A1708 820-00840-A NO DISPLAY

[NIKHIL@1997]

HI,
I have a A1708 mac...part no is 820-00840--A
in my c type reader its take 0.465 ma
all coil voltages are active...but
PPVCCGT_S0G_PH3
missing (there is no voltages on L7410,L7420,L7430)

ALL_SYS_PWRGD

Get 3.2 v

PM_PCH_SYS_PWROK

get 0v

PM_PCH_PWROK

get 3.12v

Then i trace

PM_PCH_SYS_PWROK this is the pwrgood of U7700..there is no voltage on 20th pin of U7700.... PP1V_OPC_S0 I get 1 v WHAT NEXT...?

 

[2informaticos]

"PPVCCGT_S0G_PH3
missing"
iGPU core voltage will not appear, until high graphics load is detected.

What is CPU core voltage (L7210/20)?

 

[NIKHIL@1997]

L7210,L220 Gets 0.96v

 

[2informaticos]

Stuck on 0.96V?
Check it after 10-15s.

PM_PGOOD_CPUVCC comes high?

 

[NIKHIL@1997]

yes stuck on 0.96 v
PM_PGOOD_CPUVCC gets 3.3v

 

[2informaticos]

Check if U7800 (1 OF 10) gets all signals from left side (pag 60).
Also check PM_PGOOD signals listed bellow that area.