Macintosh IIsi Powersupply troubles.

[catboyjack]

Hi friends,

I recently preformed my first successful recap of a Macintosh IIsi and it's Sony power-supply.

Unfortunately for me, shortly after my victory I heard a "switch" and the system turned off and I can no longer get the machine to stay on for more than a few seconds.

I'm new to this sorta thing and I have ZERO idea where to start diagnosing power-supply issues so if someone could lend me a hand it would greatly be appreciated

(I completely recapped the powersupply, gave it a bath in the dishwasher to remove the corrosion, then completely submerged it in 99%IPA to displace the water. I let it dry completely overnight before testing.) It seems like something is causing the relay to open, but I don't have any idea what it could be.

 

[robin-fo]

It‘s a bit hard to see in the video, but did you also recap that tiny daughter board inside the PSU?

Maybe there is a short somewhere, causing the PSU to shut itself off.

From what I can see your EGRET and therefore also the 5VTrickle from the PSU are working properly.

There is a schematic for the SONY Power Supply (which you probably have) inside the BOMARC IIsi schematics.

 

[catboyjack]

It‘s a bit hard to see in the video, but did you also recap that tiny daughter board inside the PSU?

Maybe there is a short somewhere, causing the PSU to shut itself off.

From what I can see your EGRET and therefore also the 5VTrickle from the PSU are working properly.

There is a schematic for the SONY Power Supply (which you probably have) inside the BOMARC IIsi schematics.

Yeah I recapped the daughter board. I found to be what looked like two solder joints that were touching on the bottom of the PCB so I'm trying that right now.

 

[catboyjack]

The issue has been resolved for the most part!

I boiled the issue down to the soft power circuit with some help from CJ in the Vintage Apple discord server. I redid my recapping job on that board and it fixed it (mostly).

Unforutnatly it *still* will just power off but I can get the machine running for 45> minutes, but I blame that on the really roughed up daugherboard and my amateur soldering skills.