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

[Gueric]

Before I do the measurements, I have to ask you about the markings on those mosfets because I’m very confused. If I remember correctly the 2 original ones that were dead had « Z340 øCP △T96K » written on them. I pulled the 2 same mosfets as replacement from another A2179 board but the markings were completely different (it says on it : T30 2024), and what’s even weirder is that those mosfets on the schematics are named SIZ342DT. Do you have any explanation? This is very confusing. Maybe you could send me a link to the exact model of those mosfets I could buy and replace them once for all? Because maybe that’s the actual issue.

thanks

[mon2]

https://www.vishay.com/docs/62949/siz342dt.pdf

https://www.digikey.ca/en/products/d...T1-GE3/6595020

https://www.aliexpress.com/w/wholesa....home.search.0

[Gueric]

thank you very much. I will order some SiZ342DT-T1-GE3 Mosfets, replace them both and give an update here.

[Gueric]

Hey mon2 ! I'm back.
So after replacing the 2 ISL mosfets, PPBUS is now fully back at 12.3. The issue is, board only draws 5,2v. When plugging the charger, small spike to 170mA for a fews seconds, then 70mA, and remains at that level, no matter how much time passes. Both USBC ports show the exact same readings. I tested some voltages, and 2 were no present at all, PMU_CLK32K_SOC and P5V3GS_EN.


Otherwise every other line is present. I measured voltage readings that were lower than expected on those 2 lines (1st and 2nd picture) I basically got what OBData says is DFU mode voltage. The weird thing is nobody has put the laptop in DFU mode.

is the T2's firmware just corrupt so do I try to put it back in its housing and to the keyboard combo, or is it dead, or is the PMU dead? Thanks

[mon2]

You are missing PMU_CLK32K_SOC? This clock is required. Review crystal @ Y8001 which is the base clock used by the PMU.

[Gueric]

Ok my bad mon2 there were 2 test pads very close to each other and I was measuring the wrong one. PMU_CLK32K_SOC is 860mv as expected.

I was making some measurements and realized PCH_RTC_RESET_L is 3v. from there, P5VG3S_EN is 0v, PP5V_G3S is around 50 to 100mv, and everything after is completely missing (P3V3G3S_EN, PP3V3_G3S etc) I attached the power sequence PDF is was following when measuring.

[mon2]

Remove all power. Meter in DIODE mode. Red meter probe to ground. Black meter probe onto R7613. Test each side of this resistor to be sure it is reaching U7610 input pin #1.

What is the measurement? We are checking if this missing signal line is floating due to a broken trace or just not being driven by the PMU.

[Gueric]

mon2 each side of the resistor measure exactly the same, 0.634v

[mon2]

Try a DFU.

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

[Gueric]

mon2 thanks, will try that. Quick question tho. Since the board only draws around 80mA will the keyboard combo work at all?

[mon2]

TBD. In theory, only a small segment of the board needs to be powered to restore the assumed and corrupt firmware. That is the premise. Once the firmware is restored by this process, only then will the board power up to full potential and then consume much higher currents. Curious to learn if this works for you - I think I am in a similar position.

If in a pinch, I think I may have the T2 dump for this unit but need to confirm it. That is, you can then hot air off the flash device used by the T2 directly and reflash it without the DFU process. Try the front door method first and we can explore this alternate idea if needed. Be sure to follow the many YT articles and use quality USB cables, etc.

[Gueric]

mon2 interesting thanks man. Just realized that the trackpad connector and the keyboard connector seem to be the same, so I will have to wait for the replacement TPAD connector to arrive, replace it and try the combo. will update here maybe this weekend.

[mon2]

If this is an ongoing interest to service these devices then suggest to invest into the kinky footprint sockets and PCBs to mate with the 8 pin SOIC programmer. Highly recommended. I would even pull the trigger today from Aliexpress.

Review the T2 flash device which are 2x3 or 4x3 - order support materials for both footprints.

https://www.aliexpress.com/item/1005...675918024jRs92

This vendor has affordable zero force sockets for both.

Also suggest to order the 'purple' board:

https://www.aliexpress.com/item/1005...75551802R6X1hR
* has support for soldering down the 2x3 or 4x3 USON8 packages

Finally - order a few of the exact flash device(s) used on these boards. Perhaps none of the above will be immediately required if the DFU works as expected but are a good fall back plan.

Here in Canada - they are all rare as the dodo bird.