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820-3462-A Green Light and Charges - No fan spin / power - Liquid Damaged

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Hellfiya

Member
Moderate liquid damage on board, above and under. R6920(47ohm resistor), Q5490(DCIN_S5_VSENSE) and ISL5269 were fried, replaced and got a green light. I thought these boards were supposed to be amber when no battery is present. Anyhow, if I attach a discharged battery then it turns amber and charges it. SMC reset also works. Any Ideas where to start? I can usually fix most boards but this model seems a lot more complicated or different than the others.

Also, I see that some of the caps around q7510 and q7550 area are corroded. Also, U5010.

Adapter sense fluctuates between 3.2v and 3.33v
DCIN 18v5 flucuates between 16.42v and 16.78v
PP3v42 at 3.39v
PPBUS_G3H very low at 1.1v

I've replaced ISL twice just in case and same result. I'm thinking the issue lies around U5010?
 
D

dukefawks

Administrator
PPBUS is needed first. 1.1V would almost suggest there is a short to GND, so check that first. Light should also go orange even without a battery, but that can be dealt with after PPBUS.
 
H

Hellfiya

Member
You're correct, something is pulling ppbus down to 500ohm resistance to ground. I'm going to look around the line until further instructions

EDIT: I have 12.3v on ppbus now and amber light without battery, it turned out to be a bad ISL6259 solder job or IC... still no fan spin or power

seems off: pm_slp_ s5_L is 3.3v, S4_L is .4v, S3_R_L,_L is 3.3v

PP5v_S4 is 5v, S3 missing, S0 is 5v

PP3V3_s3 1.4v, pp3v3_s0 is at 3v3

ppvccsa_s0_reg at .9v

cpu and pch gets warm,
 
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D

dukefawks

Administrator
12.3V would at least mean the ISL is not talking to the SMC, but that is a later concern but expect a dead SMC.

Is P5VS3_EN present? ALL_SYS_PWRGD present?
 
H

Hellfiya

Member
SMC did have quite a bit of corrosion on the test points surrounding it, I would not be surprised. I will check those two circuits when I get back to my workshop. Thanks Duke for your help
 
H

Hellfiya

Member
I'm getting 4.9v on pin 3(P5VS3_EN_L of q7852(SSM3K15FV), but not pin 1(No _L; 15ohm resistance to ground which seems short), which schematics show they should both be on. I tested and see the low resistance is on the PM_SLP_S4_L side. I forgot to mention U7940 has been replaced before, the PM_SUS_EN ic.

ALL_SYS_PWRGD is not present.
 
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