A1534, 820-00045 no backlight

Don Anton

New member
Hi Louis, Duke, and all the other great people,

I have this 820-00045 board no back light. no liquid damaged but some one has lift the lcd connector and came as no backlight. How ever I replaced the LCD connector still no back light but I can see the background witha light.

I check voltages and PPVOUT_S0_LCDBKLT is 0.4v but some times 0v

u7701 pin 9/10 get 8.66v and 8.67v from the current sense .

EDP_BKLT_EN IS 3.4V

I2C_BKLT_SCL 5V ON PIN 15

I2C_BKLT_SDA 5V ON PIN 16.

Q7706 not opening the gate and send power on pin 6,5,2,1 as BKLT_SD is 8.6v. I checked R7702 AND R7701 both accurate.

Is this becoz of LCD connector? any clue?
 

2informaticos

Administrator
Staff member
Any idea why the connector has been removed?
Should be good idea to test known good LCD assembly.
PRAM reset done?

Be sure to have continuity between J8300 and all corresponding components...
Check D7701 for short; also post resistance to ground on both pins.
R7710/11 OK?
Try other U7701 too.

"Q7706 not opening the gate and send power on pin 6,5,2,1 as BKLT_SD is 8.6v."
That means bad Q7706; start changing it.
It requires 0V at BKLT_SD to get open...
 

Don Anton

New member
Hi, Thank you for your quick reply.

LCD connector removed as it was broken. some one tried to remove the cable wrong way.

there is no short on D7701 . resistance to ground 0.566v
R7710/11 BOTH ARE OK . replaced u7701 still same. replaced q7706 no dice.
 

Don Anton

New member
but I think q7706 is works the way it should be. it is not sending signals as the gate voltage is not lower than source. current sensing works and datat lines are fine. could this be the connector?
 

2informaticos

Administrator
Staff member
"Q7706 not opening the gate and send power on pin 6,5,2,1
--------------
it is not sending signals"
Please provide accurate information; you make opposed afirmations in two posts..,
You cannot get voltage at L7710 if Q7706 is off.
 
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