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820-3437- B Not turning on

KootenayMacGuy

KootenayMacGuy

Member
I have a water damaged 820-3437-B board that is not turning on.

Originally there was corrosion on Q7630 causing 200ma draw on power supply. I replaced this chip along with C7622 and C7624. There is now a 70ma being drawn and no power.

Green light on charger/turns to orange. I have verified this will charge a battery. I went through every single power rail and all tested good. What might be causing this 70ma draw?

S5/S4/S3/S0 all good both 3.3V and 5V
PPBUS_G3H is 8.59V
PP342_G3h is 3.42V
PPDCIN-G3H is 18.5V

Thanks is advance
 
KootenayMacGuy

KootenayMacGuy

Member
Just checked voltages:
L7130 = 8.61V
L7520 = 5.1V
L7560 = 3.3V
L7430 = 1.20V
L7630 = 0.367V (should be 1.05V ?) There is a .29ohm short to ground on this line. I connected power supply @ 1.05V, 1.5A and cannot find the short. Dead cpu maybe?
 
2informaticos

2informaticos

Administrator
Staff member
Do you mean 0.29 ohm, or 0.290 in diode mode?

Post U7600 voltages, pins 6, 12, 16, 17.
Check its solders and traces.
 
KootenayMacGuy

KootenayMacGuy

Member
PIN 6 - 1.80V
PIN 12 - 5.10V
PIN 16 - 3.30V
PIN 17 - 0.0V

And correction on short to ground. Its 40Ohm short to ground on L7630
 
2informaticos

2informaticos

Administrator
Staff member
That is no short at all.

Replace U7600 and check all surrounding components.
Pay atention to C7630 and R7630/31.
 
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