[SOLVED]820-3332 dead no light on charger

[shlom]

hello


working on a 820-3332-a logic board

looks very clean, no liquid damage, under the microscope couldn’t find anything that looks bad…

the board is dead, no light on the charger..


on F6905 i get around 16.73v on each side

ppbus_g3h is 3.295v

PP3V42_G3H is 3.393v


resistance to ground on ppbus_g3h showing 6.8 m ohms and dropping, on diode mode showing 0.422 v



on PP3V42_G3H showing 2.929 k ohms

seems to be ok, also the voltage on pp3v42_g3h but still no green or orange light on charger… (maybe bad dc in board? will try to get another one tomorrow to test with..)




i checked the one wire circuit

on u6900

pin 5 = 0.728v

pin 4 = 0.780v

pin 1 = 3.378v




a note :
u8900 seems like been worked on with remaining of flux, but i doubt it has anything to do with the issue of no power…



any advice on what to check next?


thanks…

 

[2informaticos]

Check voltages at pins 5 & 8 of U5110.
Post some voltages at U7000, pins 1, 2, 3, 19, 20, 9, 15, 27, 28.
Alsos check for short/low value at secondary supplies (big coils).

 

[shlom]

ok after some more measuring
r7021 and r7022 reading o.l and 37k ohms

bad resistors? need to go along with the isl or just those?

could make sense that this the problem?

btw, the reason for not having green light is probably because the dc in board.
couldn't get another dc in board but checked on another board and also no green light there..

thanks...

 

[2informaticos]

"pin 3 = 1.51v"
That is very bad; ACIN should jave aprox 4V.

Check R7010 and C7011, U7000 is the last option...