Hi chaps.
Having recently picking up two dead 2008 iMacs, one is now working, however there is still one to repair.
I was told that they both had failed power supplies, and seeing how I intend to crack SMPS repairs, it was a challenge not to ignored.
Anyway, this PSU in question had already had someone having a pop at soldering.
The current problem is (at the very least) in the primary side.
Fuse is ok
MOV is ok
NTC is ok
Bridge rectifier is ok (~380vDC)
Fat filter cap is ok
Transformer FET is ok with high volt DC on Drain
What is missing are both the standby voltages, which are normally found on pins 5 and 9 of the output cable connector. Pin five is supposed to be 3.something volts, and pin 9 is normally 12v
I am suspecting that the inverter section would fire with these missing voltages.
My question as a learner, who still hasn't quite grasped standby circuitry is, "where can I trace these voltages back to, and is there any component or area in particular which should be checked?"
I'll include more photos as I take them. These are of an identical unit.
Having recently picking up two dead 2008 iMacs, one is now working, however there is still one to repair.
I was told that they both had failed power supplies, and seeing how I intend to crack SMPS repairs, it was a challenge not to ignored.
Anyway, this PSU in question had already had someone having a pop at soldering.
The current problem is (at the very least) in the primary side.
Fuse is ok
MOV is ok
NTC is ok
Bridge rectifier is ok (~380vDC)
Fat filter cap is ok
Transformer FET is ok with high volt DC on Drain
What is missing are both the standby voltages, which are normally found on pins 5 and 9 of the output cable connector. Pin five is supposed to be 3.something volts, and pin 9 is normally 12v
I am suspecting that the inverter section would fire with these missing voltages.
My question as a learner, who still hasn't quite grasped standby circuitry is, "where can I trace these voltages back to, and is there any component or area in particular which should be checked?"
I'll include more photos as I take them. These are of an identical unit.
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