iMac 20" A1174 dead, but +/-12VDC at PSU
Hi All !!!
Got an iMAC Model# A1174. 2006. 20" display. Last 4 of the SN are VU2S.
When you press the power button, NOTHING happens.
Disassembled the unit. What I discovered is: Power button tests good. If I DISCONNECT the multipin connector on the motherboard (logicboard?), then plug the power cord in, I hear the HDD spin up. No fans nor LEDs, just the HDD. if I re-connect the multipin connector on the motherboard, then plug the power cable in, nothing. Press the power button and again nothing.
With system normaled up but display and multipin connector removed I have the following on the PSU :
Grey wire 1 = +12VDC
Grey wire 2 = -12VDC
If I re-connect that multipin connector back into the motherboard, I get 0 VDC on those grey wires. With the multipin connector disconnected and the power cable plugged in, I can read various DC voltages (5, 3, & 12).
I have a bad feeling that the problem is possibly with the motherboard since the multipin connector has all the appropriate voltages on it before I plug it back into the motherboard.
Any ideas of how to test the PSU any further, or how to isolate this problem better?
THANKS ALL in advance!
Is this a good question?