(347) 552-2258 [email protected]

A1990 820-01827

ipetro

ipetro

Member
the board starts at 20v\0.780a and then drops to 0.289a and freezes.

when examining the board I found that the c6700 literally exploded!

I checked PP5V_G3S=21 ohm (should be kilo-ohms), there is no short circuit!
there is no circuit for this board, so I use 820-01041, which complicates the identification of chips.

under the thermal imager the only thing is that the unknown chip heats up a little, when it is removed the resistance on the PP5V_G3S=21 ohm line remains unchanged 21 ohm.
need help from professionals
 

Attachments

  • photo_1_2025-01-15_23-58-58.jpg
    photo_1_2025-01-15_23-58-58.jpg
    184.1 KB · Views: 1
  • photo_3_2025-01-15_23-58-58.jpg
    photo_3_2025-01-15_23-58-58.jpg
    236.6 KB · Views: 1
  • photo_2_2025-01-15_23-58-58.jpg
    photo_2_2025-01-15_23-58-58.jpg
    67.4 KB · Views: 1
ipetro

ipetro

Member
That's exactly what I did, I applied 1 volt and raised it to 5 volts and only one element barely heated up, the one in the photo (I don't know what kind of microcircuit it is). The 5V_G3S line consumes 0.17 A when applying 5.5 volts
 
ipetro

ipetro

Member
after replacing U8110, U3500, UB700, the 5V_G3S resistance dropped to 0.766 com. the MacBook turns on and charges! the touchbar, keyboard backlight, etc. work, but there is no picture on either the external or internal display (I put the board in another case with a tested display, nothing changed)
 
ipetro

ipetro

Member
J8500
pin1=0.421
pin2=0.421
Of course I checked the connection to an external monitor with and without the LCD connected, as well as both aux outputs on the J8500
 
ipetro

ipetro

Member
EDP_PANEL_PWR_EN =0v (diodmod=0,499 ) (0.42 kohm)
EDP_PANEL_PWR_DLY_EN=0v(dm=0,638) (0.478 mohm)
3V3V_S0SW_LCD=0.457 (0.382mohm)
5V_S0SW_LCD=0.538 (4 mohm)
 
ipetro

ipetro

Member
I can say with certainty that the problem is not with the U9850. I replaced it twice with new ones, it has no effect at all and everything is the same.
It seems to me that I have absolutely no power supply to the GPU. I have absolutely no voltage around the Ua000. Perhaps the problem is with the power supply to the GPU?
 
ipetro

ipetro

Member
this is exactly what I did when I found myself at a dead end and decided to write to you. I compared everything with the same board and the readings are almost identical. both in resistance mode and in diode mode.
the initial problem was in the blown up C6700 due to a faulty trackpad. and high resistance PP5V_G3S. it seems to me that we need to move in this direction. what else could have died?!
 
You must log in or register to reply here.
Top