I have 820-00239 board which is working perfectly only with keyboard flex disconnected. Customer says, that computer was dropped. In most cases when I plug keyboard flex in (J4500) computer starts, shows Apple logo, loads system halfway and shuts down. Sometimes it lets me to write password, I can get to OS, but few seconds later it restarts. After disconnecting keyboard it works perfectly for hours. I took it to Apple, it got topcase and keyboard replaced but it hasn't solved problem. As there are fan power and data lines I've disconnected them from keyboard and tried without them - the same result. I've inspected board for damages, but haven't found any. It seems that keyboard flex causes problem on some communication line, but schematic doesn't help at all.
Diode mode readings of J4500 with everything disconnected from the board:
PP5V_S0_FAN_CONN - 0,431v
FAN_RT_TACH - OL
FAN_LT_TACH - OL
FAN_RT_PWM - 0,496v
FAN_LT_PWM - 0,496v
PP5V_S0_KBD - 0,430v
KBD_I2C_SDA - OL
KBD_INT_L - OL
KBD_I2C_SCL - OL
SMC_LSCO_RST_L - 0,707v (when board turned on gets 3,3v both with and without keyboard)
KBD_BLC_GSSCK - OL
KBD_BLC_GSSOUT - OL
KBD_BLC_GSLAT - OL
KBD_GLC_GSSIN - OL
KBD_GLC_XBLANK - OL
PP3V3_S4 - 0,315v
Diode mode readings of J4500 with keyboard connected:
PP5V_S0_FAN_CONN - 0,410v
FAN_RT_TACH - 0,406v
FAN_LT_TACH - 0,410v
FAN_RT_PWM - 0,496v
FAN_RT_PWM - 0,496v
PP5V_S0_KBD - 0,412v
KBD_I2C_SDA - 0,421v
KBD_INT_L - 0,550v
KBD_I2C_SCL - 0,554v
SMC_LSCO_RST_L - 0,434v
KBD_BLC_GSSCK - 0,676v
KBD_BLC_GSSOUT - 0,491v
KBD_BLC_GSLAT - 0,675v
KBD_GLC_GSSIN - 0,676v
KBD_GLC_XBLANK - 0,675v
PP3V3_S4 - 0,315v
I have also checked J4501, everything looks OK there. As I haven't found any chip on the board related to keyboard controll I understand, that it should be somewhere on keyboard itself, but I think it's not the problem here. The problem seems to be related to communication between board and keyboard, but I don't know where to look. Does SMC have any role here as there are comunication lines in connector?
Diode mode readings of J4500 with everything disconnected from the board:
PP5V_S0_FAN_CONN - 0,431v
FAN_RT_TACH - OL
FAN_LT_TACH - OL
FAN_RT_PWM - 0,496v
FAN_LT_PWM - 0,496v
PP5V_S0_KBD - 0,430v
KBD_I2C_SDA - OL
KBD_INT_L - OL
KBD_I2C_SCL - OL
SMC_LSCO_RST_L - 0,707v (when board turned on gets 3,3v both with and without keyboard)
KBD_BLC_GSSCK - OL
KBD_BLC_GSSOUT - OL
KBD_BLC_GSLAT - OL
KBD_GLC_GSSIN - OL
KBD_GLC_XBLANK - OL
PP3V3_S4 - 0,315v
Diode mode readings of J4500 with keyboard connected:
PP5V_S0_FAN_CONN - 0,410v
FAN_RT_TACH - 0,406v
FAN_LT_TACH - 0,410v
FAN_RT_PWM - 0,496v
FAN_RT_PWM - 0,496v
PP5V_S0_KBD - 0,412v
KBD_I2C_SDA - 0,421v
KBD_INT_L - 0,550v
KBD_I2C_SCL - 0,554v
SMC_LSCO_RST_L - 0,434v
KBD_BLC_GSSCK - 0,676v
KBD_BLC_GSSOUT - 0,491v
KBD_BLC_GSLAT - 0,675v
KBD_GLC_GSSIN - 0,676v
KBD_GLC_XBLANK - 0,675v
PP3V3_S4 - 0,315v
I have also checked J4501, everything looks OK there. As I haven't found any chip on the board related to keyboard controll I understand, that it should be somewhere on keyboard itself, but I think it's not the problem here. The problem seems to be related to communication between board and keyboard, but I don't know where to look. Does SMC have any role here as there are comunication lines in connector?