Search results

MacBook arrived with no screen backlight and liquid damage in the backlight circuitry around U8400. Replaced all corroded components, including U8400. Now the backlight works but only when I select a very low brightness setting. It disappears when the brightness setting is raised...

Diode readings of J3300 on this board match a good board exactly. I think you're right: there's still an undiscovered corroded component or trace somewhere that's messing things up. I'll keep looking.

On a good board, UPC_I2C_INT_L only changes from 0 to 1.8V when USB-C switches to 20V, so no surprise there. I replaced J3300, with no change.

Sorry, I meant to write that I do get PP1V1_UPC_XB_LDO_BMC when plugging into port B, but not PP1V1_UPC_XA_LDO_BMC when plugging into port A. When I have a battery and the charger connected, plugging into port B gives me 20V but 0A. Nothing at all on port A. No S-UEM2 tester. I checked for...

This 2018 Air came in with liquid damage in the area of the USB-C connector on the logic board. Pins 59 (20V) and 55 (Gnd) on the connector were visibly burnt, and a few nearby caps looked corroded (C6405, C6416, CC711, C3306). After clean-up, USB is now stuck at 5V, drawing 0.08A. PPBUS is at...

Which UR630 pins are you referring to?

There may be PPBUS leakage somewhere but I doubt it's near UR630. I cleaned that area and replaced UR630. By the way, during every boot loop restart PPBUS goes to zero and USB-C voltage drops to 5V briefly.

This 820-02020 had some minor liquid damage in the areas of UR630 (speaker amp), UD540 and UD560 (PP3V3). It is stuck in a boot loop: it chimes, then begins to show the progress bar to around 15-20%, then shuts down and chimes again. This happens with every connector unplugged from the logic...

I'm looking for the SoC ROM bin file for 820-01041-A (A1990 2018 15" MacBook Pro).

Thanks. Worked surprisingly well.

Yup, good bye CPU.

Since the ROM reflashing, the pulsing has changed to a more steady, stagnating state. The CPU rails are at their pre-POST levels and remain there, without the fluctuations usually seen around the chime time (VCore is a steady 0.9 V, for instance). Stays like this for a minute or two, then turns...

I have a 2019 820-01521 board that is MDM (Remote Management) locked due to the previous user's neglect to remove it from the MDM server. What is the best way to return the board to a normal state? I assume it involves reflashing the SoC ROM, as well as replacing the NAND modules?

Any other ideas?

No change after a reflash of the SoC ROM. Still shows video during DFU Restore but never makes it to POST.

Do you have a BIN file?

During the cycling, PPBUS goes from 12.6 to 12.3 V and so forth. Does this implicate the SMC (i.e. T2 chip)?

As I said before, there is no chime, no progress bar, no screen backlight, no response to any startup keys. Just the fans and CPU voltages cycling on and off. I still suspect a short somewhere but haven't found it yet.

Weirdly, that's correct. Sometimes, the DFU Restore fails, but usually I get video on the target machine (see below) and padlock on the host. Still, the machine reverts to cycling instead of chiming and progressing with the startup.

Upon further inspection it looks like this board is cycling: every few seconds I get these rails for several seconds, then back down to 0V: PPVCC_S0_CPU, PPVCCSA_S0_CPU, PPVCCIO_S0_CPU, along with cycling fans.