan.com/lib/softmccs.shtm

bluedino 4y ago

Makes me think of the "common knowledge" that Macs don't work properly with external monitors. Fuzzy fonts etc

kmeisthax 4y ago
That's moreso because Apple has a Strongly Held Belief that UIs should never render at fractional scale factors. If it needs to be 150%, it will render a larger virtual desktop at 200% and then downscale. Contrary to Apple, monitor manufacturers have a Strongly Held Belief that monitors should all be one marketable resolution (e.g. 4K) and shape (16:9 widescreen or wider) and users just pick a size. Bigger monitors shouldn't have more pixels in them. The Apple philosophy says that 4K 27" monitors are fundamentally broken hardware that the OS needs to fix at the cost of some display clarity. The manufacturer philosophy says that DisplayPort can't run 5K off a single cable[0] and that nobody wants letterboxing when watching a movie on their new laptop. Apple designs the monitor around what the OS and user need while display manufacturers design around whatever they can buy and repackage. Of course macOS has fuzzy fonts even at 1x, but that's not a display problem. That's a different Strongly Held Belief. Microsoft deliberately bends fonts to fit the pixel grid (they call this ClearType) while Apple uses antialiasing to remain faithful to the glyph shapes as they were originally designed. [0] Or at least this was true as of the release of the iMac 5K almost a decade ago. This is not true anymore but no manufacturer is touching 5K anyway.
- politelemon 4y ago
  This is typical but poor gymnastics which grants benefit of the doubt to brand loyalty. Manufacturers hold no such belief, they are beholden to standards to cater to a wide variety of configurations and setups. Implying it's not made for users is poor form, and simply false.
  - jahewson 4y ago
    If this were true then companies other than Apple would offer monitors that actually do cater to non-broken configurations but they don’t. The parent post does a great job explaining the technical trade-offs and economy of scale optimisations that manufacturers have decided to make, whereas you have only an ad-hominem attack to offer.

mort96 4y ago

The first issue, where multiple monitors have the same vendor/model/manufacture date/serial number, couldn't that be solved by also storing which port it's connected to? That way, if you have two HDMI ports, if both monitors have the same UUID, you store settings based on port rather than UUID. I don't know if this is possible with this new USB-C world, but at least with traditional hardware, it seems like the OS knows which port a monitor is connected to. Anyways, interesting post. It's always fun to discover how much hardware is just broken and doesn't actually correctly implement the protocols or features it's supposed to implement.

erichdongubler 4y ago
This should be at least theoretically possible -- in Windows, for instance, device file paths are based on connection topology, including port address.
feifan 4y ago
Back when I had two monitors, I got the same cables for both and I indiscriminately plugged them into my computer (I had a laptop, so plugging/unplugging happened ~daily). So the mapping between computer port and monitor definitely wasn't going to stay the same.
- mort96 4y ago
  Yeah, it would be a workaround for some cases but not all. It would work in the case of a desktop system where the monitors are always plugged in, and it would work for the case where the monitors go through some kind of USB-C dock (assuming it's possible), but not in your case.
- tonyarkles 4y ago
  Not as convenient but you could label them, if the port was actually factored in.
- Nition 4y ago
  You wouldn't use the "which port was it in last" fallback option unless you already had multiple saved entries where every other bit of data matched.

Karliss 4y ago

The first issue should be possible to deal with at OS level. Even if all the monitors send same serial number, OS should know in which port they are plugged in. Preferably things shouldn't swap if you swapped ports for your two monitors with properly unique serial numbers. But if the serial numbers are identical, ports seem like reasonable fallback since most people with multimonitor setups don't randomly unplug and plug them too often (except laptops).

dt2m 4y ago
Thought the same thing. This must not be an issue on Windows either?
fragmede 4y ago
You're assuming the ports enumerate the same when the system wakes back up.
- IshKebab 4y ago
  No he isn't. He's assuming the wires are plugged into the same physical ports and the USB/Thunderbolt system makes that information available (it does).
  - fragmede 4y ago
    No, I’m saying that the same physical ports, on broken hardware, won’t always enumerate to the same physical port. Say port 0 is the one on the left and port 1 is on the right. You’d expect that the computer is able to reliably get that right and be consistent. I’m saying that in the case of broken hardware / bad firmware that it’s not, and port 0 will come up as the right port, with port 1 on the left, with no working, proper way to identify between the two.

jbverschoor 4y ago

My 4K LG monitor stutters and lags my M1 using the usb/DisplayPort cable while having audio enabled (stock cable) Easy fix is to set it to DP1.2 instead of 1.4

alin23 4y ago
Well that's a really odd bug :) I'll keep it in my notes for when the next user complains about Lunar making his monitor lag and stutter
- jbverschoor 4y ago
  I think it's similar to the issues some people see with wifi not working. Because of the datarate which at that point matches the 2.4ghz 5ghz band.

traceroute66 4y ago

One thing I learnt recently is that Windows 10 or below is incapable of remembering window positions. You need to buy third-party software. Microsoft finally fixed this with Windows 11. I'm not making this up, its well documented on many internet forums, including Microsoft's own. Incidentally, made me happy to be a Mac user. Since Apple never had that problem. Infact OS X is magical in how it deals seamlessly with unplugging/plugging external monitors (and no, I don't use an Apple external monitor).

quercusa 4y ago
It's not so simple. I've had two (different type) Dell 27" monitors on Win10 for years and never had a problem with losing window positions, until I accepted an 'upgraded' Nvidia driver (27.x to 30.x) a few weeks ago. I rolled back the driver version and it's all good again.
djitz 4y ago
Funny, this is actually a common issue with M1s and people are resorting to using third party software

lifeisstillgood 4y ago

>>> That will sometimes, not always, but deterministically when it's most annoying, Oh yes. totally true :-)

thewebcount 4y ago

I have a lot of respect for this developer’s patience. Back when I was a solo developer, these types of issues were death by a thousand paper cuts. I didn’t have the skills to deal with the amount of support and debugging these kinds of problems entail. And it’s especially frustrating when the answer ends up being “It’s due to how the manufacturer of this monitor just didn’t properly implement the spec and there’s nothing I can do to fix it.” I can’t imagine writing software where this is the norm! So kudos to the developer!

alin23 4y ago
Thank you! It is indeed a very frustrating kind of work. But still, a lot less frustrating than waking up at 6 AM for a Zoom call with an overseas company I’d be working. I prefer angry users of my own app over demanding (and often not knowing what exactly they demand) bosses.
- semireg 4y ago
  I work on my own indie label printer app. Let me just tell ya, “label printers…” Sigh. I feel the pain. Stay strong.
  - robk 4y ago
    Just found your software. Looks neat! Buying a copy now for my zebra as soon as I'm on a desktop. Would have bought from mobile if you offered that!
    - semireg 4y ago
      I purposely add friction via “in-app purchase” so users embrace the free trial. Less support issues when you help someone pre-purchase. Very low refund rate / at the expense of revenue. However, you can purchase a license via mobile at my store that sells a label printer: https://mydpi.com https://mydpi.com
  - kayodelycaon 4y ago

avian 4y ago

Maybe someone here can explain the following weird effect: My previous laptop (an HP EliteBook, the exact model escapes me at the moment) had an issue with Linux drivers where it would sometimes crash. When it crashed, the laptop's screen would quickly flash bright-dark-bright-dark... To my eye it looked like one garbage frame with mostly bright pixels and one frame with mostly dark pixels. Nothing weird so far - just a driver bug right? The weird thing was that when I rebooted the laptop after such a crash, the screen brightness would still slightly, but visibly blink in the same pattern, while the monitor was showing normal boot screen and later the login and desktop. The flashing would get less and less noticeable and kind of ring out by itself after a few minutes. After that the monitor was just working as normal. I can't think of a good reason why the monitor would keep blinking like that after a reboot. The best explanation I had was that perhaps some kind of adaptive algorithm for image postprocessing in the LCD driver had rolled off into an extreme and needed a while to get back to normal parameters. But it seems unlikely anything like that would have time constants in the range of minutes. The other possibility I thought about was that the blinking after a reboot was just a illusion created by my eyes, but I found that unlikely. I never saw anything similar.

alin23 4y ago
Author here. My intuition says that's probably a faulty backlight panel. Not sure if you know that, but the liquid crystal that creates the image and colors is very dark by itself, so behind the crystal panel there's another panel filled with bright white LEDs to project the image into your eyes. Those LEDs can draw a lot of power and get hot, so they need proper passive cooling. In laptops that's usually achieved by gluing the LEDs to the lid and making the whole lid a massive heatsink (if it's a metal lid). It's possible that your backlight panel was overheating for some reason, or maybe it was just drawing more power than the source (old battery?) could provide. That would explain the continous blinking/ringing until the power/temperature stabilized, but it's really just a guess. It doesn't really sound like a software error anyway.
- staindk 4y ago
  I hoped to see a more solid answer because I caused a (I think) similar thing to happen on a friend's MacBook a couple years ago. I think I was using some utility to force the resolution down from retina levels for some emulated game we wanted to play. Something went wrong and the top ~1/5 of the screen started flickering insanely quickly. We restarted the laptop and the flickering continued. Then I think we turned it off, left it off for a while, then turned it back on. Still flickering. In the end we left the laptop on for a couple hours and it slowly became less flickery until it was eventually entirely back to normal. Super weird. I was so confused and my friend was so nice about it all that I didn't even think to take a video or document any exact stuff we tried aha.

echeese 4y ago

The URL of this page made me realize Firefox is happy to display spaces in URLs where Chrome will not.

kiwijamo 4y ago
Does Firefox not replace spaces with %20? It does for me.
- Vecr 4y ago
  It matters what your security settings for URL display are. There are attacks related to the URL bar (of course), so you can set Firefox to only display the raw urlencoded URL, or display emojis/non-ASCII characters visually. I guess there is theoretically ideograph attack mitigations in the second mode, but I don't trust it enough for the small benefit as an English language user.

sinoue 4y ago

I was really hoping you were an entomologist and that you had a bug collection of insects attracted to monitors & TVs!

deleted 4y ago

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tenebrisalietum 4y ago

> There's nothing you can do to fix it You can buy adapters that forward their own EDID instead of the monitors, I think.

alin23 4y ago
Yes, man-in-the-middle for EDID was one of the solutions I thought about. But that can be a security issue [0] and I didn't want to endorse something I don't trust fully. [0] https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_firewall/README.md https://git.cuvoodoo.info/kingkevin/board/src/branch/hdmi_fi...

backspace_ 4y ago

The title should reflect these are mac issues and solutions

alin23 4y ago
It's a free form blog post, not a tutorial.
- backspace_ 4y ago
  The point being, the topic is all mac related.

seri4l 4y ago

Something I learned not long ago on this site: low quality/too long HDMI cables can make some monitors go black when the user stands or sits on a certain kind of office chair. [1] [2] Apparently it's a known issue at Dell: [3] >Surprisingly, we have also seen this issue connected to gas lift office chairs. When people stand or sit on gas lift chairs, they can generate an EMI spike which is picked up on the video cables, causing a loss of sync. If you have users complaining about displays randomly flickering it could actually be connected to people sitting on gas lift chairs. Again swapping video cables, especially for ones with magnetic ferrite ring on the cable, can eliminate this problem. There is even a white paper about this issue. [1] https://www.youtube.com/watch?v=voW5kEI7JKE https://www.youtube.com/watch?v=voW5kEI7JKE [2] https://www.youtube.com/watch?v=D6pY4t0k1hk https://www.youtube.com/watch?v=D6pY4t0k1hk [3] https://support.displaylink.com/knowledgebase/articles/738618-display-intermittently-blanking-flickering-or-los https://support.displaylink.com/knowledgebase/articles/73861...

AriedK 4y ago
This is an issue at our office. We have some cheaper LG monitors that flicker when someone stands up from his gas spring chair. The Dell monitors we have don’t suffer this issue. A paper on the issue: https://www.emcesd.com/pdf/uesd99-w.pdf https://www.emcesd.com/pdf/uesd99-w.pdf Apparently a dangling bag of coins can cause similar issues, but haven’t encountered that so far.
- exmadscientist 4y ago
  > Apparently a dangling bag of coins can cause similar issues A dangling bag of coins is a famous cheap EMC test for products. All of this sounds like monitor vendors cheaped out on their EMC and need to have their ESD and Immunity certifications reevaluated.... Or maybe it's just the fact that they were dumb enough to ship an I²C interface over a cable as part of the industry spec. Never ship I²C off-board or this kind of crap happens.
  - jacquesm 4y ago
    My own favorite trick was to put a 1st gen cellphone near the device and call it, or to fire a piezo based gas lighter with the shroud removed against device ground. This was for devices that stood a very good chance of being deployed in a hostile environment so being able to withstand that kind of interference wasn't a luxury.

vxNsr 4y ago

As someone who is using display-switch[0] to imitate a hardware KVM switch in software I can say I’ve seen many of these issues in trying to debug the random issues that using ddc creates. Ddc is to http what your county clerk’s website is to (current) healthcare.gov essentially. There’s no standardization at all, it’s maintained by 1000 different people who don’t communicate and don’t care how anyone else is doing it because only like 1/10000 people have heard of it and 1/100000 uses it. [0] https://github.com/haimgel/display-switch https://github.com/haimgel/display-switch

mhasbini 4y ago

A bit off topic: I'm facing an issue where a monitor works only when getting power (220v 60hz) from an outlet but not from an external power generator: ecoflow river pro (220v 60hz) as well. It's the only appliance that doesn't work. It turns on normally but stays black (I use it in mirror mode). Every hour or so it may show the correct content for a glance then it'll turn black. I suspect the power supply source is not the real reason, maybe there's something causing interference with the cable? I'm waiting to have a free weekend to check it out. Edit: I'll check if it's related to this issue: https://news.ycombinator.com/item?id=32631017 https://news.ycombinator.com/item?id=32631017

alin23 4y ago
It sounds very likely that this might be electromagnetic interference. The good part is that it’s easy to troubleshoot, just move the generator (or the monitor, whichever is lighter) far away, like in another room or outside. You can also try a different, thicker cable, if you have one handy. The thicker cables are usually better shielded by having a sheath of tiny wires to catch that interference and conduct it to ground.
- mhasbini 4y ago
  I just tested moving the ecoflow to another room (both door closed ~5m between the ecloflow and the monitor) and used an extension cable to power the monitor. The issue is still happening. Unfortunately I don't have a different HDMI cable at hand now. I'll test another cable as soon as I get my hands on one.
  - mhasbini 4y ago
    I tested another HDMI cable and it's been running smoothly so far.
alar44 4y ago
My guess would be the power supply is putting out something closer to a square wave than a sine wave and the monitor power supply is unable to turn that into DC.

cesarb 4y ago

About device serial numbers, see also: https://devblogs.microsoft.com/oldnewthing/20041110-00/?p=37343 https://devblogs.microsoft.com/oldnewthing/20041110-00/?p=37... "Why does Windows not recognize my USB device as the same device if I plug it into a different port?" (2004)

alin23 4y ago
Yes, looks like the same thing but applied to USB peripherals instead of DDC-capable ones. I guess changing the serial number and recompiling the firmware for every device is too hard or too slow for some reason.

AshamedCaptain 4y ago

A bit of warning if you try to get a firmware update from Dell to your monitor. Dell's official stance is "we don't sell monitors outside our official channel". If you bought a Dell monitor from Amazon, Dell may NOT accept it for a firmware upgrade.

nickjj 4y ago

A few years ago I had a 10+ year old LCD start to show pink horizontal lines and it partially blended and distorted 30% of the monitor on the left side. The interesting part was you could see a decent amount of the original screen's contents even if you had a different screen being shown such as being behind a lock screen. So imagine a scenario where you had your monitor on with something sensitive open, you turn on your lock screen and go AFK. You could come back 15 minutes later and still see a third of whatever apps you had open at like 50% opacity and it blended through with the pink lines and login screen. It was like an acute burn-in effect. I don't have a picture of it but it was very similar to this effect (I found this when Googling): https://linustechtips.com/uploads/monthly_2017_04/IMG_20170412_082754.thumb.jpg.87e98717fd4e31a02bf4e9eb59a87af7.jpg https://linustechtips.com/uploads/monthly_2017_04/IMG_201704...

alin23 4y ago
Sounds very similar to my own issue, described here: https://news.ycombinator.com/item?id=32630077 https://news.ycombinator.com/item?id=32630077
- nickjj 4y ago
  Oh nice. Yeah it sounds very similar. I never did a touch test to see if it was hotter but heat makes sense. The pink lines and distortions were always present once the problem started but eventually the previous image would fade away. I remember trying everything with no change (different computer, drivers, cables, adapter types, etc.) and also chalked it up to a hardware problem.

throwoutway 4y ago

> After standby or restart, the monitors get swapped by the OS, so moving the cursor to the left monitor will actually appear on the right monitor, and vice-versa. This happens to me all the time, and it's a small; annoyance that's slowly crept up to a frustration now. It also happens that one screen entirely won't 'receive signal' after sleep until I turn unplug/replug the lightning cable

david_arcos 4y ago
Same here! Didn't happen with the same monitors when using linux laptops, it's happening only with a Mac

deleted 4y ago

[deleted]

ajb 4y ago

Fun fact: in some monitors, the EDID flash is writable via the HDMI cable (because the manufacturer forgot to wire the write disable pin to disable this). I know this, because my employer at the time shipped one like that (facepalm). That means that your laptop can corrupt the EDID. Windows and MacOS actually ship with a database of 'corrected EDIDs', in which they look up the EDID of your monitor and use instead the one in the DB, because they know the original is broken. TBF, I think this information is provided by the manufacturer. If you don't need DDC for anything else, the monitor-swapping issue could be fixed by wiring a 4kb I2C flash chip to the DDC pins of the hdmi cable (in place of the monitor, and writing it with a copy of the EDID, with the serial number incremented. A lot of work though. Maybe there is a place for someone to make an HDMI cable with a small embedded microcontroller, for fixing this and other DDC issues.

dbttdft 4y ago
Interesting, this was a thing in the VGA days. I didn't know it stills is.
pabs3 4y ago
Apparently there are ways to repair EDIDs with only the GPU, no additional electronics required: https://wiki.debian.org/RepairEDID https://wiki.debian.org/RepairEDID
- ajb 4y ago
  Yeah that can work, but only if the monitor manufacturer forgot to set the EDID flash chip read-only

_hudj 4y ago

To be fair...under the same conditions windows and even Linux a la Nvidia gracefully handles monitor assignment for matching serials so I think it's a bit disingenuous to say this is all on the monitor manufacturer...though I agree ultimately they are the primary party at fault. Source: have this exact scenario and on windows/Linux Nvidia drivers it works and on Mac it flips everytime I come back from sleep. Same brand batch and serial, cables, ports, etc. And I have an m1 pro with a simple HDMI to usbc and an HDMI direct so no hub/bus assignment funny stuff either it's directly plugged into dedicated ports.

Naomarik 4y ago
Was skimming through comments sure that someone would confirm this exact thing. In addition to this I have a USB-C hub that includes 2 HDMI inputs, my M1 Max Mac Pro doesn't recognize two monitors connected to it but my Windows laptop does.

deleted 4y ago

[deleted]

rabbitofdeath 4y ago

Disappointed that this isn't about CRTs and moths and other bugs /s

eek2121 4y ago

IMO the various standards bodies should require validation against all commands and against a number of certified cables. Shoot, an automated test suite could absolutely identify all these issues. You should not be able to display HDMI, DisplayPort, or HDR validation unless your monitor passes these tests. I give them a pass when it is an OS specific bug, but most of the time it is not. My G9, for instance, doesn't sleep AT ALL even though Windows puts the monitor to sleep. Same story with Linux. Samsung just flat out borked sleep mode. FWIW I have an EVGA 3090 on the other end. I have a Samsung G9 and it has many of these bugs...and I haven't even tried macOS on it.

joeblubaugh 4y ago

Maybe users wouldn’t send this in for a brightness control app but: Do you ever get bugs where sometimes after waking from sleep the macOS only offers a few limited resolutions? I have one cheap display and with one of my MacBooks there’s a 25% chance it switches to 1080p after sleep.

alin23 4y ago
I did get this bug reported thinking it was caused by Lunar. In the end it turned out to be either a too long cable, or simply a cable that didn’t support the full bandwidth needed when the heat over the wires was increasing resistance. Try a shorter and maybe more expensive cable.

jrockway 4y ago

Kind of annoying that monitors are identified by UUID and not by the physical port they're connected to. Some layer of the system probably has that information, but some other layer probably deletes it. (Even more annoying is when the information isn't deleted, but it's ignored. The Nvidia control panel knows which port each monitor is connected to, and could store the monitor arrangement by port number. Also appreciated would be some way of saying "this monitor is going away for just a second, just keep sending a signal even though you know I can't see it". I have a monitor that likes to hard crash every so often and has to be unplugged, this results in seconds of software freaking out when I'd rather not tell the OS or the apps about the loss of a screen and a switch of "primary display" to some other monitor. Usually a reboot is necessary to get everything's state correct again. Silly.)

grishka 4y ago
But then it would get annoying if you have a laptop with multiple identical ports. You'd have to remember which port you need to plug each monitor into.
- yarg 4y ago
  Keys don't need to be defined by a single component - use the monitor reported value, and failover to something like (reported_value ^ connected_port) if there's a collision.
- taneq 4y ago
  Exactly. USB devices do this (seem to identify the device by (port, uuid?)) and it's highly annoying having to rearrange everything so the USB-to-serial adapter can reach the correct USB port so I can keep calling it COM5 and not have to switch everything over to COM1 or COM13 or whatever. It also causes weirdness like "my scrollwheel scrolls in one direction when plugged into my laptop and the other direction if I plug it into the USB hub in my keyboard."
  - grishka 4y ago
    *on Windows. On macOS USB serial devices use their serial (lol) numbers or models or whatever for /dev/usbserialXXX, definitely regardless of which port you plug it in.

nfriedly 4y ago

Oh man. I used to have an Asus monitor that would crash if you connected a sleeping MacBook, then woke up the MacBook. You had to unplug the monitors power for a few seconds to reboot it. My current LG 34BK95U had an issue where MacOS would sometimes refuse to send the correct resolution or even aspect ratio. The workaround was to force it to DP1.2 instead of 1.4 (over thunderbolt), but then my Windows machine couldn't send the full resolution/refresh rate over DisplayPort. LG eventually put out a firmware update to fix that. On the other hand, they still haven't fixed the false claim on their website that it supports a 75hz refresh rate. It's identical hardware to their 34WK95U, including the 60hz maximum refresh rate. A previous LG monitor I had falsely claimed 60 USB PD laptop charging on their website. The hardware only supported 7.5w. It was the same scenario, where the consumer model has correct specs, and the business model has identical hardware and falsely inflated specs. I think every single 4k/5k monitor I've ever owned, from LG, Dell, etc. have had useless HDMI ports that were unable to drive the monitor at the correct resolution and refresh rate. You had to settle for either 30hz or a blurry low-rez picture.

quickthrower2 4y ago

Why doesn’t the OS also include the port used in the unique identifier for the monitor?

voltagex_ 4y ago

No one lists DDC support in reviews. On my Acer XB271HU, using SoftMCCS either doesn't work, or causes the monitor to go into factory test mode (flashes full screen R, G, B instead of sleeping). In factory test mode, different commands work or don't work.

mastazi 4y ago

Like most people here on HN, I have experienced all 3 major OSes (Win, Mac and various Linux distros/DEs). One of the points where MacOS struggles when compared to other OSes is, in my opinion, multi monitor support. I'm not sure why, but it seems to me that Apple decided that multi-monitor was not a very important use case and it got de-prioritised (maybe they wanted to push users towards one single, large monitor?), as a result the multi-monitor experience on Mac is not on par with other desktop environments. I'm not saying that the bugs in the post could not happen on other desktop environments, or that other desktop environments don't have bugs of their own, but in general it seems to me that on several Linux DEs and on Windows, I can get a smoother multi-monitor experience than on MacOS.

spockz 4y ago
I’m a full time macOS user with multiple screens and haven’t used multiple screens on Linux and Windows in ~15 years. But what is missing from macOS? There was a time when I had displays that got switched around but that was fixed. I can set individual display resolutions, scaling, rotation, colour profile, and relative positions. What more do windows and Linux (kde/gnome) have?
- mastazi 4y ago
  it would require some time to properly describe the various issues but they are mostly related to 2 thematic areas: window management/snapping in place when in multiple screens and using specific features (e.g. dock, full screen apps) in a multi screen environment. And more in general it's just the presence of little bugs here and there that makes the experience not particularly smooth, for example there are some gestures that you can do when your screens are positioned side by side, but not when your screens are positioned on top of another

pabs3 4y ago

On the monitor swapping situation, it might be possible to modify the EDID on one of the monitors to fix the issue permanently. https://wiki.debian.org/RepairEDID https://wiki.debian.org/RepairEDID

pabs3 4y ago

I wonder if anyone has worked on open source firmware for monitors, so that we can fix some of these bugs. I also wonder how many security vulnerabilities are in DDC parsing firmware. MonitorDarkly proved that there are definitely some: https://github.com/redballoonshenanigans/monitordarkly https://github.com/redballoonshenanigans/monitordarkly

elromulous 4y ago

This post should be renamed "Weird MacOS monitor bugs..."

nuker 4y ago

> on reconnection, the monitors will look identical from the OS side, … And there’s nothing you can do to fix it. Wrong. You still have them connected to different ports, buses, hubs, docks. Hardware path is what tells them apart.

fullstackchris 4y ago

Here's one for you: whenever I have my second monitor plugged in, I'm muted on any video platform (Google Meet, Zoom, etc)

nielsole 4y ago
Your second monitor has a microphone jack (without anything connected) which it autoselects for audio input? I think the usual logic is to use the most recently added microphone

deleted 4y ago

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iforgotpassword 4y ago

There are a bunch of Fujitsu screens out there from maybe 6+ years ago that have another peculiar bug: the osd breaks after a few years. It manifests in such a way that the language select (that you usually only see the very first time you turn on the screen) flashes for a split-second and then... Nothing. You cannot change any setting of the screen. Not even brightness. The workaround is to issue a factory reset via DDC. Then you can properly select the language again and everything works..... Until the first time the screen goes to standby or gets turned off. Rinse and repeat. It's better than nothing I guess. You can easily find these models on ebay et al, usually people state that "the menu button is broken" or similar.

RektBoy 4y ago

People with mac, pay money for app which controls brightness of their screens? Best joke I've ever heard, thx

alin23 4y ago
Looks like you’re out of the loop on this. No OS has the ability to control the real brightness of the monitor out of the box. At best it could dim the brightness through a software overlay, but neither Windows nor Linux implement DDC/CI brightness control by default. You have to use a third party app like: - TwinkleTray [0] on Windows - Lunar [1] on macOS (or MonitorControl [2] if you want a free, but less automated solution) - ddcutil [3] on Linux [0] https://twinkletray.com https://twinkletray.com [1] https://lunar.fyi/ https://lunar.fyi/ [2] https://monitorcontrol.app/ https://monitorcontrol.app/ [3] https://www.ddcutil.com https://www.ddcutil.com EDIT: sorry for answering, I should have taken a look at your comment history before to see that BS comments like this are your thing
- ayewo 4y ago
  No need to apologize in your edit. In fact, I learnt a few things from your very measured reply. Just move along as you can't please everyone.
- dinom 4y ago
  I feel obligated to point out that the comment you replied to never said anything about brightness control being built into any OS. They only found it humorous that someone would pay extra for it (presumably because it's free). Then... you went ahead and supported their argument by pointing out that it is indeed free; while also chastising them. I guess my point is that your reply didn't really contribute anything to the conversation other than hurling an insult at the commenter for their past comments. Maybe they really just wanted to make a joke? On some level it would be silly to pay for something that's free, right? Given that you're the original author, could it be that you may have replied as a defense mechanism? At least to some degree? If so, is that proper? Honestly, I don't have a "dog in this fight". I just thought it was an interesting situation.

gernb 4y ago

I should probably just google this but how do I see the UUID numbers for the monitors? I have that swapping problem at work. If it's as simple as swapping one of my monitors with a co-worker that would be great. But rather than just swapping and praying it would be great to be able to verify the UUIDs, before I swap. One to make sure I get a monitor with a different UUID and another to make sure I'm not giving a matching UUID to whoever I swap with

alin23 4y ago
On Apple Silicon Macs you can see the computed EDID UUID through the I/O registry: ioreg -r -c AppleCLCD2 | egrep 'ProductAttributes|EDID UUID' I couldn’t see the EDID UUID on Intel Macs, but you could at least dump the EDID on those and see if the bytes are identical. The Lunar CLI (https://lunar.fyi/#cli https://lunar.fyi/#cli) has a way of dumping that: lunar displays --edid If you’re using Linux, you can take a look at ddcutil for dumping the EDID, and on Windows you have NirSoft’s DumpEDID.
- gernb 4y ago
  Interestingly ioreg reports the same UUID for both monitors but Apple Menu->About Mac->System Report->Graphics/Displays on Intel Mac shows different serial numbers (not UUID) for both monitors. So,.... this sounmds like a bug in MacOS, not the monitors. Whatever they are using for UUID they should be taking into account the serial numbers reported by System Report. Strange though, the M1 Mac shows no serial numbers. Both Macs have the swap problem. Maybe you should add an update to your article. This is clearly an Apple bug, not a monitor manufacture bug. At least in my case. -- update --- Here is the output from ioreg on an M1 Max Mac ioreg -r -c AppleCLCD2 | egrep 'ProductAttributes|EDID UUID' | "DisplayAttributes" = {"SupportsSuspend"=No,"MaximumRefreshRate"=60,"SupportsActiveOff"=No,"PortID"=16,"ProductAttributes"={"ManufacturerID"="HPN","YearOfManufacture"=2021,"SerialNumber"=0,"ProductName"="HP E27u G4","AlphanumericSerialNumber"="CN41201PZ4","LegacyManufacturerID"=8718,"ProductID"=14060,"WeekOfManufacture"=20},"MaxVerticalImageSize"=34,"MaxHorizontalImageSize"=60,"HasHDMILegacyEDID"=No,"Chromaticity"={"Red"={"X"=42816,"Y"=21824},"Green"={"X"=19200,"Y"=41216},"Blue"={"X"=9728,"Y"=4160}},"DefaultColorSpaceIsSRGB"=No,"NativeFormatHorizontalPixels"=2560,"DefaultWhitePoint"={"X"=20544,"Y"=21568,"Gamma"=144179},"SupportsVariableRefreshRate"=No,"AspectRatio"=15,"MinimumRefreshRate"=50,"WhitePoints"=({"X"=20544,"Y"=21568,"Gamma"=144179}),"PreciseAspectRatio"=115652,"ContinuousFrequencySupport"="None","SupportsStandby"=Yes,"NativeFormatVerticalPixels"=1440} | "EDID UUID" = "220EEC36-0000-0000-141F-0104A53C2278" | "DisplayAttributes" = {"SupportsSuspend"=No,"MaximumRefreshRate"=60,"SupportsActiveOff"=No,"PortID"=0,"ProductAttributes"={"ManufacturerID"="HPN","YearOfManufacture"=2021,"SerialNumber"=0,"ProductName"="HP E27u G4","AlphanumericSerialNumber"="CN41201PZN","LegacyManufacturerID"=8718,"ProductID"=14060,"WeekOfManufacture"=20},"MaxVerticalImageSize"=34,"MaxHorizontalImageSize"=60,"HasHDMILegacyEDID"=No,"Chromaticity"={"Red"={"X"=42816,"Y"=21824},"Green"={"X"=19200,"Y"=41216},"Blue"={"X"=9728,"Y"=4160}},"DefaultColorSpaceIsSRGB"=No,"NativeFormatHorizontalPixels"=2560,"DefaultWhitePoint"={"X"=20544,"Y"=21568,"Gamma"=144179},"SupportsVariableRefreshRate"=No,"AspectRatio"=15,"MinimumRefreshRate"=50,"WhitePoints"=({"X"=20544,"Y"=21568,"Gamma"=144179}),"PreciseAspectRatio"=115652,"ContinuousFrequencySupport"="None","SupportsStandby"=Yes,"NativeFormatVerticalPixels"=1440} | "EDID UUID" = "220EEC36-0000-0000-141F-0104A53C2278" Even though the UUIDs are the same you can clearly see the "AlphanumericSerialNumber"s are not "AlphanumericSerialNumber"="CN41201PZ4" "AlphanumericSerialNumber"="CN41201PZN" So this seems clearly a bug with how ever the UUID is created. The Mac has enough into to distinguish the 2 monitors

egorfine 4y ago

My Dell 27" (2015) monitor takes about 10 to 15 seconds to wake up after powersave mode which it turns on in about 1 second after I lock my MacBook. Annoying as hell. Maybe someone could suggest me a fix?