820-00967 - LED 1 only

[Palhano]

iMac won't turn on, only LED 1 lights up!
The logic board had a short on the 12V line. I discovered it was QD330, replaced it, and fixed the short.

There was oxidation on C5913 and Q8510. I replaced everything, but to no avail.
The PP0V85_ENET line in diode mode has a value of 0.080. I lifted the L8510 to isolate an area. On pin 1, I get 0.500, and on pin 2, I still have 0.080. Can you tell me if this measurement is correct?

I'm using XinZhiZao's schematic!

 

[2informaticos]

Do you get any pulse on other LEDs?
Also check for pulse at 12V_S0 and other secondary power rails.

Remove the CMOS battery, to allow automatic turn on.

 

[Palhano]

I have no pulse on the other LEDs.

The 12v_s0 line is stable at 12v.

I have stable 3v3_G3H and 5v_g3s, but I have no voltage on any of the S5 lines.

I'm testing without the battery.

 

[2informaticos]

I don't have such board to compare readings, sorry.

 

[Palhano]

I assembled the iMac to return to the customer, and like magic, it turned on! I'll continue testing and provide feedback.

 

[Palhano]

The device turned on normally. During testing, I restarted and reset the PRAM, and it came back without BKL and the cooler was running.

 

[Palhano]

After the SMC reset, the screen's blackout came back. I ran HWmonitor and it's showing the display sensor triggered. I'll try to find a cable to test it.