DECStation 5000/120 PSU (H7286-AA) troubleshooting info?

[nadaveiron]

Hi folks,

I'm trying to resurrect a DECStation 5000/120 that I got in an unknown state. For starters, it won't turn on. The fuses are good, and the capacitors in the input section of the power supply look good on visual inspection (no signs of smoke/burns, bulging etc). There is one bulged electrolytic capacitor in the output section. That said, I can't find any schematics for the PSU (H7286-AA). A quick googling did not uncover schematics or much info on this PSU. Any tips here? Does anybody have schematics? There are tested ones for sale on ePay, so I may fall back to that, but figured I'd ask first, in case there's an easy way to fix it.

Nadav

 

[nadaveiron]

One correction - it's H7826-AA, though I suspect the lack of responses is not a result of the typo.

 

[jplr]

Sorry if this post is unrelated. I had a power problem on my VaxStation. On close visual examination indeed some caps had bulged and leaked but there was also a tiny diode that was burned and a tiny transistor with a suspicious color.
The problem for me was that these components were not really accessible.