820-3437 - No power, green/orange light ok.

[gcain]

Had a liquid spill exactly on C7500 and C7503.

Since C7500 is 8v and C7503 is 5v, is it fair to guess a dead U7501?

 

[Paul Daniels]

Also check clock / ROM area ( U6100, Y1905, U1900 ), very common for 3437/00165 to suffer issues there due to liquid ingress (or even just literal bugs), especially if it got as far in on the board as C7500.

 

[dukefawks]

You are guessing without taking any measurements?

 

[gcain]

You are guessing without taking any measurements?

PPBus = 8.57v
PP5v_s5 = 1.045v
pp3v3_S5 = 0v
PP3v42_G3H = 3.42v

Investigating 3v3_s5 first.


-- side note for later.
S5_PWRGD @
R1841::1 = 3.42v
R1841::2 = 0v

 

[gcain]

U8020 isn't getting P3V3SUS_EN

 

[gcain]

P5Vp3v3_VREF2 = 1.46v

 

[dukefawks]

There is no 3v3_s5 why are we looking at U8020? This is something around the TPS51980 or a short on 3v3_s5.

Check traces around U7501 and/or replace.

 

[gcain]

There is no 3v3_s5 why are we looking at U8020?

Not specifically U8020, but 3v3SUS_EN.

This is something around the TPS51980 or a short on 3v3_s5.

Check traces around U7501 and/or replace.

The traces around U7501 are horrible but seem to beep out ok.

 

[dukefawks]

Replace 7501 and check traces while it's off, especially pin 23.

 

[gcain]

::23 has continuity to C7540 et al, but ::24 has nothing to Q7560.

 

[gcain]

Got continuity back. Replaced u7501 with a new one.

PP5v_S5 @C7505 is 0.9v now. Crappy soldering maybe?

 

[dukefawks]

I have no idea, you have your eyes on it. This problem is around U7501 for sure.