VAX 4000-500 PSU Overload?

Tiffe In the light of what you say below, do you mean you only changed this one, or did you change all of the ones on the logic board? Does that include the really big ones too? Nothing at all was wrong with your idea. I had indeed followed your advice on the 12V board, on the basis that I could reach them and that it seemed to be the 12V side that was having the problem, so implying that other parts of the PSU were OK. I did not change any on the 5V side as that side seems to be OK and I don't really like the approach of pulling and soldering them them all desing Yes, and I may yet have to change those on the 5V side, because after posting the good news, I had one brief episode where the PSU switched itself off again after running for about a minute. On powering it up again it worked for a good hour without issue. So perhaps I should bite the bullet and replace those too, and also the other small electrolytics on the logic board too. However, I don't think I will replace the really big ones. Generally, I get the impression that these big ones suffer fewer problems, certainly their ESR is fine. I am also reluctant to change them because they are generally connected to large heat-sucking planes, making them hard for me to desolder without making a mess of the board and possibly damaging it too. Regards Rob