Is this common, or am I just unlucky?

[Tincanalley]

So, I fired up the 5150 today and was trying to run a just opened cardboard mailer I got back in the early 80s (yeah, I never opened it). Inside was a demo of Lotus Freelance and I just had to run it. Upon running the first disk, it wanted the second in the B: drive. I complied and....nothing. The drive was dead. I took it out and discovered it wasn't spinning and so I pulled the motor control board off the back. On close inspection, the two 47uf electrolytic caps were bad and had leaked, long ago, and one actually ate all the solder and it fell out of the holes on the circuit board. The second one didn't go as far, but it did leave a bunch of corrosion. I have no idea how it worked this long with how bad the connections and traces are.

I dove into my box of drives and found three matching drives. Two of them had the exact issue of the the electrolytic caps leaking and one the cap actually collapsed like it had been crushed. The third drive had a slightly different layout and different brand electrolytic caps and brought the drive back to life. Now I need to replace all the caps on the three boards and repair any traces, etc.

So, has anyone else seen this on the motor control board of the TM100-2A?

 

[VERAULT]

i havent seen them fall off but its typical on amiga 3.5" drives to have the caps go leaky and the drive fail.

 

[Al Kossow]

Yup it's common.
Almost all of the early Sony CDROM drives have died with electrolyte leakage and trace damage
and most 3.5" floppies in PS/2 computers have problems.

 

[Tincanalley]

Yeah, I get it that they dry out, but the fact that three drives had the same leakage from the same caps...?? Makes me think there was something wrong with circuit design. The only one that works has a few different components and different brand and size of caps. All drives were from 1983.

Oh well. Will be cleaning up the board traces and replacing the caps tomorrow. Once I have them all running, I'm going to break out the scope and align them. If all goes well, I will have three spares and none being scavenged for parts.

 

[Tincanalley]

Well I managed to fix one board today. The capacitor that was bad looks like it was crushed. Since the board sits on the back of the drive, it wouldn't be hard to see someone slamming it into something and crushing it. It was fully shorted, the other 47uf cap was at 14 and the 1uf cap was dead on, but I replaced it anyway.

Since I have been doing lots of audio work lately, I have a crapload of Nichicon KWs, so I used those.