Apple IIgs power supply.....no more

#1 Wed, 20 Oct 2010 - 15:48 68kMLA

So I got an apple IIgs about two days ago and I got it all set up and running nicely. But yesterday when I was making disks for it disaster struck. here’s what happened:

I had the monitor off and the IIgs was on. There was three disk drives plugged in a chain (800k, 800k and a 5.25 dives) about five seconds before the power supply died I heard the IIgs trying to access the 5.25 disk drive it was a “clack clack clack” noise. Then in a cross between gears grinding and a really loud cap gun the power supply blew and the magic smoke began to come out.

I removed the power supply and got rid of it (couldn’t stand the smell). My question to the group is what caused it? I had a look at the IIgs board and it looks fine. There were two cards in it. An Apple memory expansion card and a clock card and I was using GSOS 3.1. What it the power supply or something more sinister.

#2 Wed, 20 Oct 2010 - 16:51 68kMLA

Capacitor in the power supply exploded. See the csa2 FAQs: Apple II Csa2 FAQs: Power & Cooling, Part 17/25

#3 Sun, 24 Oct 2010 - 22:59 68kMLA

so was it because there was no fan in it?

#4 Sun, 24 Oct 2010 - 23:40 68kMLA

http://www.applefritter.com/node/23900

This could also have been a cause of the PSU failing .

so was it because there was no fan in it?

I don't recall the IIGS model suffering from overheating issues, like a Plus, etc. It would be interesting to know if they did.

#5 Mon, 25 Oct 2010 - 00:08 68kMLA

Old machines that sat around for ages tend to pop a capacitor after they are on for a short while. One of my mint IIgs systems died after 30 minutes of use after sitting in somebody elses basement for many years. It was cheaper to get a replacement then to fix the old one, but I kept it for when getting a replacement will cost more then fixing the dead one.

If the capacitor burned it was probably a small one, easy to find on the PCB and probably also easy to replace. My old PS has a dead short somewhere but nothing is visible and no smoke came out.

#6 Mon, 25 Oct 2010 - 23:54 68kMLA

Scary. I had a look on my IIgs motherboard the other night. There's no sign of deterioration of the caps there, but now I'm worried about the power supply. Is it worth opening that up to possibly change the caps prophylactically?

#7 Tue, 26 Oct 2010 - 02:47 68kMLA

...but now I'm worried about the power supply. Is it worth opening that up to possibly change the caps prophylactically?

Prophylaxis on the power supply is definitely in order. The big filter cap (the rectangular one) is the one that most often goes bang.

#8 Tue, 26 Oct 2010 - 16:58 68kMLA

Hm, I thought I might. I'm a little concerned about mucking around with capacitors in a power supply, how do you discharge them safely?

Guess I'll do the power supply lead thing at the same time.

#9 Thu, 28 Oct 2010 - 16:40 68kMLA

I have a power supply from the 1st iigs i got its also bad.....anyone have a take apart guide?

#10 Sun, 7 Nov 2010 - 03:14 68kMLA

Hm, I thought I might. I'm a little concerned about mucking around with capacitors in a power supply, how do you discharge them safely?
Guess I'll do the power supply lead thing at the same time.

http://www.howtodothings.com/electronics/how-to-discharge-a-capacitor

that should give you a heads up on what to do.

but from what i have seen a blown cap is normally discharged already.

the high-voltage capacitors that are not blown are the ones you got to watch out for.