SOLVED: 820-4924-A P5VS0_EN/PM_SLP_S5_L pulsing

[it-solve]

A1502 board with quite of heavy corrosion on this area

PP3V42_G3H 3.4V3
PP5VS0_FET- 0 -2.3V pulsing
P5VS0_EN- 0 -1.6V pulsing
CHRG_VREFQ - 3.33V - 0V pulsing

PP3V3_S0 - 0.08V

u7100
PP5V1_CHRG_VDD - 5.12V
PP3V42_G3H_CHGR - 3.43V
PPBUS_G3H - 12.56 - 12.33V power cycles

SMC_ADAPTER_EN - 3.40V
SMC_PM_G2_ENABLE - 3.42V

PM_SLP_S5_L - 0 - 1.2V pulsing

Also, although the board is 820-4924-A 820-4924-A/820-3476-A board view doesn't seem to match exactly to the board. For example, U6100 is not on the top corner. Does anyone have the matching board view for 820-4924-A?

 

[2informaticos]

The 4924 boardview I have, has the SPI chip placed in the center of the top side.
I didn't see any other boardview for 4924...

Does your board turn on in SMC bypass mode?

 

[it-solve]

It doesn't. When left on the side for a while and I apply the charger it pulls 0.26A for a couple sec and drops back to 0.01A

 

[2informaticos]

Do you get pulse at all big coils?
Check for short on coils and secondary power rails; Misc Power supplies and Power FETs pages.

Also check for pulse at pins 7 & 3 of U1950.

 

[it-solve]

Found the issue, thank you for your time.


Initially, I was looking at these coils which had No Short on big coils or big caps
Pulse on L7520, L7430, L7310/20, L7630

Non-pulsing coils
L7560 - 3.3V
L7130 - 12.5V

When I measured pin 7 on U1950 it starts pulling 0.17A. Seems like the internal resistance of the multimeter spun it up.
I could feel the CPU was getting slightly warm, but no USB activity (only blinks ones) nor any screen. Also no more pulsing coils.

Voltages on the big coils seem fine.

U1950
Pin 7 - 0.26V
Pin 3 - 0.3 -0.18V discharging

Then I decided to lift up U1950, and as I thought it had corroded pin 9 PPV3V42-G3H, which must be the reason for pulsing voltages as it doesn't get stable voltage.


Thanks for your assistance.