Hi. Have a logic board (820-01958 from A2179 chassis) that is not booting.
Adapter voltage is 20v @ ~70-80mA consumption.
PPBUS_G3H @ 12v29 (should be 12v6). The SMBUS lines on U7000 (ISL9240) are stuck low but there is no short circuit and the level shifters are fine.
Based on the assorted voltage rail review, this board is similar to a case on the Rosmann forum where a DFU is recommended.
At this time, we do not have such a current macbook to perform this DFU process.
Q: What exactly does the DFU process do with respect to the firmware upgrade? That is, which device holds this corrected firmware?
U3060 = TBT ROM storage but we are negotiating fine @ 20V. So we can ignore this device.
U4770 = Is this the T2 rom? (SOC)
Respectively - can the T2 rom (U4470) be applied from a donor board to mimic the DFU process? If only to test if this logic board is capable of working or not, wish to transplant from the donor board.
Do not want to lose any potential data on the non-working target board in this process.
Welcome all suggestions.
Adapter voltage is 20v @ ~70-80mA consumption.
PPBUS_G3H @ 12v29 (should be 12v6). The SMBUS lines on U7000 (ISL9240) are stuck low but there is no short circuit and the level shifters are fine.
Based on the assorted voltage rail review, this board is similar to a case on the Rosmann forum where a DFU is recommended.
At this time, we do not have such a current macbook to perform this DFU process.
Q: What exactly does the DFU process do with respect to the firmware upgrade? That is, which device holds this corrected firmware?
U3060 = TBT ROM storage but we are negotiating fine @ 20V. So we can ignore this device.
U4770 = Is this the T2 rom? (SOC)
Respectively - can the T2 rom (U4470) be applied from a donor board to mimic the DFU process? If only to test if this logic board is capable of working or not, wish to transplant from the donor board.
Do not want to lose any potential data on the non-working target board in this process.
Welcome all suggestions.
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