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820-3330 missing bkl_pwm
- Thread starter shanenin
- Start date
Normal voltage is 39V there.
Do PRAM reset and comment.
Do PRAM reset and comment.
shanenin
Member
changed the backlight driver and I am back up to 27.8v. Since the speakers are connected to the board on this model, I should be hearing it chime when resetting the pram(but it did not)? I did hear it chime originally when first looking at the computer before removing the logic board
Do you get USB activity?
If yes, look at USB mouse light.
If PRAM works, its light should go off/on; use it instead of chime.
BTW, you can force again the backlight, to have control on the screen; or use external monitor, if possible.
I bet it has EFI password and PRAM reset cannot be done in "blind way".
If yes, look at USB mouse light.
If PRAM works, its light should go off/on; use it instead of chime.
BTW, you can force again the backlight, to have control on the screen; or use external monitor, if possible.
I bet it has EFI password and PRAM reset cannot be done in "blind way".
You must keep pressing the PRAM reset keys until USB mouse light comes on again.
In fact you are using its light instead of chime.
In fact you are using its light instead of chime.
I only saw this problem on machines with EFI password.
The last one 3 days ago...
The last one 3 days ago...
I doubt you can get backlight with less than 34V.
Be sure to measure correctly.
Be sure to measure correctly.
