Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

[GfilipeZ]

This Logic Board suffered water damage.

PPBUS_G3H = 13,09V

When i started to check S5 power rails stage, i found that PP3V3_S5 was not stable.
So I started to check from the beginning, SMC_PM_G2_EN. I took off R8110; then R9160 and finally U7650. Then i realized that PM_EN_PVXS5 only starts to oscillate when enter in U7650.
I already tested with 2 different U7650, and with same result. So i suppose is ahead of U7650.

Checked all power rails from schematic page 100 and 101, and no shorts, no low resistance.

Any ideas?

[mon2]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

What is the voltage of

SMBUS_SMC_5_G3H_SCL ?

[GfilipeZ]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

Hi,

The voltage is 3,4V but not stable. Varies between 2,9V 3,1V 3,4V.

[mon2]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

Voltage of PP5V_S4 ?

SCL is a clock line so ok to fluctuate.

[GfilipeZ]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

Of course, SCL

PP5V_S4 = 0V

PP5V_S5 is oscillating, not stable.

[mon2]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

What is the voltage you are measuring @ PP5V_S5 ?

What is the voltage of P5VS5_EN (Pin #12, U7650)? Is it stable or oscillating ?

The PP5V_S5 rail is a LDO output from U7650 which may be defective.

Remove all power. Meter in resistance mode.

Check the resistance to ground of PP5V_S5 (C7651, pin #1).

[GfilipeZ]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

I'm measuring PP5V_S5 on C7651.

P5VS5_EN also oscillating.

I already tested with 2 different U7650, same thing.

C7651-1 = 497,2Kohm (edited)

[mon2]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

Confirm if SMC_PM_G2_EN is oscillating.

voltage of ALL_SYS_PWRGD ?

[GfilipeZ]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

"Confirm if SMC_PM_G2_EN is oscillating." Yes, it is. If i take of U7650 it stabilizes.

ALL_SYS_PWRGD = 0V

[mon2]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

ALL_SYS_PWRGD = 0V

So one or more of the voltage is not good and this line is pulled low to indicate this failed status.

Could be due to missing pull-up voltage PP3V3_S0 @ R7805 since you are not in this power state.

Remove all power, meter in resistance mode -> check the resistance to ground of this enable pin SMC_PM_G2_EN .

[GfilipeZ]

Re: Macbook Pro 13" A1706 820-00239 No power 20V 0A PP3V3_S5 not stable

Resistance is 100Kohm.