Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

What burned the "switching transistor " in a Power suppliy ATX ...

Status
Not open for further replies.

interneti

Member level 4
Joined
Nov 6, 2011
Messages
69
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
1,715
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

how to fix this problem please ?

THANK YOU !..
 

powersupply1.jpg This transistor in this photo are in shorted, i need same help

THANKS !!
 

i checked all capacitor in the board, but still the same problem,
i replace again the transistor and again they burned and the fuse so.
 

Give me model number of that ATX power supply. I will try to find circuit. Then we will see. Capacitor in bottom right corner is changed?
 

The model number is LPH 200W, thank you!
 

@ 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.

wbr
 

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
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top