820-00850 (A1989) - PPBUS_G3H looping


PPBUS_G3H is looping between 12.25 and 12.57V on an A1989 (820-00850).

Also the output of the USB-C ports are weird.
- 19.4V
- 0.00-0.04A
I assume the CD3215s are fine because I get 20V, right?

What should I check next?
I have checked the SLPS2R + AWAKE (all present).

PP1V2_AWAKE = 1.2V
PP1V8_AWAKE = 1.8V
PP3V3_AWAKE = 3.3V

PP0V8_SLPS2R = 0.8V
PP1V1_SLPS2R = 1.1V
PP1V8_SLPS2R = 1.8V

PPBUS_G3H = 12.57V (should be fine)
USB-C Output = 19.4V / 0.04A (DFU Mode - Since when is 0.04A DFU Mode? I thought 0.07A is DFU mode?!)

i have also tried via FORCE_DFU + PP1V8_SLPS2R (usb c output 19.4V / 0.08A)

In DFU mode PPBUS_G3H isn't pulsing / looping.
Note: I can't restore the device via AC2 error message:

"Gave up waiting for device to transition from DFU state to DFU state. [com.apple.MobileDevice.MobileRestore - 0xFCA (4042)]"

Please don't tell me that the T2 is bad. :(
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I have accidentally shorted C7080 (PIN1 = PP1V8_SLPS2R) and C7021 (PIN1 = CHGR_CSI_P) with my multimeter tip .....
No short on PP1V8_SLPS2R or CHGR_CSI_P but now I only get 5.02V and 0.05A on all four USB-C ports ....
Comparing the PP1V8_SLPS2R diode value to a good known board is the same (0.412).

But why the hell im getting now 5.02V and 0.05A (sending outwards to the charger) on the USB-C port?
PPBUS_G3H = 0.9-1.1V (did I broke my ISL?)
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Staff member
"Comparing the PP1V8_SLPS2R diode value to a good known board is the same (0.412)."
Did the same for PPBUS_G3H?

Nothing will wotk, if no PPBUS_G3H present.
So I have replaced the ISL .... im now getting 12.57V (PPBUS_G3H) again. (so yeah I fucked with that short my ISL - was kinda stupid :D)

But here we go...

PP1V8_G3S = 1.8V
PP3V3_G3S = 3.3V

I2C_SSD_SCL = 0.7V
I2C_SSD_SDA = 1.8V

- Trackpad is clicking
- In DFU mode PPBUS_G3H is 12.25V is that normal?
- While restoring BridgeOS it is looping between 12.25 and 12.57V, any idea?

Here a video of the usb c output:

Diode mode value from PPBUS_G3H (working board) = 0.412
Im getting 0.372 .... can be ignored?
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Staff member
In DFU mode, T2 firmware is supposed to be reflashed; it can't control ISL9240 all this time.

Even no short to ground present at 1V8_SLPS2R, this doesn't discard a damage on some chip powered from this power rail.
What else should I check?

Edit: I mean it’s the same behavior in the AC2 before and after the short (made by me).
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that sucks … already the third MacBook with a T2 or SSD issue.

Edit: Is it normal that in DFU mode that the usb c output goes up to 20V?

Edit2: The battery is also not charging correctly which means the current goes up to "0.15A, 0.35A, 0.55A and 0.70A" and than it gets reseted to 0.00A. (starts again)
Could be a faulty CD my issue?
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I have tested it again restoring BridgeOS while the logicboard is in the housing …. All four ports are doing when the battery is connected …

Note: Issue only occurs when the battery is connected.

- With battery ... PPBUS = 11V (stable) - USB-C output issue
- Without ... 12.57V (not stable) - USB-C output no issue
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Values = diode mode
L7220 = 0.004-5
L7210 = 0.004-5
L7410 = 0.004-5
L7420 = 0.004-5
L7430 = 0.004-5
L7270 = 0.022
L8102 = 0.120
L7702 = 0.110
L8100 = 0.200
LB700 = 0.495
L7600 = 0.390
L7660 = 0.410
L7030 = 0.495
L8410 = 0.850
L3500 = 0.380

L7220, L7210, L7410, L7420, L7430 .. I assume they are low because they are on the CPU side, right?
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I assume you mean "L7660" and "L7600".

L7660 (PP3V3_G3H) = 3.3V (stable)
L7600 (PP5V_G3S) = 1.3 - 5.1V (not stable)

P5VG3S_EN is also pulsing (0-3.3V) .. so thats possible the reason why PP5V_G3S isnt stable.
Source of P5VG3S_EN is U7800? (Bad U7800?)
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