vbug wrote on 2025-01-26, 09:11:Hi everyone, I have some old toshiba T series PSU not working, model PA2478U, 18V 1.7A, and I would try to repair them. There is […]
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Hi everyone, I have some old toshiba T series PSU not working, model PA2478U, 18V 1.7A, and I would try to repair them. There is no current at all on the output. First I checked the output cable, it is in good condition. On the inside everything looks in perfect condition, no oxydation, no bomby capacitor, the 2 fuses on the 220v side are okay. I have no idea of what could be wrong with those PSU, so any suggestion or idea would be welcome. Thanks !
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Right, looks like I missed this. I fixed one of these a couple years ago and I thought I took pictures but I can't find them or anything written down for what I did.
Looking at yours on the underside of the PCB there is clear evidence of electrolyte leakage which has started damaged traces. You need to clean all that up.
The big high voltage cap does not fail. Those two big brown caps on the DC side are good quality ones and they were not leaking on mine.
My PSU looking at the cap codes, it appears I replaced the C10 capacitor (35v 47uF, at the edge of the PSU PCB in between those two sideways mounted sub-boards) with a modern rubycon.
I also replaced C13 (25v 220uF, by the two big DC capacitors under the heatsink, by the blue&yellow inductor thing) and from what I recall that was the bad one that had leaked everywhere, also replaced with a modern rubycon cap.
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Hopefully your PSU has the same problem, make sure to clean up all the electrolyte / brown that you can see with IPA.