After replacing all Caps including C7, I've reflowed every joint on the solder side of the PSU and it came back to life. The Apple IIe was a PAL version (820-0073-B) and showed following problems after repairing the PSU:
- no Power LED lit, no beep, PSU wasn't audible clicking -> Silence
Solution: Capacitor C17 and C15 shorted -> replaced C9, C12, C17 and C15 with 10µF 50V 85 electrolytic capacitors = board fully functional
After reading David Finnigan's New Apple II User's Guide, I've decided to revieve my dad's old IIe. I remember, back when I was a kid, this was his most priced possession, quite litarally. I've grown up in the Russian occupied part of Germany and at this time in the 80's, computers - especially Apple II's - were pretty much not accessable for people or insanely expensive.
Anyways, I've kept the IIe safe and sound for about 23 years now, but after hitting the power switch a few days ago ... nothing, no beep, no power light, no board led. On the audible side of things: no chirping, no clicking either, just plain silence.
After a bit of reading, the culprit seemed to be the PSU and after initial testing of the board connector, all outputs measured 0 to 0.5 Volts. As I understand, the Astec PSU is an early switcher, but doesn't need a load on the outputs to get going?
At first visual inspection, the caps on the low voltage side seemed to be quite cooked over time, and with no ventilation in the PSU case, I don't wonder why. How it seems, if one of the caps would have failed, there should be only one or 2 rails missing, but not all of them. There are 2 RIFA filter caps next to the AC plug, which showed cracks in the casing but were not blown. The AC fuse was still intact. Looking at the board and the backside, no visible burn or scorch marks, no signs of cracked or cold solder joints anywhere. But because the caps are nearly 33 years old (IIe 1982), I decided to do a complete recap, all electrolytics and the RIFA's, too. Said and done, I triple checked every cap I've worked on and fired it up - still silence. Well, at least no smoke.
I've gone through all the usual repair tips listed here in the forum and on some other sites, but I cannot figure out whats wrong with it.
Here's the story so far:
- PSU: Astec AA11042B (699-0161-A, 240V-50Hz-0.5A-70W)
- no noise, chirping, buzzing etc. on power up, no smoke either
- visually checked components and boards, nothing unusual
- replaced all electrolytics with exact matching types, except C7 (listed as 220µF/10V, built in was 220µF/63V and replaced with 220µF/25V)
- replaced RIFA X2 line filters, 1x .1µF and 1x .47µF @ 250V/275V
- Fuse was/is intact
- L+N board connectors = 230VAC (Europe)
- Switch and Cord intact
- DB1 Bridge rectifier intact: 230VAC in, 330V out
- No output on board connector J14, Pins 3, 4, 5 and 6
- checked resistors and diodes for shorts, seemingly ok (could have missed some)
... For now, I'm a bit lost. Since all low lines are missing, my guess would be some fault in the PWM circuit? Honestly, I didn't want to test any further on a live psu without directions and knowing exactly what to look for.
A little help would be greatly appreciated!
PS: I don't want to switch PSU's or replace it with a modern ATX one, the IIe should stay the way it was when my dad used it. Otherwise there would already be an ATX inside