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08 Jul

Background:

New MacBook Pro 15″ has been water-damaged, fully functional except the touch bar not working. Apple quoted $2000 for replacing the entire logic board. MacBook Model Number A1990 Year 2018 Logic Board Number 820-01041-07.

Diagnosis:

This latest model was just released a few months ago cost $4000+.There is no schematic (electronic circuit diagrams), no chips info available and it is our first time working on this new model. The touch bar connector on the logic board has been burned badly. We noticed the touch bar part number on this mac is the same one used on the 2017 model. So the power and control signals of the connector must be the same! We can refer to the schematic of the 2017 model to make “intellectual guess” based on the chips used on this new logic board.

Repair:

Pull out the logic board from the case, remove the burned connector. As always the case for a liquid-damaged board, some of the connector pins are gone, and 99% of them are power supply pins. Since there is no schematic for this model, we have to refer to the 2017 model schematic as shown below:

Touch bar connector J4402 pin 20,21 PP1V8_S0SW_DFR 1.8V power supply and pin 22 PP5V_S0_T139 5.0V power supply are all gone! The traces are from underneath layers of the board, and we can not trace them to the sources by microscope. Where are these powers come from? There is no schematic, no board view to guide us, so we have to go back to the old, time consuming, frustrating method: continuity test.

After a lengthy, cautious, painful 6 hours repair, we finally manage to fix it! The job could have been done within 2-3 hours if schematic available.

Just confirm that Apple has removed the “lifeboat” port on this new logic board. There is NO WAY to retrieve data from the onboard SSD chips of a faulty board. If the logic board is not repairable (e.g., CPU damaged), or replaced by Apple genius bar as they always do, all the data is gone. A user must do a regular backup to protect data.

This article is written by IT-Tech Online, the MacBook repair specialist in Melbourne.