A1466 No back light

I had 8.5V at the boost circuit output, I have changed the backlight driver and wired the missing feedback line. When I connect the feedback wire input fuse is failing, Not sure why. I don't see any short at output
 

2informaticos

Administrator
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So you get image, only missing backlight?
Post diode mode to ground at both pins of D7701; w/ and w/o LCD connected.

Any history available?
 

2informaticos

Administrator
Staff member
I don't understand what is the problem there.
R/C7704 looks good as their trace to U7701 too.

When feedback is broken (XW7720), this is what you need to do.
 
I have made a connection from the xw7720 n via to D7701cathode.
When I connect the screen I get 0V at o/p, Still, the display image is there.
But Q7706 is not turning ON. Q7706 gate has 8.2V.
When I check Q7707 Gate - the 5th pin is 0V and the 2nd pin is 3.3V.
 

2informaticos

Administrator
Staff member
So missing EDP_BKLT_EN signal.
"I had 8.5V at the boost circuit output"
Impossible without that signal.
Fuse gets burnt again?
 
Now I can see both BKLT_PLT_RST_L and EDP_BKLT_EN are present and 3.3 V but Q7706 is not functioning I mean I get 0V at PPVIN_S0SW_LCDBKLT_FET. And 8.3V at PPVIN_S0SW_LCDBKLTFET.
I don't have Q7707 MOSFETs spare. Am I allowed to connect LCDBKLT_EN_DIV_L directly to Ground for testing purpose?
 
Yes, the problem solved, I have shorted the 1st and 6th pins of Q7707. Found the backlight is present. Then I have replaced the Q7707 with a new one. Now it's perfect. Thanks for the support
 
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