No power on, no trickle voltage on logic board, blown Mosfet

Hi Mayer , yes indeed that is the iMac in question. Swapping the power supply has already been done and did not solve the issue sorry to say. All voltages into the logic board were correct with the original power supply also but swapped a new one in just in case.

Let get this straight, you replaced the power supply but get NO diagnostic LEDs?

This got confusing because you used two questions on the same problem but provided different information in the two. Then when it was caught (the duplicate question) they were combined. My answer was to the question that was deleted. It did not contain the information this question did on the power supplies. So PLEASE just ask the question once and if you need to add updates to the original question.

Not sure what you mean. I have posted two different issues on two different iMacs at different times. This one relates to an iMac that does not power on , no LED at all despite replacing the power supply. The thread above is quite strait forward.

To make it clearer.

iMac tested - No power on.

Screen removed - No LED lights at all.

Power supply swapped with known working one - No LED

Power on test - Blew mosfet as described above

Removed logic board - Replaced mosfet

Retested - No LED same original condition however the replaced mosfet is staying intact for now.

My iMac 2638 has the same issue. I bought a known good power supply, installed it, and the situation remained the same (no power, no boot, no fans, no diagnostic-LEDs at all...). Any ideas on a next step for this?