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820-01987 board with 20V but no startup

S

sekidata

Member
This 2020 A2289 board shows 20V on USB-C, pulling 0.05A-0.16A. No liquid damage. I have PPBUS at 12.6V (dropping to 12.3 every 20s or so) and the SLP, AWAKE, and G3S rails are all present. No obvious shorts on the big coils.

SSD rails are all there. CPU area gets mildly warm but not hot.

I have tried DFU Revive and Restore, which both end in the padlock on the host computer but no video or change in status on the target machine.

What could I be missing?
 
S

sekidata

Member
Customer says that the screen went out, then it stopped chiming. I tested the screen and it was missing its backlight (I replaced the 49B1-04 backlight chip on the T-con board and the screen works now).

I only have data on the big coils from a similar model (A2159, 820-01598), do you have exact match measurements?
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
Not sure if DFU does an exhaustive check on the NANDs.
The 20s cyling usually points to SSD problems.
Some NAND may have bad locations.
 
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