820-00281: No booting up but CPU/GPU warm with fan spinning.

[macRepairAmb]

I have this board, customer said it wasn't getting image to the display but did get image on external display. Once i started working on it, i noticed there was no usb-c activity on any of the port, which also meant no external display image. Started probing and noticed L7410 and L7421 (PPVCCGT_S0_CPU) were reading 0v.

Signals to U7410/U7420
PP5V_S0 - 5v
PPBUS_HS_CPU - 12.6
CPUGT_FCCM - 0.015
CPUGT_PWM1 - 2.57
CPUGT_PWM2 - 2.58

current pull by the board swings inconsistently between 1.20 and .91A

Any suggestions?

 

[2informaticos]

VCCGT refers to iGPU and doesn't come on when board boots.

USB-C ports switch to 20V?
3V3_G3H and PPBUS_G3H present?

 

[macRepairAmb]

USB_C does switch to 20v

3V3_G3H - 3.4
PPBUS_G3H - 12.6

 

[2informaticos]

Do you get PPVCC_S0_CPU?
If yes, check for USB activity and external video?

 

[macRepairAmb]

PPVCC_S0_CPU - 1.08
No usb activity or external video.

 

[2informaticos]

Looks like board doesn't really boot.
PPVCC_S0_CPU should change in few steps, untill 0.6V aprox.
Possibly bad CPU.
Try known good BIOS, just in case.

 

[macRepairAmb]

Tried good bios with same issue, and PPVCC_SO_CPU never steps down.

 

[2informaticos]

Ask the client how he lost internal image first.