820-3462 came in for liquid damage. Keyboard needed replacing and the backlight is out. I have already replaced the keyboard, but am stuck on the backlight. Hoping someone here can help.
I have verified that it is indeed a no backlight problem by shining a light through the Apple logo on the back of the display. I can make out the screen.
The computer works fine when connecting to external monitor.
I cleaned the board of what little liquid spill I could see and found the backlight fuse to be blown. I replaced it. Still no backlight.
I replaced the backlight driver IC (LP8545SQX-EXTJ, U9701) - Still no backlight.
Measurements (Battery not connected only power adapter, display cable connected.):
Pin 1 of J9000 - 12.56V
F9700 - 12.56V on both sides
Pin 4 of Q9706 (PPBUS_S0_LCDBKLT_FUSED)- 12.56V
Pin 1 of Q9706 (PPBUS_SW_LCDBKLT_PWR) - 12.51V
Pin 1 of L9710 (PPBUS_S0_LCDBKLT_PWR) - 12.51V
Pin 2 of L9710 (PPBUS_S0_LCDBKLT_PWR_SW) - 12.51v
Pin 1 of D9701 - 12.58V
Pin 2 of D9701 - 12.51V
Pin 21 of U9701 (BKL_FB) - 0.1V
Pin 4 of U9701 (BLK_EN) - 3.08V
Pin 2 of U9701 (LVDS_BKL_PWM_RC) - 3.32V
Pin 2 of C9719 - (PPVOUT_S0_LCDBKLT) - 12.58V
I'm stumped. Can somebody guide me from here? Thanks.
I have verified that it is indeed a no backlight problem by shining a light through the Apple logo on the back of the display. I can make out the screen.
The computer works fine when connecting to external monitor.
I cleaned the board of what little liquid spill I could see and found the backlight fuse to be blown. I replaced it. Still no backlight.
I replaced the backlight driver IC (LP8545SQX-EXTJ, U9701) - Still no backlight.
Measurements (Battery not connected only power adapter, display cable connected.):
Pin 1 of J9000 - 12.56V
F9700 - 12.56V on both sides
Pin 4 of Q9706 (PPBUS_S0_LCDBKLT_FUSED)- 12.56V
Pin 1 of Q9706 (PPBUS_SW_LCDBKLT_PWR) - 12.51V
Pin 1 of L9710 (PPBUS_S0_LCDBKLT_PWR) - 12.51V
Pin 2 of L9710 (PPBUS_S0_LCDBKLT_PWR_SW) - 12.51v
Pin 1 of D9701 - 12.58V
Pin 2 of D9701 - 12.51V
Pin 21 of U9701 (BKL_FB) - 0.1V
Pin 4 of U9701 (BLK_EN) - 3.08V
Pin 2 of U9701 (LVDS_BKL_PWM_RC) - 3.32V
Pin 2 of C9719 - (PPVOUT_S0_LCDBKLT) - 12.58V
I'm stumped. Can somebody guide me from here? Thanks.
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