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BMCappelletti · 04-25-2026, 05:49 PM

Well, I guess that should be 2.2 ohms resistor.
I measured the side with no voltage on diode mode and the resistance is extremely low, almost zero. So I guess the RT chip is also fried and both need to be replaced.
Any input is still welcome. Thanx.

BMCappelletti · 04-25-2026, 04:22 PM

BTW, the resistor is measuring 11.8 ohms, in circuit.

BMCappelletti · 01-26-2026, 08:42 PM

Well, it took me some time to try again, cause I got a new job and didn´t have much time for it.
I replaced U5200 and on the very first try got 20V on the meter. Set it aside as it was dinner time.
Came bak, connected the meter and power again... back to 5V. Q5230 is glowing hot. I lifted L5230 and the short comes from CHGR_PHASE1. So still issues with the ISL chip? Why did it show 20V and the next try went to 5V again?

BMCappelletti · 01-13-2026, 09:24 AM

I don't think this board requires a connected battery to negotiate 20V. At least I don't remember connecting one to it when I first solve the original issue. And I have repaired two or three M1s before and also think I never had to connect it....

BMCappelletti · 01-12-2026, 09:30 PM

Welll, made some progress.
Replaced U5340 with one from a donor board. Now the short on PPCHGR_VDDA is gone.
Still 5V on the meter, though.
But also 5V on U5340 pin 5 and 1V on the F5200.
Back to previous step. 5V and no current drawn, at all. Will replace the ISL again. Have one extra.

BMCappelletti · 01-12-2026, 09:56 AM

Did that. No luck.
So, removed the ISL chip. Still a 3.4 ohm short on C5275 PPCHGR_VDDA.
PPCHGR_VDDA goes to (among other places) R5275. That resistor is measuring fine, at 4.7 ohms. The cap above, which is C5277, is also fine.
So maybe my option is to check U5340. I do have 1.3V on the enable pin, but nothing on pin 4, which is PPCHGR_VDDA. Does this make sense?...

BMCappelletti · 01-11-2026, 08:05 PM

Short comes from pin2 (CHGR_PHASE2) connected to mosfet Q5240.
I removed Q5240 and short is still there.

Seems like this line comes from C5240, connected to C5275 and the ISL chip I replaced....

BMCappelletti · 01-11-2026, 01:11 PM

A full short. 0.1 ohms....

BMCappelletti · 01-10-2026, 09:28 PM

Well... it took a long time for the new ISL chip to get here, due to a post office strike.
Anyway, I installed it and... no luck. Still not negotiating 20V. But I noticed L5230, on the side of the board, is shorted. A full short.
Those are CHGR_PHASE1 and 2, and it comes from the mosfets beside it.
I guess it can come from a not well installed ISL chip, even though I think it is correct installed.

BMCappelletti · 12-13-2025, 11:37 AM

Yep. Will try to do it without the need for reballing. Let's see how it goes. If a reballing is needed I still have some 0.35 (I think) ones that I used on a PS4 south bridge. Also have some paste.
At least it does not seem to have the undefill, that the Macbook Pro 2018 has on the CD3215 chips. I posted about it some time ago and I believe I need to replace that.
There is a first time for everything.
Thank you!...

BMCappelletti · 12-13-2025, 10:55 AM

Nevermind. They are inverted. It is 1.2V on both.
R5215 pin 1 is 5.1V....

BMCappelletti · 12-13-2025, 10:37 AM

1.2V on R5215 pin 2. But 0V on R5216 pin 2.
Resistance on those is around 200 k ohms....

BMCappelletti · 12-13-2025, 10:16 AM

0V on this resistor....

BMCappelletti · 12-13-2025, 09:21 AM

4.8 ohms, across....

BMCappelletti · 12-13-2025, 09:11 AM

0V.
I do have the 5V on R5221, that the meter shows....

BMCappelletti · 12-13-2025, 09:05 AM

No, I do not.
Still 5V on the meter and no amps drawn....

BMCappelletti · 12-13-2025, 08:52 AM

C5260 is indeed 2 ohms. Changed my probes for new sharped ones. Probably got a better connection....

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