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Sebasboy

macrumors member
Original poster
May 20, 2019
37
7
hello good day. got a imac 2011 27 inch here.

it came in with a problem.

if you plug it in. it would instantly trip the circuit breaker. i swapped the psu. and the inverter board and it stopped tripping the breaker.

but the following problem is still present.

if i turn it on. i hear a bong. but nothing on internal or external display.

checking the diagnostic lights. 3 out of 4 light up (with both the internal display present or removed)

the keyboard does not get turned on so i cannot perform a pram reset.

after suggestions of testing another gpu. i swapped in a 21 inch 2010 imac gpu in there including the heatsink for testing.

I did that. and now only 2 of the 3 lights went on.

so i swapped back the original gpu. and now only 1 of the lights turn on after i press the power. (fan spin and ramp up due to missing thermal sensors)

any input? I know if the 2nd light is off the motherboard does not see proper psu power.
 
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