820-2936 PLT_RESET_L 0v

[MUUK]

820-2936

Old liquid spill
Green light, fan spins no display, no chime, usb lights up

R2805 area has hole.
Replaced R2805. replaced U2800 & y2805
Ran wires to connect broken traces.
Still does the same. Boo!


Check power rails
PP1V8_S0 1,792
PP1V5_S3 1.499
PP1V5_S3RS0 1.499
PP1V5_S0 1.503
PPVTTDDR_S3 0.752

PP0V75_S0_DDRVTT 0v Ah ha

Diode mode to ground on PP0V75_S0_DDRVTT 0.213v on donor 0.318 (significant ?)

U7300

pin1 0v
pin2 1.5v
pin3 0v
pin4 0v gnd
pin5 0.752
pin6 1.797
pin7 0v
pin8 1.495
pin 9 1.5
pin 11 1.9v
pin12 5v
pin13 1.5v
pin14 1.5v
pin15 6.4v (?)
pin16 3.2v
pin17 0v
pin18 0.9v
pin19 0.03v
pin20 4.2v (odd ?)


R3210
pin1 PM_SLP_S3_L = 3.2v
pin2 MEMVTT_EN= 0v
MEM_RESET_L high


So i'm missing MEMVTT_EN which should come from PM_SLP_S3_L

PM_SLP_S3_L is high at pin 1 of R3210 but 0v on the other side.
diode mode to ground on both side matches donor board (0.318 and 0.418v to gnd)

Replaced R3210 even though measured fine, no change.
Replaced Q3250 no change

Q3210

pin1 gnd
pin2 4.9v
pin3 4.9v
pin4 gnd
pin5 0v
pin6 0v

so PLT_RESET_L is low when should be high.
PLT_RESET_L seems to come from the CPU/PCH - is this the end for this board ?

 

[dukefawks]

PLT_RESET being low could have many causes. Corrosion under SMC/PCH, clock chip problems. It could be internal board damage if there really was a charred hole at R2805 position.