MacBook Pro 16 inches 820-02100 No Backlight

huzeafa

Member
Good day everyone and happy new year, I have 16 inches 820-02100 with No Backlight. I have used a known good screen and also tested its screen on another device, the screen is not the problem, there is no liquid damage, no oxidation, or anything related, the logic board is clean but with no backlight, under low light, I can see the desktop background. I compared measurements from a different working unit (exactly 16 inches ) All required voltages are present, there's no short to ground, and also diode mode measurements are identical if not the same, the only difference I found was by the backlight output voltage, schematic says its 15V total output when the machine starts on a working board, I, measure around 15V but when the device booted, with a load on the line, the voltage drop to about 11V or so, however, on the device without backlit the voltage does not drop, it remains at 14.7V which is suggestive to me in my opinion that there's no load, I then made a diode mode measurement on the line and also confirm the line is not broken, but everything checked out, still no backlight. Please help me with what to do, I have no idea what more to do.
 

huzeafa

Member
Thank you for getting back : yes I get BL_PWR_EN_R, all signals are exactly the same thing with a working board, the only difference is the backlight output voltage at 14.7V, doesn't that mean the circuit is boosted but no load from the screen?
 

2informaticos

Administrator
Staff member
The good board has also 15V at the beginning and no backlight untill boots.
So there is no load problem, but communication.

Did you check RP881 and all resistors from page 112?
 

huzeafa

Member
Thank you, this was sorted, I can't exactly say, how, there was no board work: not sure exactly why .
 
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