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forkus · 04-08-2026, 08:54 AM

Just closing the loop on this A1706 case.

Isolated the rail at L8000
- VR side: normal resistance (kΩ range)
- CPU side: hard short to ground
Freeze spray test: surrounding caps show nothing, but one corner of the CPU die defrosts first
Injected 0.9V into the rail with 1.5A current limit → current immediately maxes out

Conclusion: confirmed short on the CPU (PP1V0_SUS rail). RIP.

Special thanks to mon2 for the help — much appreciated...

forkus · 04-07-2026, 12:28 PM

Sorry one more question: U7800 can be the issue? I've checked inputs PM_SLP_SUS_L and PP3V3_S5 both are OK but P1V8SUS_PGOOD == 0 and PP1V8_SUS = 0V? Or the U7800 is just part of the cascade failure?...

forkus · 04-07-2026, 10:25 AM

PP1V0_SUS = 0.001 oHms (192 oHms on known to be working board)
PP1V0_SUSSW = 0.001 oHms (173 oHms on known to be working board)

Will try to inject power. Thanks!

forkus · 04-07-2026, 09:41 AM

PP1V0_SUS short
PP1V0_SUSSW short
PP1V0_S3 = 347 oHms
PP1V0_S0SW = 362 oHms

RIP PCH?...

forkus · 04-07-2026, 09:27 AM

PP5V_S0 = OL (open, no short to ground).
In diode mode = 0.445...

forkus · 04-07-2026, 09:17 AM

PP1V8_SUS seems to be short on ground. How to localize the source?

forkus · 03-29-2026, 09:26 AM

and R6001 same feeling, but maybe it's quality of the photo.

forkus · 03-28-2026, 05:41 AM

Nevermind. It's flexgate issue again.

forkus · 03-27-2026, 09:41 AM

Check the components on the reverse side of the board near the keyboard connector. In most cases (except for a loosely secured trackpad connector), when placing the motherboard into the chassis, the keyboard ribbon cable gets trapped underneath the board, and when prying it out, some SMD components may get knocked off.

And yes, it's absolutely not a fan issue.

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Macbook A1706 doesn't start - 20V 40mA current

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MacBook Pro 16" A2485 M1 Max (2021): No internal display - external works fine