As it's my first post on this forum I want to say hello to all members!
I'm fighting with a kind of odd case of A1708, board number 820-00840. Board looks perfectly clean, untouched, no water signs, no damages, even no dust on it. Customer claims, that computer just turned off by itself and stopped charging.
First measurements:
- no 20v on charger, stuck at 5v
- PP3V3_G3H 2,5v (no short, 0,337v in diode mode)
- PPBUS_G3H 0,115v (no short, 0,386v in diode mode)
I've noticed U6990 and SMC were getting hot (SMC was warmer), so replaced U6990 first. No results, PP3V3_G3H still at 2,5v. Later I've replaced SMC from the same board which has brought PP3V3_G3H back to 3,3v, U6990 not getting hot anymore too. Board switched to 20v 0,039A on charger, but still not powering on. Weirdly, when I was heating up the area around SMC, the PPBUS_G3H raised to 13v and board booted taking around 1A. After connecting screen I had logo with progress bar, but before it loaded fully, board cooled down and turned off. I thought it's just bad soldering, so I pulled SMC, reballed and put it back. No changes, but this time it takes much longer for board to swicth to 20v or sometimes it stays at 5v 0,05A. Now heating SMC area doesn't make it to "boot" like before. When it takes 20v anyway there is no PPBUS.
- Here are basic voltages I'm getting (diod modes in brackets)
- PP3V3_G3H - 3,3v (0,334)
- PP20V_USBC_XA/XB - 20v or sometimes stuck at 5v (0,158)
- PP3V3_UPC_XA/XB - 3,3v
- PPBUS G3H - 0,037v (0,385)
- PP3V3_S5/PP5V_S5 - 0v obviously, there is no PPBUS (0,345/0,398)
- readings around D6905 (I've replaced it just in case):
pin 1 - 20v (0,381)
pin 2 - 0,037v (0,515)
pin 3 - 20v (0,510)
R6905: both sides reads 0,037v, resistance OK.
- U7000 replaced twice, here are readings around:
PPVIN_G3H_P3V3H3H - 20v
TBA_CSIR_N - 20v
TBA_CSIR_P - 20v
TBA_COMP - 1,15v
TBA_LX1 - 0v
TBA_BOOT1 - 4,86v
TBA_VDDP - 5,15v
TBA_VDDP - 5,15v
TBA_BOOT2 - 4,92v
current sense:
TBA_CSIR_P/TBA_CSIR_N - 2,5ohm
TBA_CSOR_P/TBA_CSOR_N - 2,7ohm
other readings:
TBA_HPWR_EN_L - 3,38v (resistance OK)
BUF_SMC_RESET_L - 3,40v
PP3V3_S5_SMC_VDDA - 3,4v
SMC_WAKE_L - 3,1v (shold be low, right?)
PP1V2_S5_SMC_VDDC - 1,20v
PP3V0_S5_AVREF_SMC - 3,0v
All resistors around SMC checked, nothing is missing, values are correct. Voltages at U6100 not present, but I think it's because PPBUS is missing. Do you have any suggestions? Can it be bad SMC again?
I'm fighting with a kind of odd case of A1708, board number 820-00840. Board looks perfectly clean, untouched, no water signs, no damages, even no dust on it. Customer claims, that computer just turned off by itself and stopped charging.
First measurements:
- no 20v on charger, stuck at 5v
- PP3V3_G3H 2,5v (no short, 0,337v in diode mode)
- PPBUS_G3H 0,115v (no short, 0,386v in diode mode)
I've noticed U6990 and SMC were getting hot (SMC was warmer), so replaced U6990 first. No results, PP3V3_G3H still at 2,5v. Later I've replaced SMC from the same board which has brought PP3V3_G3H back to 3,3v, U6990 not getting hot anymore too. Board switched to 20v 0,039A on charger, but still not powering on. Weirdly, when I was heating up the area around SMC, the PPBUS_G3H raised to 13v and board booted taking around 1A. After connecting screen I had logo with progress bar, but before it loaded fully, board cooled down and turned off. I thought it's just bad soldering, so I pulled SMC, reballed and put it back. No changes, but this time it takes much longer for board to swicth to 20v or sometimes it stays at 5v 0,05A. Now heating SMC area doesn't make it to "boot" like before. When it takes 20v anyway there is no PPBUS.
- Here are basic voltages I'm getting (diod modes in brackets)
- PP3V3_G3H - 3,3v (0,334)
- PP20V_USBC_XA/XB - 20v or sometimes stuck at 5v (0,158)
- PP3V3_UPC_XA/XB - 3,3v
- PPBUS G3H - 0,037v (0,385)
- PP3V3_S5/PP5V_S5 - 0v obviously, there is no PPBUS (0,345/0,398)
- readings around D6905 (I've replaced it just in case):
pin 1 - 20v (0,381)
pin 2 - 0,037v (0,515)
pin 3 - 20v (0,510)
R6905: both sides reads 0,037v, resistance OK.
- U7000 replaced twice, here are readings around:
PPVIN_G3H_P3V3H3H - 20v
TBA_CSIR_N - 20v
TBA_CSIR_P - 20v
TBA_COMP - 1,15v
TBA_LX1 - 0v
TBA_BOOT1 - 4,86v
TBA_VDDP - 5,15v
TBA_VDDP - 5,15v
TBA_BOOT2 - 4,92v
current sense:
TBA_CSIR_P/TBA_CSIR_N - 2,5ohm
TBA_CSOR_P/TBA_CSOR_N - 2,7ohm
other readings:
TBA_HPWR_EN_L - 3,38v (resistance OK)
BUF_SMC_RESET_L - 3,40v
PP3V3_S5_SMC_VDDA - 3,4v
SMC_WAKE_L - 3,1v (shold be low, right?)
PP1V2_S5_SMC_VDDC - 1,20v
PP3V0_S5_AVREF_SMC - 3,0v
All resistors around SMC checked, nothing is missing, values are correct. Voltages at U6100 not present, but I think it's because PPBUS is missing. Do you have any suggestions? Can it be bad SMC again?