Electronics > Repair

Dell DA2 12V 18A PSU repair P/N M8811

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simontay1984:
I have aquired a Dell SX280 from a friend that wasn't working.
I opened the PSU (part number: M8811) and found that some SMD transistors on a small daughter board are fried.
Its part of the feedback circuit. I think some pins on it got shorted to the metal shield/heatsink.
They're so badly burned I can't identify the part numbers.
I bought a replacement DA2 on eBay for £10 with the intention of looking inside to try and identify the components so I could fix the other PSU but the little daughter board in it is different.   >:(
The part number on the case of the working one is N112H. The computer works fine with the new PSU.
Does anyone have a working DA2 PSU with part number M8811 that they don't mind opening to get the part numbers of the components on the little daughter board. That would be much appreciated :D I have attached some photos of it showing the fried components.

simontay1984:
Some more photos of board attached cos of 2000KB limit.

simontay1984:
An update:

The side with the 4 pins and the burnt transistors is on the primary high voltage side.
They're not likely to be just any 2SC, 2N or BC548/558 type. There are 100s of different transistors out there.
They probably need to be high voltage ones. Q201, Q202, Q203, R201 and ZD201 are what is burnt. R201 is completely black. The value of that resistor matters. I couldn't find any schematics on the web of this PSU. OEM is Delta. The model number of this little board is STDC-003.

The other working PSU doesn't have those tiny transistors. The components on it's daughter board are completely different. There is an IC and an opto-isolator as well as the transformer. The side with 2 pins on this is 3 pins on the other working PSU.

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