Hey guys, just troubleshooting a MacBook Pro A2289 with the 820-01987 logic board.
No fan spin, no booting, device not getting detected by the Apple Configurator.
Did a few basic things, the board gets to 20V USB supply according to my USB tester, F7000 fuse seem to be ok and not blown.
Board draws about 0.5A for about 10 seconds, after that it goes down to 0V. Found an n channel FET (Q4830) in the backlight supply(?) that could to be blown (pictures below), not quite sure about that, but t assume that should not be relevant, because I was testing the board standalone and disassembled from the MacBook with the USB C supply only.
After about 10 seconds the current draw from the USB supply decreases to 0A.
CPU is getting 0,85V during the 10 seconds.
Been able to figure out there is a short circuit on the board at C4511 and all other Caps between PP1V8_SLPS2R and GND.
On the thermal image U3900 seems to get pretty hot, because even the metal shielding gets hot to some point and heat dissipates through the PCB on the caps below (I know the thermal image is very low resolution, could literally be a surface picture of the sun if you consider the amount of pixels of the image)
That is why I assume U3900 is likely dead. Does anyone know anything about U3900, it sits under the metal shield. Is it publicly available? I assume it's some kind of ASIC, because the name "POP-1GB-20NM-M-SCK" suggests it was manufactured using 20 nanometer technology.
Could the problem be related to the likely seemingness "drop of solder" / bridge on these 2 images or is it meant to be there?
Any suggestions / opinions on further steps / how to continue? Any help would be appreciated
Alex
No fan spin, no booting, device not getting detected by the Apple Configurator.
Did a few basic things, the board gets to 20V USB supply according to my USB tester, F7000 fuse seem to be ok and not blown.
Board draws about 0.5A for about 10 seconds, after that it goes down to 0V. Found an n channel FET (Q4830) in the backlight supply(?) that could to be blown (pictures below), not quite sure about that, but t assume that should not be relevant, because I was testing the board standalone and disassembled from the MacBook with the USB C supply only.
After about 10 seconds the current draw from the USB supply decreases to 0A.
CPU is getting 0,85V during the 10 seconds.
Been able to figure out there is a short circuit on the board at C4511 and all other Caps between PP1V8_SLPS2R and GND.
On the thermal image U3900 seems to get pretty hot, because even the metal shielding gets hot to some point and heat dissipates through the PCB on the caps below (I know the thermal image is very low resolution, could literally be a surface picture of the sun if you consider the amount of pixels of the image)
That is why I assume U3900 is likely dead. Does anyone know anything about U3900, it sits under the metal shield. Is it publicly available? I assume it's some kind of ASIC, because the name "POP-1GB-20NM-M-SCK" suggests it was manufactured using 20 nanometer technology.
Could the problem be related to the likely seemingness "drop of solder" / bridge on these 2 images or is it meant to be there?
Any suggestions / opinions on further steps / how to continue? Any help would be appreciated
Alex
Attached Files
