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820-00923 no power

M

Max7

Member
This one came as not turning on. The board is clean, with no signs of corrosion.

The power draw is steady at 5v 30mA. Although this is quite similar to Louis' TB Rom video I don't suspect that since the behaviour is steady on all four ports.

PPDCIN_G3H = 5v
PPBUS_G3H = 0v - not shorted
PP3V3_G3H = 0v - not shorted

D6902 is fine and providing 5V
PM_EN_P3V3_G3H is missing.

I need a bit of help on what to check next. Many thanks.
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Check PPBUS_G3H and 3V3_G3H voltage with both charger and battery connected.

Post U7000 basic voltages: P_IN, AUX_DET, SMC_RST_IN, VDDA/P, EN_VR1, SMC_RST*, AUX_OK, A/BMON.
Remove F7000 and check C7050 voltage.

Check SMC_USB_INT_L level.
 
M

Max7

Member
P_IN = 5.2V
AUX_DET = 1.27V
SMC_RST* = 0.545V ??
VDDP = 5.02V
VDDA = 5.07V
EN_VR1 = 5.08V
SMC_RST_IN = 3.3mV ??
AUX_OK = 0.546V
AMON=0.468V
BMON=0.450V

When I touch the red probe to BMON to measure voltage, the power draw goes up to 20.1V / 0.0A and stays there.

PPBUS_G3H and 3V3_G3H stayed 0 with or without the battery connected. Above voltages with no battery.

Many thanks
 
M

Max7

Member
C7023 = <2.3 ohm, normal isn't it given that R7020 is very low resistance ?
C7020 = 5.3 Mohm

U6903 voltages
BST = 7.76V -> P3V3G3H_VBST
SUP = 4.78V -> PPVIN_G3H_P3V3G3H
LX = 3.43V
BIAS = 4.76V
FB = When I measure it it is 1V, then if I keep the multimeter, power draw goes up to 20.1V (0.0A) and FB pin goes down to 50mA or so.
EN - 5.08V

D6902
output: 4.78V
PPBUS_G3H_R: 3.8V
PPDCIN_G3H_CHGR_R: 5.09V

PPBUS_G3H: 3.8V
PP3V3_G3H: 3.34V
sorry these two conflicts with the previous 0V measurement :( I have replaced ISL after the first post. Not sure if that made a change.
Normal power draw also went up to 40-50mA from 30mA (all 5V)
 
Last edited:
M

Max7

Member
R7962 is 1 ohm as expected
R7961 is measuring 44 ohms even after removing it from the circuit.

Replaced R7961 with a good resistor. Now power draw starts with 5V and switches to 20.1V, 0.0A.

I will measure voltages further tomorrow, please let me know if this resembles a typical issue.

Thanks a lot for the help
 
2informaticos

2informaticos

Administrator
Staff member
No need to put board back yet.
You can check if CPU core comes on with correct voltage.
It should drop to 0.65V after 10-15s.
 
M

Max7

Member
Just to conclude the thread, after fixing the resistor above, the ISL was overheating, perhaps a faulty one (after the replacement). I had to replace it again, everything started working as expected.

Thanks a lot for the help.
 
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