Electronics > Repair
Ferrus power fp250-710 power supply repair (mystery part)
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Jay_Diddy_B:
Hi,
This board that you are working on looks like a standby power. The input to the supply is red lead, +ve and the black lead, -ve. With a power factor correction stage there will be about 370V between those leads.

The board should be pretty close to the TOP223p datasheet or application note. I would try and trace out the schematic.

These will be connected to the main electrolytic capacitors in the power supply. Given the age of the power supply I suggest that you measure the ESR or simply replace the main electrolytic capacitors.

Regards,
Jay_Diddy_B
Thedarkmade:
Hello evreyone, I've the same issue, but I know this part is a TOP223P. Replaced by The TOP223PN, who is the same but the leedfree to comply with the ROHS, but it's the same datasheet.

I switch it with a new one but the part break explode instantly with the power ON. I'm trying to find out the root cause, but it can be really helpfull if you can tell me what's you've found on your side.

By the way the R106 on the power supply is completly exploded to and I can't figure what's the R value can be. Anyone have the schematic of this power supply, or the value of this resistor ?
amyk:
Check for other shorted parts nearby.

Also, a variac, or lacking that, a "dim bulb" tester may help with troubleshooting without blowing more parts.

Given that it appears to be a standard PC PSU, and quite a low-rated one at that (only 250W), if you can't fix the PSU you may try substituting a regular PC one.
factory:
SMPS and variacs are not a good combination, lower line voltage equals higher current through the switching transistor.
Some PSUs had/have auto line voltage detection for 110V/230V, if you are in a 230V area and you go from 0V to 110V and it sets for the 110V operation (doubler circuit), it would fry once you get head towards 230V.

Modern PC PSUs don't have a -5V output, also old PCs didn't require high power PSUs.

R106, is actually open circuit or just burnt? measure to confirm. Could the small cap near the TOP223 be open/dried out?

David
Vovk_Z:

--- Quote from: Thedarkmade on September 14, 2023, 04:07:36 pm ---I switch it with a new one but the part break explode instantly with the power ON. I'm trying to find out the root cause, but it can be really helpfull if you can tell me what's you've found on your side.

--- End quote ---
Have you replaced all the small electrolytes on the board?
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