Hi. A friend asked me to fix his old iMac that stopped working. I opened it up and found out that the SMPS IC was burned so badly that it was impossible to identify the type. After a lot of research I discovered it was a KA5S12656: I bought some of them from AliExpress, keeping my fingers crossed. Now I get the correct voltage on the main cap and on pin 3, but nothing happens when I push the front switch: I guess there should be a control voltage sent from the logic board to pin 5 (soft-start) but I can't see nothing there. Following the service guide's Troubleshooting suggestions, I checked the logic board looking for trickle 5v on J9 and DCU -1,2v on C10: nothing at all.
I checked several caps on both analog and logic boards, and the values seem correct. I didn't find a proper service manual with schematics, just the aforementioned "take-apart" service PDF.
Any suggestion and help would be highly appreciated. Thanks in advance.
I checked several caps on both analog and logic boards, and the values seem correct. I didn't find a proper service manual with schematics, just the aforementioned "take-apart" service PDF.
Any suggestion and help would be highly appreciated. Thanks in advance.
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