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I replaced U2800 and UB000 and the situation is unchanged.

Since all 4 ports are nonfunctional, are both U2800 and UB000 likely defective?

This 820-01700 board arrived with a single misbehaving USB-C port. I found a shorted CD3215, which I replaced with a location-matched chip from a donor board. Now all 4 ports charge the battery and power external USB drives but don’t allow for any data transfer. External drives are recognized...

Ah, yes. This is also why DFU Revive/Restore fails without a functioning SSD, correct?

This 820-01700 board arrived stuck at 5V USB-C. I found a short on the SSD0 NAND chips: it shows 3Ω to ground on L9530 (P1V8_SSD0) and 2Ω on L9580/1 (P2V5_SSD0). When I temporarily remove L9530 and L9580/1, I get 20V on USB-C (0.03A) and PPBUS is 12.6V. But no chime or startup. Before I...

Got it. So when I see a diode mode reading, for example, on PP0V82_SLPDDR that's half of the value of a good board, it implies that the T2 is drawing too much current?

Some diode mode readings are lower than on a good board but I see no shorts to ground. What causes U7800 to pulse?

This non-damaged 820-01700 board is stuck at 5.2V 0.04A on all 4 USB-C ports. I have PP3V3_G3H_RTC_X and all 3.3V and 1.5V LDOs. PPBUS is 12.3V. PP1V8_SLPS2R and PP1V1_SLPS2R are missing but pulse every second without stabilizing. Does this point to an issue with the PMIC U7800? How to best...

Aha. Just learned something I did not know. When FileVault (Disc encryption) is on, the Touch Bar remains completely dark until after the password is entered. Same for Diagnostics and Guest Mode. I verified this using an identical machine set to my account. So your hint was spot-on: get the...

Inspection showed absolutely nothing. No touch function, no illumination.

This 2020 M1 machine came to me for battery replacement. Works fine now except I can't get the Touch Bar to turn on. The Touch Bar works fine with another logic board in the same topcase. I don't have the customer's password, but the Touch Bar should illuminate on the login screen, correct...

Good to know about the A1990… thanks. I did find an old A1708 display and plugged in its camera flex cable to the T-CON board. I was fully functional. Ok, mystery solved. The original display has a bad camera.

I did replace the small video cable. Camera 5V does appear on the T-CON board. L4002/3 have good continuity.

No. That’s how I knew that the ALS wasn’t working. No screen dimming and no automatic keyboard backlight.

Ok, connecting a newer A1990 display did not restore camera functionality.

I don’t have a display this old. I assume A1990 is not compatible?

Customer states that this A1707 machine experiences intermittent keyboard glitches. Inspection showed nothing strange and no liquid damage. However, camera and light sensor are nonfunctional. I verified that the ferrite bead L4004 is good, PP5V_S0_ALSCAM_F is at 5.1V, and the I2C data lines...

The DFU Restore times out because the target machine drops itself out of DFU mode.

Yes, all tests done with good battery, Apple charger, and trackpad.

This board had minor liquid damage in the area around U9080 (NAND power supply). PPBUS is 12.6V. No shorts on the big coils. G3S rails are present. PP2V5_NAND_SSD0 is 2.5V. Trackpad clicks. DFU Restore times out (the board exits DFU mode during the Restore).