820-01987 20v and seems to be booting but no display/keyboard

[SoloHarty]

Hi,

Got a liquid damaged A2289 in and found heavy corrosion around U7100, U4900 and U4920. Cleaned and replaced all corroded components and found a hard short on U7270. Replaced and we get fan spin, CPU warming up and trackpad clicking but that seems to be it.

For voltages around CPU:

L8100 - 1.204V
L8102 - 0.967V
L7270 - 0.00V
L7210 - 0.00V
L7220 - 0.00V

U7270 still gets warm when nothing else does. like 46-47*C

U7270 Voltages:

pin1 - 0.043V
pin2 - 5.069v
pin3 - 0.00v
pin4 - 3.268V
pin5 - 12.61V
pin6 - 12.61V
pin7 - GND
pin8 - 0.00V
pin9 - 0.02V
pin10 - GND
pin11 - 5.106V
pin12 - 1.628V
pin13 - GND


could CPUSA_DRVH being missing cause anything like this or could the CPU just be braindead?

 

[2informaticos]

L7270 voltage should appear before L7210/20.
Compare diode mode readings with good board.

If you got short on U7270, CPU is probably dead; overvoltage through U/L7270.