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Help with 1040STF PSU

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Hi there. I recently got a 1040STF (US, 110V) and decided to give it a complete overhaul. The PSU was outputting 4.9V and 10.5V, but with some fluctuation. So I replaced all aluminum capacitors (8 total). After that I got a very stable 4.9V and 10.7V output, but yet far from the expected 12V. Anyways I decided to test the PSU and once I connected everything I couldn't even get the power LED to light. So I checked again and the PSU was dead, no output whatsoever.

Next I tested the rectifier and got 300+V, don't remember exactly, but though it was unusual.

I was wondering if perhaps more experienced ST users here that faced similar problem would help me fixing this PSU. Any suggestions on what I should check next?


Many thanks in advance!

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Interestingly ( or not ;) ), I had exactly the same problem as you but on a 240V PSU. Voltages down, so re-capped it. Voltages slightly better, but still not where I'd expect them. ST would power up once, FDD reading would be problematic and the PSU was generating a scary amount of heat. After switching off, it wouldn't power up properly again. There's obviously something else very wrong with the PSU. In the end I replaced it with an external ATX supply rather than work my way through it trying to work out what had gone bang.


Exxos makes some really rather fine looking PSUs for the ST, that was my fall back plan had the ATX idea not worked.

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