Updated: Jul 25
APPLE MACBOOK PRO 15 TOUCH BAR 2018 X1190 MLB 820-01041 A 051-02643 REV4.0.0
Device came in for liquid damage repair, there is also a previous repair attempt.
Damage to C9081 with Short on PPBUS_GH3_SSD0_SNS.
Short on PPBUS_GH3_SSD0_SNS persists.
Injected power on shorted line, u9080 overheating on thermal imaging.
Removed u9080, short persists. Removed c9073, c9080, c9074, short persists.
Isolated short by removing R5620. There are now no components left on PPBUS_GH3_SSD0_SNS yet it is still short.
The line PPBUS_GH3_SSD0_SNS is short inside the PCB.
1. Scrape at the logic board hoping that the short disappears, or drill a hole through the board also hoping shorts disappears and nothing else is damaged...
2. Create a new line with a jumper wire on the board, while hoping no other lines were affected by the short on PPBUS_GH3_SSD0_SNS.
After isolating the shorted line and attempting to connect to power, there is additional shorts on PCB. Device also has a short on DB500 (NSR20F40NXT5G) line PP20V_USBC_TA_VBUS. This is a voltage overprotection diode.
Removed DB500. Short is gone on PP20V_USBC_TA_VBUS.
On Additional inspection of the board, There is also missing components DB554 and DB549 These are ESD PROTECTION diodes.
The device may be able to function without these protection diodes.
Added jumper for PPBUS_GH3_SSD0_SNS but wasn't sure that they could handle the power line that well, so I replaced them for something more sturdy.
These jumpers seemed too small....
so I replaced with a bigger jumper. unfortuantely still there was no power on the device.
In the end, no fix.