A12179 820-01958 Missing EDP_BKLT_EN

[MobileXT]

I am working an a MBA 13 2020 that has no display. The MacBook power on but no display. After Checking on the backlight I found out that the EDP_BKL_EN was missing. And this power enable was coming from the PCH. So that means this MBA board is no chance to bring it back to life? any suggestion would really appreciate. Thanks, MobileXt

[mon2]

Re: A12179 820-01958 Missing EDP_BKLT_EN

Remove all power -> check the resistance to ground of EDP_BKLT_EN.

[MobileXT]

Re: A12179 820-01958 Missing EDP_BKLT_EN

Remove all power -> check the resistance to ground of EDP_BKLT_EN.

Diode Mode: .529v

Resistance to ground @ ohms
85.9kΩ

Thanks!
MobileXt

[mon2]

Re: A12179 820-01958 Missing EDP_BKLT_EN

Locate R0550 and measure the voltage on pin # 2. This is only to confirm that the trace for EDP_BKLT_EN is not broken from the PCH to the target.

Then remove all power, measure the resistance to ground of pin # 2 of R0550.

What is the reading ? Is it the same ~86K ? The resistor is a 100k value but perhaps while in circuit, the reading of 86k is normal.

[MobileXT]

Re: A12179 820-01958 Missing EDP_BKLT_EN

Locate R0550 and measure the voltage on pin # 2. This is only to confirm that the trace for EDP_BKLT_EN is not broken from the PCH to the target.

Then remove all power, measure the resistance to ground of pin # 2 of R0550.

What is the reading ? Is it the same ~86K ? The resistor is a 100k value but perhaps while in circuit, the reading of 86k is normal.

R0550 Resistance to ground @ 85.8kΩ
Diode Mode @ .528V
R0550 reading at 89.2K

[mon2]

Re: A12179 820-01958 Missing EDP_BKLT_EN

What is the measurement of the voltage on pin #2 of R0550?

Is it the same voltage as you are measuring at the enable signal rail?

[MobileXT]

Re: A12179 820-01958 Missing EDP_BKLT_EN

What is the measurement of the voltage on pin #2 of R0550?

Is it the same voltage as you are measuring at the enable signal rail?

R0550 PIN2 = 0v