[SOLVED]820 3437 B, No backlight

[Noguinfor]

Hey guys,

I dont have backlight in this board. No liquid damage.

D7701 - pin 1 = 7.07 pin 2 = 20.1V

Fuse ok !!

any idea ?

 

[smiba]

BKL_PWM voltage?

 

[Noguinfor]

Bkl_pwm = 1.8v

 

[dukefawks]

PRAM reset first. PWM is too low.

 

[Noguinfor]

when i try to PRAM reset a padlock appears... i can enter in ios.. have to some way to know the password inside ios?

 

[smiba]

Ask the customer for the EFI Lock password or if the login in OS X allows you to select "Other user" you might be able to try to login with the "root" user trick (User root, password empty. Try this two times), the device might not have updated yet

 

[Noguinfor]

i know the login password to enter in OS X! But the password isn't the same as the padlock ..

 

[smiba]

Try to login onto the computer and set the brightness to full, at least that way we know for sure it isn't simply turned off.
I recommend just asking the customer for the EFI lock though so we can do a full PRAM reset....

 

[Noguinfor]

good idea smiba, unfortunately don't work.. i already ask a password to client, i'm waiting.. but clients usually forget the firmware password.. ty for rply

 

[Noguinfor]

Ok, i already remove a efi password and I already do a PRAM reset.... But don't have BKLT! after diode D7701 - pin 1 = 7.07 pin 2 = unstable 24v - 30V ... suggestions ??

 

[dukefawks]

Replace LP8550. Although 30V should usually give some backlight. Known good LCD? Also check feedback trace to ball A5 on LP8550 of course.

 

[Noguinfor]

Ok Duke you are right!! LP8550 replaced and works fine.. you can close the post .. thank you