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[SOLVED]820-4924 missing pp5v_s0

S

shlom

Member
Hello there friends...

working on a 820-4924 liquid damaged board
got it cleaned so no visible signs on corrosion..


measuring around the board, appears to be getting 1.04v on pp5v_s0
s3 and s5 are there reading 5.10v

looking at u8080 is getting the input on pin 3 from s3 (5.10v) but the en signal seems to be low (around 2.7v)
on R8187 i get 3.29v on 1 and 2.7v on pin 2..

checking this resistor which should be 47k ohm is reading around 17k ohm when it's in circuit
when pulling it out of circuit it's reading correctly 47k so i put it back on..

tried also replacing u8080 form a donor board, but still getting the same issue..

short to ground around this area maybe?
any help would be greatly appreciated...

thank you...
 
S

shlom

Member
measuring on the fan connector and also pin 1 on r1845 with the with multimeter on 2000k resistance mode i get 074 (black probe to the fan and the red to ground)...
 
S

shlom

Member
on L7520 i get pulsing between 5.08v - 5.11v
on L7560 3.32v on pin1 and pulsing on pin2 2.96-2.99

when i got it there was a little corrosion in the battery connector area
other than that it was pretty clean...
 
D

dukefawks

Administrator
It seems like P5VS0_EN is being pulled low. The only thing that can really cause this would be U8080 really. What is resistance to GND on this line?
 
S

shlom

Member
i can't read resistance to ground on P5VS0_EN, i think it's 0 (tried from pin 2 of u8080 and also from the c8187 pin) but didn't get resistance to ground..

is it worth trying to replacing the cap \ resistors on this line? i figure the EN signal will be created by those..
or try another u8080?

thank you sir...
 
S

shlom

Member
update:
i replaced u8080 again, seems like the one from the donor board was probably no good
like duke said - wasn't pulling the EN signal as it should..

i got the fan spinning and board is back to life!

SOLVED!
thanks to duke and JohnB...!
 
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