I have this macbook with no backlight and not charging. I have taken the board out plugged the charger in and it blows the p7 transistor on the dc in board, when the board is in the machine it dosnt show a light when plugged in and it dosnt blow the p7 , only when the board is out of the machine . works on battery with no backlight i can see the circle with a line through it on the screen.
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820-4924 dc board and backlight issue.
- Thread starter THEDUDE
- Start date
DCIN board doesn't have any transistor.
That is a TVS diode, like BAT30CW, or RCLAM2402.
If get it blown, means an overvoltage occured.
It can be caused by fake charger.
Original charger generates aprox (only) 3V when is connected; for Magsafe 2 case.
Its processor allows full voltage if no problem detected in the machine.
Fake charger has no processor inside and always gives out full voltage.
That's the reason of many power problems in MacBooks...
Be sure to use original Magsafe 2 charger 60/85W.
Do NOT use Magsafe 1 to 2 adapter, as you can have backlight issue on this model.
That is a TVS diode, like BAT30CW, or RCLAM2402.
If get it blown, means an overvoltage occured.
It can be caused by fake charger.
Original charger generates aprox (only) 3V when is connected; for Magsafe 2 case.
Its processor allows full voltage if no problem detected in the machine.
Fake charger has no processor inside and always gives out full voltage.
That's the reason of many power problems in MacBooks...
Be sure to use original Magsafe 2 charger 60/85W.
Do NOT use Magsafe 1 to 2 adapter, as you can have backlight issue on this model.
Back again 
so i got the new dc board and genuine charger all is good there. the mac fires up and i can see a faint pic so backlight problem there ' the main issue is the charger light is flickering and not powering the machine or charging the battery.i have checked PP18V5_DCIN_CONN power rail i get 16.8v . can you guide me on where to go next please
so i got the new dc board and genuine charger all is good there. the mac fires up and i can see a faint pic so backlight problem there ' the main issue is the charger light is flickering and not powering the machine or charging the battery.i have checked PP18V5_DCIN_CONN power rail i get 16.8v . can you guide me on where to go next please
Resistance to ground (diode mode) at D7710, both pins.
Also post some voltages for U7700, pins 5, 18, 17, 11.
Also post some voltages for U7700, pins 5, 18, 17, 11.
"u7700 pin 5 0v pin 18 0v"
Check resistance to ground now.
If =PP5V_S0_BKLT is present, then check R7144/45.
Check resistance to ground now.
If =PP5V_S0_BKLT is present, then check R7144/45.
It comes from U8080 through R5530.
Check pin 1 trace.
It should have 5V, as it comes from L7520.
It should have 5V, as it comes from L7520.