820-00239 - Not Booting

mccafe

Member
Hello guys,

I have a laptop that does not boot and it only tries to turn on when the battery is disconnected.

Corrosion on PP5V_S0_KBD on the keyboard/fan connector. Cleaned up and fixed some of the pins. One of the redundant PP5V_S0_KBD pins are burned and not connected, will fix later.

Little corrosion around Q6000/Q6050 - insignificant amount. Cleaned up with alcohol, reflowed quickly.
Corrosion around U5256.
Lots of corrosion around U8192, U8190, U1910 - I understand there is a lot going around this area. Cleaned reflowed, replaced R1343, R8190.

Fans spin
PPBUS_G3H = 13.1v
CPU Vcore is present
GPU Vcore is present
No display internal or external
USB mouse I believe shows activity, however we need to confirm this

How do I begin troubleshooting? I don't have any donor boards for newer models yet, but they are on the way.

Picture attached.
 

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2informaticos

Administrator
Staff member
Very uggly that photo; a PlayBoy poster looks better...

Corrosion on CPU area makes worry about its integrity.
But if you can confirm USB activity for sure, at least CPU core should be good; not so sure about iGPU.
Use an USB OSX pendrive with Link LED to confirm activity.

How looks LCD connector?
Any sign of liquid there?
External image present?
 

mccafe

Member
Very ugly.

I used an external hard drive with link LED (macOS Installer) and it shows no USB activity. Normally the light will stay on and fade in and out as it reads/writes data, but this one will flick on and then forever off quickly.

LCD connector looks clean - no corrosion or signs of liquid.

External image is not present. I get 0.4 - 0.5 amps on the amp meter, no power cycling. CPU temperature feels normally warm.
 

2informaticos

Administrator
Staff member
You could have bad CPU, or just a simple corroded resistor.
Is your choice to start check them, one by one.
High ohm resistor need to be measured out of board.
Also possible to have accumulated crap under CPU; try to heat it with good flux.
 
Last edited:

mccafe

Member
I was able to fix the issue by replacing R6110 (SPI ROM data line) 22 ohm and R1452 (PCIE_WAKE_L) 10K ohm

Thank you for your help!
 
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