820-00840: Not powering up and cpu warm.

[macRepairAmb]

Hello Jents,

Have another board here that's not powering up. Had some corrosion/liquid damage on and around the backlight caps C8473 - 8469 and 8461 and 64.

PM_PCH_PWROK - 3.3
PM_PCH_SYS_PWROK - 0.0
ALL_SYS_PWRGD - 3.22
CPU_VCCST_PWRGD - 0.997
SMC_PM_G2_EN - 3.4

PP3V3_S0 - 3.3
PP5V_S0 - 5.1

Anything else i can check?

 

[2informaticos]

"PM_PCH_SYS_PWROK - 0.0 "
Do you get voltage at L7730?

 

[macRepairAmb]

L7730 - 1.05

 

[2informaticos]

Remove R7745 and check if PM_PCH_SYS_PWROK is still low.
Be sure R7841 is OK.

 

[macRepairAmb]

Removed R7745, PM_PCH_SYS_PWROK still low
R7841 is good, 98K

 

[2informaticos]

Could be a problem with U7800.
You should check all power good signals received by U7800, supposed to appear before it releases PM_PCH_SYS_PWROK ; page 60, left side.

 

[macRepairAmb]

Replaced U7800 and i now have PM_PCH_SYS_PWROK @ 3.28v. But still not booting up.

 

[2informaticos]

Check if PLT_RST_L comes on.
If yes, try known good BIOS...

 

[macRepairAmb]

PLT_RST_L - 3.3
Flash good BIOS (one i've used before), still not booting up.

 

[macRepairAmb]

Battery does charge as when the battery is connected, the unit is pulling about 2.2A

 

[2informaticos]

Liquid spill on backlight area could affected some data line.
Probably CPU problem now...

 

[macRepairAmb]

Yeah that's what i'm thinking also. I'm going to check a few other things along that area before i quit on this board. Thanks for the assist.