PSU blues (soft power?)

[sharp]

Greetings everyone.
I have a problem with this tetris block psu. I repaired it a year or 2 ago. I recently went to power on after a hiatus for a while. It powered on, it gave the insert floppy prompt, put a floppy in, then while the floppy loading LED fluctuated, the screen flashed (official sharp x68k monitor) sporadically, flashing from black to white, seemingly switching refresh rates between 15, 24, and 31. the floppy drive sounded like a broken HD, just trapped in a phase, like a metronome.  I turned off the x68k, turned it back on, then everything seemed different, like the floppy drives were struggling for power. Got the floppy out, then turned it off/on, well not on then. It wouldnt come back on! the red LED lights up, but no green, and the fan is trying to spin but never starts, just twitches. I pulled the PSU out, and put in a good PSU, same story... I looked at the sub board, nothing was glaringly obvious. Any advice is appreciated. Thanks (^ u ^ )/

EDIT:
Oh, actually, the SRAM battery was a dud, but SRAM wouldnt be the culprit here, right? 

[sharp]

to put it plainly, I have 2 tetris block PSU's working perfectly, but when plugged into the lower board, soft power does nothing apparently, except for make the fan twitch every few seconds. PSU's alone, the fan's work perfectly, all voltages present.

I have looked at the "troubleshooting soft power" but I cant run the helpful diagnostic, & I cant make sense of the soft power schematic. (due to lack of understanding, not the designers fault)

I saw a previous topic http://nfggames.com/forum2/index.php?topic=5494.0 about a similar problem, but reversed (wont power off, instead of on). Although, english was not his native language it seemed, and he did not confirm if capacitors fixed it/what capacitors in particular if so. Can anyone confirm if the capacitors he showed on the bottom sub board are part of the soft power circuit?

Does anybody know how many layers the bottom sub board is? I noticed where the PSU power plug goes into this board, only 1 or 2 points of the header seemed to link up on the underside? (+5v IIRC?)

[NFG]

In my Compact, the capacitors on the motherboard were causing the system to partially shut down.  These old caps need a periodical replacement, and you're wise to do them all, not just a few.  I can't say that this is your problem, but failed caps are a definite problem for every X68000 machine (and, for sure, everything beyond a certain age).

[sharp]

Thanks for the advice Lawrence. I took the board off with the soft power switch? the bottom board. I hooked that up to the PSU isolated from everything else. After a while the PSU seemed to show signs of failure. Specifically on the 12 volt lines. They initially were present, but not long after the 12 volt lines continuously dropped.

Not really sure what to do... 
I just tested a diode D2, it seemed wonky, but it was in series with the transformer I think?
Hmm... I think I recall lydux mentioning something about D2.
Hopefully next time I report back it will be a success.

Thanks again. (^ u ^ )/