820-4924 - No Liquid Damage, No Boot, No Vcore

[nelo1012]

Hey guys,

I have this 820-4924, customer just brought it in saying it does not come on,

Absolutely no liquid damage anywhere, I triple inspected it with microscope, then Just for fun I ultrasonic cleaned it,

also reballed SMC, once that worked, still the same, no change,

PPBUS_G3H - Present - 12.59V
PP3V42_G3H - Present - 3.42V
PP5V_S5 - Present - 5V

PPVRTC_G3H - Present 3.42V​

PPBUS S5 HS COMPUTING - Present - 12.6V - Should be 8.6V - so im guessing is high

SMC_BC_ACOK - Present - 3.4V
SMC_PM_G2_EN - Present - 3.42V
SMC_ONOFF_L - Present - 3.42V​

PPVCC_S0_CPU - Not Present

PM_SLP_SUS_L - Not Present​

PM_BATLOW_L - Not Present​

PP3V3_S4 Not Present​

PP5V_S4 - Not Present​

PP3V3_S5 - Not Present​

PP5V S4 Not Present
PP5V S3 Not Present
PP5V S0 Not Present


Please HELP!

 

[2informaticos]

Any pulse at least at 5V_S4 rail?

 

[JohnB8812]

PP3v3_S5 is not present, so there is likely the problem. Check resistance to ground on that rail for a short. If it is ok, likely could be a bad TPS51980. If shorted, find the short!

 

[2informaticos]

Oops, I read too fast, didn't see that...

Post some voltages for U7501, pins 12, 13, 21, 22.