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One time an ADC chip in my Rigol scope died. From the pinout, it was clearly a Chinese clone of a TI part. I wanted a replacement clone part, but it wasn't avai
by jjoonathan 3y ago
One time an ADC chip in my Rigol scope died. From the pinout, it was clearly a Chinese clone of a TI part. I wanted a replacement clone part, but it wasn't available under the clone name, so I bought the cheapest most suspicious listing of the TI part that I could find, hoping I would get the clone. Unfortunately I got the genuine article. So it goes. https://goo.gl/photos/dxU3ChWUcvCMDW4N9 https://goo.gl/photos/dxU3ChWUcvCMDW4N9
Fortunately I was able to make do with the genuine part, though not trivially: there was a weird clock termination difference. It's never easy, is it?
- baz00 3y agoThis sort of stuff scares me with modern Chinese test gear. I'd rather have some rancid old HP or Tek stuff from the 90s and keep a couple of parts mules in the cupboard.
- buildbot 3y agoThe lab I worked in during undergrad had a massive pile of old scopes and such. One of them was this monstrosity of a scope from the 80s (?) that had a built in thermal printer to capture the output, and was I think in the 1-2ghz range! I’m sure it’s still there, working, waiting for the next undergrad to need its assistance.
- mips_r4300i 3y agoProbably an old Lecroy! With the floppy drive next to the thermal printer.
- buildbot 3y agoYES! You jogged my memory - it absolutely was a lecroy with a floppy disk as well! What a cool piece of equipment. Though I won’t say I was too sad when we got to use a 5GHz touch screen Tektronix instead! It ran Windows XP and was generally super awesome to use.
- CamperBob2 3y agoThat's some drop-dead awesome troubleshooting work there. Kudos. You are now ready to tackle the boss level: reverse-engineer the Maxim trigger chips on the TDS 694C. :)
- Joker_vD 3y agoYeah, you never want to find yourself in a "would you like the Chinese genuine part or the French knock-off?" kind of situation.
- jacquesm 3y ago> French knock-off Don't joke, they exist.
- preinheimer 3y agoThis has serious William Gibson cyberpunk vibes to me.
- varjag 3y agoPsst kids if you need a factory traceable brick of js28f256 in i-temp, hmu. Ain't getting nerve attenuation syndrome with that. (not even kidding!)
- baybal2 3y ago[dead]
- sitzkrieg 3y agohow about a bin of OTP 4bitters that were apparently all already been had or cooked :-(
- 6LLvveMx2koXfwn 3y agoLeft: a technical diagram of the setup. :clap
- pavel_lishin 3y agoHow do you make Google Photos act as a sort-of-blog post?
- jffry 3y agoWhen editing an album in Google Photos, there's controls at the top right (on desktop browser at least) that let you insert text or maps inbetween photos
- genericone 3y agoHuh, you learn interesting things everyday in unusual places. Look forward to seeing more google-photos blog-posts from this new discovery. /s I hope.
- dkjaudyeqooe 3y agoThat's actually really effective, and refreshingly lightweight. It even lets people comment.
- dkjaudyeqooe 3y agoI can only imagine your review: "Selected totally dodgy looking seller to source fake part disappointed to receive genuine item, one star for being unnecessarily honest"
- a1369209993 3y agoReminds me of the bit in Jekyll and Hyde where it turns out the doctor's alchemical formula only worked in the first place not because of the salt he using, but because of a unknown trace contaminant in the salt. Also, of course: "instead of bobcat, package contained chair".
- jacquesm 3y agoMore than one major scientific discovery was made in that way. Penicillin is probably the best and most well known example.
- taneq 3y ago“The most exciting words in science aren’t “eureka!” but “that’s funny…”” - Asimov
- gunapologist99 3y agoFaraday and magnetism..
- logifail 3y ago> it turns out the doctor's alchemical formula only worked in the first place not because of the salt he using, but because of a unknown trace contaminant in the salt Reminds me of reading about "Fogbank"... https://en.wikipedia.org/wiki/Fogbank https://en.wikipedia.org/wiki/Fogbank: "In March 2007, engineers devised a manufacturing process for Fogbank. Unfortunately, the material turned out to have problems when tested, and in September 2007 the Fogbank project was upgraded to "Code Blue" status by the NNSA, making it a major priority [...] The experience of reverse engineering Fogbank produced some improvements in scientific knowledge of the process. The new production scientists noticed that certain problems in production resembled those noted by the original team. These problems were traced to a particular impurity in the final product that was required to meet quality standards. A root cause investigation showed that input materials were subject to cleaning processes that had not existed during the original production run. This cleaning removed a substance that generated the required impurity. With the implicit role of this substance finally understood, the production scientists can control output quality better than during the original run."
- stavros 3y agoI love the "I didn't want to buy another expensive $930 scope, so I fixed it using plain old elbow grease and $7000 worth of expert hardware designer time". I have also spent thousands of dollars of my time so I wouldn't have to replace a $3 part.
- AussieWog93 3y agoHey, what else would he have been doing with that time? Watching Netflix? Fixing the scope sounds way more fun!
- stavros 3y agoThat is very true, I can't count that time as cost, it was pure enjoyment.
- tialaramex 3y agoAnd we can rely on this as a force in some cases. Some years ago at an IETF one of the talks was about an outfit whose hosting or cloud or something pricing change was designed to prod people towards IPv6. Something like, on contract renewal you could keep the same config, same price, for the next period, but you only get IPv6, or, you could decide you must have IPv4 still, but that's a separate product now, so you need to get your finance people to sign off on the revised billing with the small extra cost for the v4 addresses you'll need as they're no longer baked in. One reason to do this was because v4 addressing does actually cost money, but they also expected it would itself drive migrations to IPv6 and they were correct. Because "We should fix our thing to work with IPv6" sounds potentially like a fun learning experience whereas "We should talk to our finance department" sounds miserable so they're obviously gonna put a few hours into making IPv6 work rather than take the "easy" option. IIRC They did have customers who paid for IPv4 after the changes, but the vast majority went IPv6 only.
- stavros 3y agoThat's actually pretty smart marketing, thanks for that.
- mips_r4300i 3y agoExcellent analysis and fix of the problem! I've found Chinese clones are always subtly different than the parts they supposedly replace.
- creer 3y ago> clearly That was some repair! Bravo! And fantastic write-up - technical diagram included.
- calamari4065 3y agoI honestly don't know if I'd have the stones to replace a scope ADC. But then again if it's already dead you can't kill it more.
- JohnFen 3y ago> But then again if it's already dead you can't kill it more. I live by this, and try my hand at fixing everything that I would otherwise junk. Some of the time, I even succeed!
- ace2358 3y agoThat was a great ‘blog post’! It’s awesome to see such a complicated repair coming down to a single 10ohm resistor. Amazing diagnosis! I have a digital mixer for music recording that is also an audio interface for my computer. I had a somewhat known problem where 12 out of the 16 channels stop working. Turns out what’s going on is the mixer is ‘gating’ the audio signal because the digital gate effect (that is built in) is claiming that it is receiving an input such that it will attenuate the audio signal. I don’t even know how to diagnose a problem like this. It’s awesome watching someone who does!