820-01598 No backlight

[bjf]

Any thoughts on where to start with a backlight issue on this board that had a very minimal spill? I can't find any sign of the spill or any physical damage on the board. There is video but no backlight. Works on external monitor. Keyboard, trackpad, everything else works fine. I tested it with my known-good 2019 test screen. No change. Not sure where to start with this.

 

[2informaticos]

Which schematic used for this?

 

[bjf]

I'm using the 820-01598 schematic. This had a tiny bit of corrosion to the right of L8410. Other than that, it was really clean.

 

[2informaticos]

I don't have this schematic

 

[bjf]

Is there a way to DM you?

 

[2informaticos]

Upload the schematic somewhere.
You can send link through PM...

 

[bjf]

I can't figure out how to do a pm with the new forum. I only see Start Conversation, which seems to be public

 

[bjf]

Send me a pm if you can and I'll respond

 

[2informaticos]

Is true, I don't see any option for PM.
Write to [email protected] directly.

 

[2informaticos]

Start checking diode mode to ground at both pins of D8410.
Also post its voltages.
Be sure F8400 is good.

EDP_BKLT_EN goes high?

 

[bjf]

Everything seems normal. F8400 is good. EDP_BKLT_EN is at 3.3V
D8410 measurements are good.
1) 1.116
2) .800

 

[2informaticos]

R8442 is good?
Do you get 0V at BKLT_SD?
Post voltage and diode mode to BKLT_SCL/SDA lines.
Be sure all R8450-53 are good.

 

[bjf]

Solved. You got me there with BKLT_SD. Blown trace right above R8402. Pin 2 had no connection. Working great now. Thanks for the help.

 

[2informaticos]

You're welcome, good job!