Repairing Bestec TFX0250D5W

[JHPArizona]

Re: Repairing Bestec TFX0250D5W

I have one of these power supplies. The supply doesn't want to power up. 5vsb seems OK. I have a pwer supply tester. Sometimes when I connect the tester in while AC cord connected the supply will power up. Seems the power on circuit is not working correcly. The computer boots normally with a different bestec supply but wiring harness too short to mount ps in computer. Any help would be appreciated.

[JHPArizona]

Re: Repairing Bestec TFX0250D5W

OK, found that PS_ON is only 2.8v when connected to main board. See that comes from the vertical board.

[rogfanther]

Re: Repairing Bestec TFX0250D5W

Hello,
Pics from your psu, please.

[momaka]

Re: Repairing Bestec TFX0250D5W

I have one of these power supplies. The supply doesn't want to power up. 5vsb seems OK.

Did you measure the output voltage with a multimeter to see if it's giving proper 5V? If yes, try putting a load on it, like a 12V 20 Watt car headlamp or MR16 halogen bulb. If the 5VSB croaks and does not output 5V with this load, suspect the output caps on the 5VSB are bad. Possibly the small "startup" cap for the TNY IC too.
If 5VSB is OK with load, the rest of the output caps could be bad too. Either replace them all or test with a "cheap" cap/ESR/component tester. At least that would be a good starting point. Remember, caps don't have to look bad to actually be bad, particularly when it comes to lower-tier non-Japanese brands like this Bestec has.