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820-3115 quarter fan spins in loop

Bouba148

Bouba148

New member
BOARD HAD LIQUID DAMAGE AROUND TE EDGE OF THE BOARD (SMC AREA)

PPBUS_G3H : 16,11
PP3V42_G3H :3,476
PPVRTC_G3H :3,317

5V Rails:

PP5V_S5 (PP5V_S5_LDO) : 5,030
PP5V_SUS : 5,030
PP5V_S3 :0V TURNS TO 5V WHEN FAN SPINS
P5V_3V3_SUS_EN : 3,316v
SMC_BATLOW_L : 3,284V
PM_SLP_SUS_L : 3,315v
SMC_RESET_L : 3,444V

3.3V Rails:

PP3V3_S5 :3,297V BUT QUICKLY DROPS TO 1,4V WITH THE QUARTER FAN SPIN
PP3V3_S4 :0v BUT TURNS ON WITH THE QUARTER FAN SPIN

U7200 VOLTAGES:

P5VS3_ENTRIP: 0V
5V3V3_REG_EN: 3,431V
P5V3V3_REG_EN: 3,461V
P3V3S5_ENTRIP: 0,769V


PPVRTC_G3_OUT: 3,316V
SYSCLK_CLK32K_RTC : 32,77KHZ
CPU_VCORE_SO_CPU: 0v JUMPS TO 0,300v WHEN FAN QUARTER FAN SPINS resistance to ground 4ohms,I'm wondering if its not a short to ground?
ALL_SYS_PWRGD: PULSING TO 3,3V
voltage on R5014 IS 3.4V BUT PULSE TO 0V WHEN FAN SPINS
PP5V_S0 :0V BUT PULSE TO 4,5V WHEN FAN SPINS
 
Bouba148

Bouba148

New member
Thanks John for your reply. Do you think that if i don't replace everything at the same time there is a risk to blow again ? What if i replace the isl first for example . .
 
D

dukefawks

Administrator
See if it wants to power from a charged battery. The ISL circuit is not needed for that. If it also does quarter fan spin on battery then there are more issues.
 
S

SMMRepair

Member
Also keep in mind that if liquid hit that SPI ROM chip, it could be damaged...and symptoms would be very similar to what you describe. Swap over another chip (just for testing!) once you address the obviously damaged stuff.
 
Bouba148

Bouba148

New member
Hi JohnB8812, Dukefawks, team

it was the 4th possibility: both traces from resistors R7051 and 7052 to R7050 were blown. I've put new traces.
Now fan spins fine at power ON and have a nice 12,71v for PPBUS_G3H but the ISL is getting very hot (can't let my finger on it more than 3-5 sec) so i'm disconnecting the charger to prevent something else to blow.
Do you think this new ISL has been damaged because i've put the power on the board before solving the traces/high resistance issue?
 
Last edited:
J

JohnB8812

New member
Possibly bad soldering or a bad ISL. 12.71 volts is a little high so if a new ISL doesn't bring it down, that makes Q7080, Q7030 and Q7055 suspect
 
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