820-00165 Partially In S0, Low PP5V_S4S3

brunomotter

Member
Hello. Got this board here with a strange issue. It partially turns on(some S0 state voltages are present). No fan spin. I have DDR voltage stable ate 1.2V, but PP5V_S4 is measuring low, at only 3.05V. Tried replacing TPS51980 and MOSFET, still same. Something is dragging 5V voltage down, some kind of leakage, but nothing gets warm. Board had no corrosion at all, everything looks pristine. Any tips on how to solve this?
 

2informaticos

Administrator
Staff member
Diode mode to ground at L7520?

Check R7520/21/23 and their traces.
Pin 4/U7501 goes high?

BTW, you can't get any S0 voltage without 5V at L7520...
 

brunomotter

Member
Diode mode to ground at L7520?

Check R7520/21/23 and their traces.
Pin 4/U7501 goes high?

BTW, you can't get any S0 voltage without 5V at L7520...
I also thought it was not possible to get any S0 voltages without stable 5V on L7520, but that's exactly what's happening. I have 3.05V there and still get stable 1.2V on L7430. Diode mode reading on L7520 is 0.398. R7520/21/23 reading fine and traces ok. Pin 4 of U7501 stable 3.3V
 

2informaticos

Administrator
Staff member
Don't get confused; 1V2_S3 is not in S0 state.
Pay atention to schematic, U7400 is powered from 5V_S5.

Check all U7501 components related with 5V output.
Pay atention to R7545 and C7524.

Please, don't quote an entire post, visible few centimeters above...
 

brunomotter

Member
R7545 is fine. Replaced C7524 just in case, same thing. PP5V_S5 is stable @5V. I tried lifting every cap related to 5V output that point to GND, but same 3V on PP5V_S4RS3 output but same. Certainly something has leaking voltage on 5V line, but cannot find what it is.
 

brunomotter

Member
Sorry, don't have thermal camera here. But the only thing that gets a little warmer than the rest of the board is the webcam controller region, which is fed by 1.2V and not PP5V. And that's after around 5 to 10 minutes connected to charger.
 
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