820-3115-B power loop

[dhz1nn]

I have a 820-3115-B with me, it does have a green light, the fan spins on and off every 2 seconds.

PPBUS_G3H - 12.63V
PP3V42_G3H - 3.49V
PP5V_SUS - 5.077V (goes to 5.133 when it tries to turn on)
PP5V_S3 0V (goes to 2.6 - 5v when it tries to turn on)
PP5V_S5 - 5.077V (goes to 5.133 when it tries to turn on)
PP5V_S0 - 0.01V (goes to 5.1 for 1 second when it tries to turn on)
PP3V3_S5 - 3.33V
SMC_PM_G2_EN - 3.48V

It is drawing 0.017 amps from my power supply and 0.198 when it tries to turn on.

No water damage or visible damages on the board.

Can someone help me solving that problem?

Thanks

 

[2informaticos]

First of all, welcome to the forum!

ALL_SYS_PWRGD pulsing too?
Try to start in SMC bypass.
Also try the board alone on the desk; no cables connected, apart of DCIN board.

 

[dhz1nn]

Thank you for the welcome.

I tried starting it in SMC bypass as well as the board alone on the desk but it did not work.

ALL_SYS_PWRGD is pulsing 0 - 3.327V

 

[2informaticos]

CPU VCORE pulses too?
What about PLT_RESET_L?

 

[dhz1nn]

PPVCCSA_S0_CPU - pulsing from 0 - 0.908v
PLT_RESET_L - pulses from 0 to 0.131v
CPUIMVP_TONA - 12.45v
CPUIMVP_TONB - 12.41v

 

[2informaticos]

=PPVCORE_S0_CPU_REG sounds more like VCORE power rail than PPVCCSA_S0_CPU .

 

[dhz1nn]

PPVCORE_S0_CPU - 0V
PPVCORE_S0_CPU_PH1- 0V
PPVCORE_S0_CPU_PH1_L - 0V
PPVCORE_S0_CPU_PH2 - 0V
PPVCORE_S0_CPU_PH2_L - 0V

 

[2informaticos]

One test point is morte than enough.
Do not waste time measuring same thing in more points...

Check R7402/03.

 

[dhz1nn]

R7402 - 149.4K pin 1 - 12.45V, drops to 0.619 when it tries to boot up // pin 2 - 12.64V (after around 10 seconds, it drops to 0V and goes back to 12.64)
R7403 - 181.7K pin 1 - 12.41V, drops to 6.45 when booting up // pin 2 - 12.64V (after around 10 seconds, it drops to 0V and goes back to 12.64)

 

[2informaticos]

Compare diode mode readings on CPU coils with good board.
Boards stays on if RAM is removed?