iMac 27 inch 2015 fan spins , no shime no video

[Don Anton]

Hi all,

I got this iMac 27 inch 2015 fan spins no chime no video.

when i press the power button second LED light present, and then restart by inself stay on but no chime no video only 2 LED lights on the board. I recon before we consider about 3rd LED we should get chime.

Tried SMC, PRAM reset and tryied with out rams no beep or any sound at all. No usb mouse light. Any suggestions?

 

[Don Anton]

Also I replaced the power supply to check still same.

 

[2informaticos]

What is the 820-xxxx board code?
It is always required.

Any history available?

 

[Don Anton]

HI its 820-00292. History no any damaged. Suddely black screen.

 

[2informaticos]

See if 3478 and 00291 help you in the repair process.
No schematic available for 00292.

Chrck if CPU power supply gets 12V when powers on.
Power FET of this rail fails a lot...