Trobleshoot PC Power Supply

[fais_78]

Good day all,
recently i tried to repair my Pc Power supply,found dead body of lizard which probabaly contributed in the Short Circuit.Both protector caps (insulated)beside the 470µf found totally burn out,fuse 8A was cut off.Yet,after replaced all mention parts the Power Supp still down.I noticed that the heat sink which attached to the power transistor contain with 120V.Is there any possible for heat sink to conduct current instead of heat from the base of transistor?Is there any tricks to recognize transistor's condition?Thanks for the info,may ---(him) speed ur electronic skills.
ciow!

 

[rascabuche]

Hi,
I had the same problem the other day and the best i had to do was replace with a new one. It will cost double the price of a new one to repair.

Ras

 

[sinip]

Good day all,
recently i tried to repair my Pc Power supply,found dead body of lizard which probabaly contributed in the Short Circuit.Both protector caps (insulated)beside the 470µf found totally burn out,fuse 8A was cut off.Yet,after replaced all mention parts the Power Supp still down.I noticed that the heat sink which attached to the power transistor contain with 120V.Is there any possible for heat sink to conduct current instead of heat from the base of transistor?Is there any tricks to recognize transistor's condition?Thanks for the info,may ---(him) speed ur electronic skills.
ciow!

Transistors should be insulated from the heatsink. The best way to check the conditions of those transistors would be to desolder them and check it out of the circuit, because sometimes checking in-circuit can give you false results (unless you know what to expect). Also, ATX PSU will NOT start unless it is inside computer or you connect green wire (there is only ONE green wire) in ATX plug to GND. Check also 5V stand-by oscillator, check ALL semiconductors on primary side.