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Just discovered that with only the charger connected, PPBUS is at 12.6V but the board is missing PP5V_G3S. As soon as I plug in a battery, 5V G3S appears and the machine starts up.
I also just noticed that the board does not start up when no battery is connected - I believe that's wrong for this model. Without the battery, the USB-C meter reads 20V but only 0.07A and no startup.
I measured several rails from page 66 and some others. Does this look as it should?
Not energized:
PP1V1_S3: 0
PP0V6_S3: 0
PP1V8_S3: 0
PPVCC_S0_CPU: 0
PP1V8_S0SW_CPU: 0
PM_SLP_SUS_L: 0
PM_SLP_S3_L: 0
Energized:
PPBUS_G3H: 11.8
PP5V_G3S: 5.1
PP3V3_G3H: 3.3
PP3V3_S5: 2.0
PP1V8_G3S: 1.8...
This A2179 Air arrived dead after customer dropped it. One of its USB-C ports showed 20V, the other 5V. I replaced both CD3217s from an identical donor board and the machine appeared to work fine.
However, when the computer is shut down, the battery continues draining (about 10-15% in 6 hours)...
I ended up checking all lines in the USB-C area that run between front and bottom logic board. I found 8 broken or intermittent lines, so this board surely has plenty of internal damage. I'm saying good-bye to it.
Yes, I agree. But which ones do I check?
I measured the CC lines and the I2C_UPC bus lines for all possible combinations of CD3215s and USB-C plugs. See attached.
I checked the lines between XA and XB (I2C_UPC_X) and they are all good. I did find two missing connections between XA and the redriver U3000 (I2C_UPC_X_DBG_CTL), but those should not matter for the inter-CD3215 communication, right?
Yes, cycling PPBUS 12.6V for 15-20s, then 12.3 for 2s.
Checked NAND seating and solders and all are ok. Of course, there's no guarantee that the NANDs were fully functional on the donor board...
Replacing all 5 NANDs removed the shorts on P1V8_SSD0 and P2V5_NAND_SSD0 and I now measure all correct voltages. But the machine is stuck at 20V 0.04A with no startup.
No shorts on the big coils. DFU Restore fails with error 9.
PPBUS is cycling back and forth between 12.6V and 12.3V. With...
I get one brief flash on my USB mouse, then nothing. No external video. No Caps Lock light.
PPVCC_S0_CPU is initially 0.97V, then stabilizing at 0.87V.