Amiga 1000 Capacitors

[SportBikePilot]

I'm curious how real of a problem this is. I'm starting to think there's no question about it.

I haven't really used my A1000 in a couple of years. Started it up this evening and I got ONE good boot out of it. Shut it off, turned it back on, and it won't read a Kickstart disk that I have no reason to believe is good.

I use an Amiga Parciero II with it, so I don't normally use Kickstart. But it was part of my tinkering to find the problem. I also found it doesn't play the little musical tune it usually plays when it starts up. It also doesn't appear to see the external floppy disk drive.

It boots into AmigaDOS (obviously the WCS is receiving Kickstart), it reads the RTC on the Parceiro, and then hangs. No mouse movement. Keyboard responds, CTRL+Amiga+Amiga reboots it.

After a while of leaving it to sit on, I soft rebooted it, and it now shows corrupted characters on the screen, and still hangs.

I'm guessing I got the last of the capacitor(s) on the board with that one good boot, and now I've got a problem.

Any commentary? I'm a telecommunications engineer by trade, an amateur radio operator and an electronics hobbyist, so swapping capacitors isn't a problem. I've already ordered kits for my A1000 and A500 from Retro Rewind, so I should get those in a few weeks.

I'm more or less asking if anyone's come across bad capacitors and what symptoms you saw.

Computer powers on, LED flashes three times and screen displays dark grey, then white, then tries to boot. Won't boot off diskette, boots to a hang with the Parcerio II (which is a STELLAR product).

Appreciate any input!

Chris

[SportBikePilot]

Just wanted to follow up with some findings on this:

I found a broken leg on the PAULA IC. I've no idea why it broke, but it did. I removed all three custom ICs and used deoxit on the sockets, and repaired the broken leg on the PAULA IC using a leg from an old EPROM.

Reinstalled all of the chips and my system is now working properly. It doesn't play the musical tones when I turn it on, but I am using an Amiga Parceiro II and a 68010, so maybe that has something to do with it. Whatever the case, it's working properly again.

While in there, I inspected the capacitors and while I did order the replacement kit, at this time I'm electing to hang on to it and not install it. It was clearly not the problem, and I've learned the hard way too many times not to try and fix things that aren't broken. There is zero evidence of leakage, and keep in mind these are all through-hole capacitors from a time before the "capacitor plague". That's what made me decide to open the thing up and see if it was something else, which it was.

Hope this helps someone.

[screwtop]

Glad your 1000 is working again! I totally hear what you're saying about not fixing it if it's not broken...I recently bent (but thankfully didn't break) a pin on the 68000 on one of my A500s, after swapping it while troubleshooting another machine. I'd broken the socket while prising the chip out, glued it back together, and a tiny amount of glue must have wicked into the wiping contacts on one pin. A simple desoldering job can get unpleasant if things don't go well!

The SMD capacitors in the A600/1200/4000 are notorious, but I haven't seen too many issues with caps on the 1980s Amigas. Do you have (access to) an ESR meter? I believe those can generally give indicative results with the caps in-circuit.

[SportBikePilot]

Agreed, the SMD capacitor Amigas definitely need capacitor replacements as soon as they can be done.

I don't think the A1000/A500 really need to be touched unless there's definitive proof of a problem. I ordered the kits from Retro Rewind, then discovered I don't really need them. But I'll hang on to them anyway, good to have around. At some point I think it's more likely for the caps to dry up rather than leak.

I don't have an ESR meter. I am also leery of "in circuit" testing of certain components. I suppose if you have a good out-of-circuit reference, that would be better.

Now to try and find an A1020 5.25" disk drive...

[arttu80]

Very nice that it is working again! I mostly agree on capacitor replacement subject, but just recapped my A1000 (PAL) because I was having ailing sound issue with it and doing recap cured that. So maybe soon you'll have to do it too.