[SOLVED]820-2936 short to ground PPBUS_G3H

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aurel476

New member
logic board liquid damage short to ground on PPBUS_G3H,

I cleaned around smc and isl area (corrosion)

how can i find this short ?
 

dukefawks

Administrator
Inject voltage and see what heats up. There is a chance a high side FET is shorted so check all other rails first for shorts to GND before injecting voltage. Start low at 1V and monitor current draw.
 

aurel476

New member
i've not stabilized power supply for inject voltage,

i will check all other rails

if possible inject with battery 1,5v AAA ?
 

aurel476

New member
i ordered psu

I have checked all other rail no shorts, i

i cleaned motherboard with ultrasonic, now no short to ppbus_g3, now i have 4V, any idea ?
 

larossmann

Administrator
Staff member
What was corroded in the first place? What is the resistance between pins 17/18 and pins 27/28 of U7000? Is R7005 20 ohms?
 

aurel476

New member
17/18 3,2ohms 27/28 of U7000 20,4 ohms, R7005 20ohms (replaced because 265ohms)

Corroded in first smc area, backlight driver area with fuse backlight, next u7000 area
 

aurel476

New member
Solved bad R7025,

have you an explication why lowers ppbus_g3h at 4v

old value of r7025 is open line
 
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G.Beard

New member
Solved bad R7025,

have you an explication why lowers ppbus_g3h at 4v

old value of r7025 is open line
Read this data sheet and compare the typical application diagram to that of your schematic and board view. Then read the notes on pin out and operation.
Pages 4, 7, 8 ..... The package and pinout is not the same but I assume the label pins do the same job.

http://www.intersil.com/content/dam/...6/isl6269a.pdf
 
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