Hello !
can anyone help me with any advice,
I am repairing a power supply ATX ,
I found in the primary side a switching transistor shorted (BU508A), i replaced it with a new
transistor but when i turn on the power supply another switching transistor burned .
I check all diodes and capacitor in primary section, but still the same problem
@ interneti ,
have post photo is dated 2011-06 10. you want to repair power supply in this photo? if yes then you have changed bulged Capacitor in bottom right corner ? as tpetar ask.
Is there some other numbers about model? For LPH200W there is nothing! All points on low cost chinese power supply.
You should change that capacitor in bottom right corner, check other big capacitor next to that in bottom right corner.
Specialy check that capacitor on bottom side of his body! Maybe he leaks on bottom side.
I supose that you already checked bottom side of pcb from shortcircuit and things like that. Is there on bottom side some SMD parts? How is their status on eye, how they look ?
When you changed transistor you pay attention to isolate them from heatsink and from each others?
You put some thermal grease between transistor and heatsink ?
The photo that i upload is not exactly the power supply that i am repairng but is the same power supply.
I have checked all capacitor in the priamry and secondary sections they are all good. when i replaced the second transistor
and i switch on the power supply the transistor were very hot and burned ,
The transistor are isolated from heatsink . again is the same problem
i want to thank you very much all
Please provide more details about the control ICs used for this power supply.
Check also some ATX power supply schematics here: https://www.edaboard.com/threads/218905/