820-01958 5v only

[nik1981]

Hi, I have a liquid damaged 820-01958 that is stuck at 5v with 0a

PPBUS_G3H:12.21v
PPDCIN_G3H: 5.16v
PP5V_G3S: 0v
PP5V_S5_LDO:0v
PP3V3_G3H: 0.949v
PP3V3_G3H_RTC: 3.269v
PP1V8_G3S: 0v

Any help would be really appreciated

 

[nik1981]

0v on the coils around U7800

 

[nik1981]

C7910 Pin 1 - LDO_Core = 1.463v
C7905 Pin 1 - LDO0 - PP0v8_SLPS2R = 0.00v
C7906 Pin 1 - LDO1 - PP3v3_G3H = 0.00v
C7914 Pin 1 - LDO2 - PP1V2_AWAKE = 0.00v
C7911 Pin 1 - LDO3 - PMU_LD)3_OUT = 1.80v

 

[2informaticos]

Check R7900.
Also check diode mode to ground on the coils around U7800.

 

[nik1981]

Thank you for the reply 2informaticos.

R7900 is no stuff for me but pin 1 is at 0.610-0.620v

Coils diode mode:

L7806 = 0.007v
L7815 = 0.248v
L7814 = 0.248v
L7816 = 0.032v
L7817 = 0.032v
L7813 = 0.364v
L7819 = 0.448v
L7820 = 0.454v
L7822 = 0.440v
L7821 = 0.442v
L7823 = 0.362v
L7824 = 0.347v
L7810 = 0.207v
L7812 = 0.019v
L7811 = 0.019v
L7809 = 0.007v
L7808 = 0.007v
L7807 = 0.007v

 

[nik1981]

Maybe some crap under U7800 on the left side or under T2 chip?

 

[2informaticos]

Sorry, I was looking at wrong schematic (01598).

You may have bad U7800, or accumulated crap underneath.
Try heating with quality flux.

 

[nik1981]

Fluxed, heated and gave it a few little taps but no change unfortunately

 

[2informaticos]

Then you need to change U7800.

 

[nik1981]

With U7800 removed I'm still getting those low readings on diode mode. Could it be anything else before I order a U7800?

I expected it to alter the diode mode reading when removed

 

[2informaticos]

The diode mode readings on the coils are not caused by U7800, but T2.
You should compare the values with good board.