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I'm a bit surprised there was no mention of semiconductors (mostly capacitors?) going bad on 1990's hard drives. I want to rescue the Fast SCSI2 drive on my old

I'm a bit surprised there was no mention of semiconductors (mostly capacitors?) going bad on 1990's hard drives. I want to rescue the Fast SCSI2 drive on my old Amiga at some point and never thought the problem might be inside. If the electronics on server-quality drives (it sounds like a jet engine) are this reliable, then I'll be thankful for having just one problem and not two.

jimmaswell 2y ago
Hm, I have some classic scsi drives still kicking in some old Macintoshes, maybe I aught to back them up. They're funny, sometimes they get stuck and I have to whack them with the rubber side of a screwdriver to start them up.
Panzer04 2y ago
Do HDDs have many electrolytics? Those are the main culprits for going bad, and are usually used for power electronics, not controllers/processing circuitry (they don't need the bulk capacitance that you'd usually use an electrolytic for)
- dougg3 2y ago
  There are indeed some aluminum electrolytics hiding on Quantum drives. They look sneakily like tantalum caps, but they're just cans hiding inside a plastic cover. Here's one where I accidentally broke the cover, revealing what's underneath: https://i.imgur.com/LdjUx3v.jpeg https://i.imgur.com/LdjUx3v.jpeg
  - ComputerGuru 2y ago
    You can’t convince me that’s not intentionally disguised like that.
    - yborg 2y ago
      It's more likely so these could be used with a pick and place machine. They're obviously lytics if you look at the ends. I don't know why everything has to be a conspiracy these days.
    - mystified5016 2y ago
      No reasonable EE would mistake this for anything but an electrolytic cap. This is a very old package design from the transition between through hole and SMD. The process for making the vertical axial style common now hadn't been perfected and it was briefly cheaper to cast regular axial caps into an epoxy block. No other component looks like this, it's a very distinct package and footprint from any other type of cap. No one tried to disguise anything, they really just thought this was the cheapest way to make a surface mount electrolytic cap.
  - Panzer04 2y ago
    That is cute as hell XD
- doctor_radium 2y ago
  I'd have to pull the drive to have a good look, but my memory is that the circuit board resembles the inside of a 1960's era transistor radio. Will hope you're right.
coder543 2y ago
> I'm a bit surprised there was no mention of semiconductors (mostly capacitors?) going bad on 1990's hard drives. I don’t think any kind of capacitor is a semiconductor.
- rzzzt 2y ago
  Dons glasses well etymologically... the "semi-" in semiconductor means "partial", something between an insulator and a conductor. A capacitor is an insulator between two conductors. (But this approach fails on the temperature coefficient of resistance test: capacitor ESR increases with temperature while semiconductors have a negative coefficient.)
dghlsakjg 2y ago
Capacitors aren't semiconductors, they are just regular components. Semiconductors actually are pretty stable long term. The capacitors that go bad tend to be the electrolytic ones, and there aren't a lot of those on things like hard drives.

jimmaswell 2y ago

Hm, I have some classic scsi drives still kicking in some old Macintoshes, maybe I aught to back them up. They're funny, sometimes they get stuck and I have to whack them with the rubber side of a screwdriver to start them up.

Panzer04 2y ago

Do HDDs have many electrolytics? Those are the main culprits for going bad, and are usually used for power electronics, not controllers/processing circuitry (they don't need the bulk capacitance that you'd usually use an electrolytic for)

dougg3 2y ago
There are indeed some aluminum electrolytics hiding on Quantum drives. They look sneakily like tantalum caps, but they're just cans hiding inside a plastic cover. Here's one where I accidentally broke the cover, revealing what's underneath: https://i.imgur.com/LdjUx3v.jpeg https://i.imgur.com/LdjUx3v.jpeg
- ComputerGuru 2y ago
  You can’t convince me that’s not intentionally disguised like that.
  - yborg 2y ago
    It's more likely so these could be used with a pick and place machine. They're obviously lytics if you look at the ends. I don't know why everything has to be a conspiracy these days.
  - mystified5016 2y ago
    No reasonable EE would mistake this for anything but an electrolytic cap. This is a very old package design from the transition between through hole and SMD. The process for making the vertical axial style common now hadn't been perfected and it was briefly cheaper to cast regular axial caps into an epoxy block. No other component looks like this, it's a very distinct package and footprint from any other type of cap. No one tried to disguise anything, they really just thought this was the cheapest way to make a surface mount electrolytic cap.
- Panzer04 2y ago
  That is cute as hell XD
doctor_radium 2y ago
I'd have to pull the drive to have a good look, but my memory is that the circuit board resembles the inside of a 1960's era transistor radio. Will hope you're right.

coder543 2y ago

> I'm a bit surprised there was no mention of semiconductors (mostly capacitors?) going bad on 1990's hard drives. I don’t think any kind of capacitor is a semiconductor.

rzzzt 2y ago
Dons glasses well etymologically... the "semi-" in semiconductor means "partial", something between an insulator and a conductor. A capacitor is an insulator between two conductors. (But this approach fails on the temperature coefficient of resistance test: capacitor ESR increases with temperature while semiconductors have a negative coefficient.)

dghlsakjg 2y ago

Capacitors aren't semiconductors, they are just regular components. Semiconductors actually are pretty stable long term. The capacitors that go bad tend to be the electrolytic ones, and there aren't a lot of those on things like hard drives.