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A2289 820-01987-A 5v .31ma

T

TBFix

Member
No sign of spillage on the board that I can see.
It draws 5v .31ma .
PPBUS_g3h is 1v diode reading .385. I have tried dfu mode but host Mac can not see it. I tried removing U4770 and reprogramming it but still same.
I cannot find any shorts on the board.
 
2informaticos

2informaticos

Administrator
Staff member
You can't do anything until get PPBUS_G3H at least.

Do you get 5V at U7000?
If yes, post its basic voltages; P_IN, AUX_DET, VDDA/P.
 
T

TBFix

Member
U7000 R7021 and R7022 were both high 87k and small discoloration on U7000 so changed both resistors and now getting 20v 0.27v, PPbus_G3h is now 11.2v . I can now get it into dfu mode but it keeps erroring out on host machine. The host is running Big Sur, not sure what the faulty one was running.
 

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T

TBFix

Member
Yes internet is stable. I have tried recover and also revive but errors out on both. Also it shows the recovery screen as in pic when mac is plugged in without pressing any buttons but if you hold power for a few mins the hold all 4 buttons it says DFu not recovery but still the same outcome. Also the target mac screen shows logo with progress bar fully across then disappears then the error in pic shows on host machine.
 
T

TBFix

Member
Is there a special way to do that as I cannot get the host to see the mac with charger and battery disconnected?.
 
2informaticos

2informaticos

Administrator
Staff member
Temporar contact on SE032 pads, to force DFU; without charger, nor battery connected.
The 5V from the other machine (with AC2), will power the board.
 
T

TBFix

Member
Hi thanks for the info but still the same. It just says "The system cannot be restored on this device" and also "Gave up waiting for the device to transition from DFU state to Dfu state". I have tried several different macs, Os and cables.

I have a t2 rom programmer is there any use in flashing U4700? if so any idea where I can find clean dump for this chip.

Thanks
 
2informaticos

2informaticos

Administrator
Staff member
Do you mean U4770?
Some people claim on Internet to revived dead boards reflashing it; no mention about this particular board.

I remember when I flashed SoC ROM between two 01521 and I lost even 20V on USB-C input.
Do not trust all you read on Internet...
 
T

TBFix

Member
Yes that is correct U4770. I was going to look for clean dump for this board to try but can only find the ones that come with the t203 programmer but Im not sure if these are clean or modified dumps.
 
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