iMac (Retina 5K, 27-inch, Late 2015) Yes/No?

[techgeeksna]

Good Day Guys, im not sure if ill be able to get some assistance on this iMac problem but here goes nothing.

I have a 5k 27inch iMac that does not want to power on. The PSU is good (tested on another imac) and the diagnostic LED's are all off. Anyone have any idea where i can start looking?

 

[aprendiz]

I guess is 820-00291, so no schematic available, have one here with same symptoms, the problem here was because a shorted USB port(dead TPS2561), 5V rail shorted (dead ISL62383), burnt CPU Vcore rail (dead ISL95828)..

All parts replaced and no improvement, no schematic so i cant go furter.....

12v present
PP5V_S5_LDO present
3.42V present
3.3V S5 no present...

 

[dukefawks]

First would be to check for obvious shorts. The first LED is usually powered from 3V3_S5 so it may be very simple issue.

 

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I have the same problem, however, my iMac show the caps lock light and make the noise when turning on but the display does not show anything, anyone has a solution?