Technical Support iMac A1419 820-4652 No Power First LED is on

[user61596]

Need help with iMac A1419, No Power
Already check big coil, no short.
Thermal Camera get no short.
Power key is ok.
Power supply Replaced.
1. What I have to Check first?
2. Can I try without CPU, or CPU mus be inserted.

 

[Ahmad Safari]

If there is no shorts, reprogram the BIOS.

 

[user61596]

If there is no shorts, reprogram the BIOS.

BIOS Reprogrammed now, no result no Power.
Can your please lookt this Video, why all VR PHASE GPUCORE and PPGPUCORE S0 SENSE shorted to the Ground, it is normal?

 

[user61596]

anyone?

 

[Ahmad Safari]

Yes, it is completely normal.
Your test is completely wrong.
Buzzer test is not correct for this and you need to measure the resistance value or take a diode test.
Usually, the resistance of this part is below 10 ohms, and the multimeter beeps during the Buzzer test and misleads you.

 

[user61596]

I foun short on CPU Phase, don´t know wich one of 1-4.
Cant find nothing with Thermal camera.

 

[user61596]

It was short on CA345.
Thanks for all.

 

[Admin]

It was short on CA345.
Thanks for all.

watch this video:
How to Ohm Check Laptop Motherboards using Digital Multimeters