820-01987 No Backlight

I have a computer that came in water damaged, powers on with no backlight. Corroded area was around C8560, rest of the board is clean. R8452 was missing w/ no pads & U8472 Hole in it. We jumped R8452 to R8453 & R8450. During the replacement of U8472, R8455 & R8481 may have been blown off. I could only find one resistor. Schematic does not say no stuff for either. Does anyone have a picture of that area of the board or does anyone know if both need to be on the board.


Staff member
"We jumped R8452 to R8453 & R8450."
Consult schematic, there is no contact between R8450/53.
Rebuild the traces based on schematic.
All R8450-53 must be present.

U8472 burnt with hole in, T2 could be damaged now.

Replace all damaged components and be sure to get good traces.
i checked the traces from the board and double checked with the schematic. can you help me understand because i checked it and i thought it was connected.

Topside of r8452 is connected to pp5v_g3s which is also connected to r8453
bottom side of r8452 is connected to I2C_BKLT_SCL which is connected to r8450

if you could explain where i went wrong i would appreciate it!


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Staff member
"We jumped R8452 to R8453 & R8450"
This sounds like you've put all 3 resistors in contact; there is no common point.

If you did it as explained in last post, is OK.
okay, i put back R8455 and R8481 but i still don't have backlight. can you help me rule everything else out before i have to replace t2? the board is booting up and everything else is working exepct backlight. wouldn't this mean t2 is sill good?


Staff member
T2 works, but nobody can assure its backlight adjust output is still good; hope it is.

Did you replace all, including U8472?
Post its voltages.
Do you get EDP_BKLT_EN?