MacBook Air A2179 - shorted trackpad, PPBUS_G3H stuck at 1,1v.

[Gueric]

mon2 yup. exactly like what's on the ampmeter. 5.2v, stable.

[mon2]

Remove all power. Meter in resistance mode. What is the resistance across C7020?

[Gueric]

mon2 Same, 2,5 ohms.

[mon2]

What is the voltage to ground of CHGR_AUX_DET @ C7016 pad (part is not stuffed)?

What is the voltage @ PPCHGR_VDDA (C7075)? PPCHGR_VDDP (C7077)?

Test the replaced mosfets in resistance mode to be sure the replaced parts are not shorted.

Do you have a stable PP1V8_SLPS2R @ C7080? Needed to power U7000.

Then, suggest to reflow U7000 if the above check out ok.

[Gueric]

CHGR_AUX_DET : 1,3v
PPCHGR_VDDA : 5v
PPCHGR_VDDP : 5v
PP1V8_SLPS2R: 0v. I think that's the culprit. diode mode from C7080: 0.430 resistance mode is at least 300Kohms.

[mon2]

So this rail is created by U3200. Measure the resistance to ground first to see if there is a short on this rail or not. If not, then U3200 is defective or not soldered correctly.

[Gueric]

Will do some measurements tomorrow, it’s pretty late here. Thanks for you help so far

[Gueric]

mon2 So as the resistance on the 1,8v line was fine, I decided to replace U3200 and now It went from 0v flat to a few milivolts, unstable. sometimes 10mv, sometimes 50mv. Is this bad soldering/bad chip or could it be something else? maybe the other CD3217 has to be replaced aswell?

Also I reflowed the ISL just in case, but at that point I replaced it twice already so I'm definitely sure the chip is not at fault. Also diode readings have improved on PPBUS after the CD3217 replacement and this reflow, going from .530 to .500

[mon2]

https://logi.wiki/images/6/6a/820-01...iagram_LO2.pdf

[Gueric]

measured PMU_CLK32_SOC on a test pad. I'm getting 100mv.
PP1V8_SLPS2R: 20mv
PP1V8_AWAKE measures 0v.

[mon2]

My bad, U7800 is creating the PP1V8_SLPS2R rail.

https://repair.wiki/w/MacBook_Air_A2...VG3S_EN_repair

Check the details for:

Check output voltages of U7800

[Gueric]

Are you sure U7800 can output anything without PPBUS_G3H being fully present ? I’ll test all these voltages regardless.

[mon2]

Confirm the first 3 primary rails in the power up sequence. The ISL9240 is a buck-boost regulator. When a stable 5v is present, the part should boost to ~12v. When 20v is negotiated by the CD321x PD controllers, then the ISL9240 will enter buck mode and lower the 20v to ~13v to operate the logic board. As a power up default, each PD controller must be able to pass a stable ~5v onto the logic board else something is wrong here.

[Gueric]

mon2 the 2 CD3217 are outputting a stable 5,2v signal (PPDCIN_G3H) but the ISL is not boosting it. even with the 5,2v signal, PPBUS_G3H is still 1,1v, PP1V8_SLPS2R is 30mv, and PP3V3_G3H is completely absent of course. I know for sure the ISL chip itself is not the issue. replaced it twice and reflowed it once and problem was still the exact same.

Also there is absolutely ZERO current draw.

I also double checked R7021, R7022, R7061 and R7062 and they're all 1 ohm as expected. even with PP1V8 not being present, should I replace the ISL again?


At this point the only things I think might be defective would either be Q7030 or Q7040 (which I’ve replaced twice) or the ISL itself (replaced twice also), some internal damage caused by the trackpad short, or something else that we’ve missed.

[mon2]

What is the exact voltage to ground of PP3V3_G3H? The missing PP1V8_SLPS2R rail is created once PP3V3_G3H is present and stable. If this PP3V3_G3H is absent, measure the resistance to ground of this power rail.

[Gueric]

mon2 PP3V3_G3H is still absent because PPBUS_G3H is still at 1,1v. PPDCIN_G3H reads 5,2v like on the ampmeter but the ISL is still not functioning properly

the PPBUS_G3H issue is not solved yet

[mon2]

What is the voltage to ground of CHGR_AUX_DET @ C7016 (not stuffed) with the power adapter connected? Still @ ~1v3?

Also check:

CHGR_AMON
CHGR_BMON

[Gueric]

mon2. yes. C7016 to ground is 1,357v.

CHGR_BMON reads 0V, and CHGR_AMON is too hard to get to, it's only 1 tiny resistor hiding under the T2 metal shield. if you meant PPDCIN_G3H_CHGR_AMON, it reads 5,2v.

[Gueric]

The only 2 potentials culprit for this low PPBUS_G3H voltage are only Q7030, Q7040 and the ISL right? or did I miss something somewhere. one of those 3 chips being defective would also be unfortunate since I've already replaced them twice. maybe I've been unlucky.

[mon2]

Had to put up some curtains. Fun.

Confirm the details of the replaced mosfets. Note that there are 2 inside of each package. With no power, measure the mosfet pins:

source / drain
source / gate
gate / drain

For both, Q7030, Q7040. Be sure to test each permutation of each mosfet inside the single package.