History: Dog piss on logic board (yes, customer admitted to dog piss).
Was turning on but no backlight, had major damage to the backlight and intMD/lvds area. Stripped the intMD/lvds connector and replaced all the components (fuse, 1012 caps, coil etc) until i got 0.542 diode mode reading on backlight output. Checked for shorts to ground on all replaced components. Lp8550 feedback was fucked so ran a wire, that was all good.
Plugged in AC (known good Apple original 85w) got fan spin for 2 seconds then powered off. Now when AC power applied machine does not spin fans or go on from S4 > S4 state.
Checked backlight fuse (still good), re-checked backlight area for shorts, still good.
Removed the backlight fuse to see if anything further up was causing it, but no change.
Then back to testing power rails (results below) i've tried to follow this back through the schematic as far as i can but i'm getting a bit lost. Here are the readings i have taken so far.
S5 rails
PPBUS_S5_HS_COMPUTING_ISNS present
PPBUS_G3H present
PPBUS_S5_HS_OTHER_ISNS present
PPDCIN_G3H_ISOL 16.6v present
PPVRTC_G3H 3.3v present
PP3V3_S5 3.3v present
PP5V_S4RS3 missing
PP3V3_S4 missing
U8080 0v at pin 2/3 (enable pin)
5v present at pin 29 of U7501
Q7520 pin 1/3 8.5v all other pins 0
U7501 pin 4 P5VS4RS3_EN_R is 0v)
U7501 pin 21 P3V3S5_EN_R is 3.4v
so i believe the problem is on U7501 not turning P5VS4 on
R7551 is showing as 0.5ohm
C8175 appears to be missing from the board - is this so ?
R8177 is missing also....
R8179 is present on the board (PM_SLP_S4_L) and is 0v
R1461 (PM_SLP_S4_L nearest SMC) 0v
SMC_ONOFF_L is 3.4v at C4834 and at R5170.
I realise these PM_SL_S4_L issues are tricky but am hoping the Rossman / Duke gods can suggest anything that can help before i move on.
Was turning on but no backlight, had major damage to the backlight and intMD/lvds area. Stripped the intMD/lvds connector and replaced all the components (fuse, 1012 caps, coil etc) until i got 0.542 diode mode reading on backlight output. Checked for shorts to ground on all replaced components. Lp8550 feedback was fucked so ran a wire, that was all good.
Plugged in AC (known good Apple original 85w) got fan spin for 2 seconds then powered off. Now when AC power applied machine does not spin fans or go on from S4 > S4 state.
Checked backlight fuse (still good), re-checked backlight area for shorts, still good.
Removed the backlight fuse to see if anything further up was causing it, but no change.
Then back to testing power rails (results below) i've tried to follow this back through the schematic as far as i can but i'm getting a bit lost. Here are the readings i have taken so far.
S5 rails
PPBUS_S5_HS_COMPUTING_ISNS present
PPBUS_G3H present
PPBUS_S5_HS_OTHER_ISNS present
PPDCIN_G3H_ISOL 16.6v present
PPVRTC_G3H 3.3v present
PP3V3_S5 3.3v present
PP5V_S4RS3 missing
PP3V3_S4 missing
U8080 0v at pin 2/3 (enable pin)
5v present at pin 29 of U7501
Q7520 pin 1/3 8.5v all other pins 0
U7501 pin 4 P5VS4RS3_EN_R is 0v)
U7501 pin 21 P3V3S5_EN_R is 3.4v
so i believe the problem is on U7501 not turning P5VS4 on
R7551 is showing as 0.5ohm
C8175 appears to be missing from the board - is this so ?
R8177 is missing also....
R8179 is present on the board (PM_SLP_S4_L) and is 0v
R1461 (PM_SLP_S4_L nearest SMC) 0v
SMC_ONOFF_L is 3.4v at C4834 and at R5170.
I realise these PM_SL_S4_L issues are tricky but am hoping the Rossman / Duke gods can suggest anything that can help before i move on.