[SOLVED]820-2850 no backlight

RyanLEN

New member
Hi. Board has an Image but no Backlight. This board started as an lcd connector replacement to regain backlight because when old connector was tapped the backlight would go in and out. Tried known good working LCD. So I changed the connector and it seemed to work fine for a bit. Then backlight started going in and out. Now there is none at all.


F9800 is 12 V
PWM is 2.8 V
BKLT EN is .002 V (missing)
PPVIN is 4.93 V
R9731 .002 on pin 1

When I take measurements on pins 4 and 6 on Q9807, backlight starts to come through dim. Is this a grounding issue on Q9807? I have already replaced it.

Thanks in advance. Have a good one.
 
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RyanLEN

New member
I have 3.2 V on both 2 and 5 of Q9807. I have found that it wasn't me taking measurements on Q9807 that was causing the backlight circuit to activate, but from the pressure of the probes. So what is happening is when ever I flex the board from any point from CPU area left to the backlight area (The whole left side of the board with fans closest to me on table and LCD connector facing up) the backlight circuit becomes active. I don't believe it is the LCD connector because this is the second one I have tried. So obviously there is a fucked up trace/chip somewhere. But how the hell am I supposed to find it? Thanks again. Have a good one.
 
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RyanLEN

New member
Hi,Thanks. 2.8V both ways.Also, I lose BKLT_EN when its not working. (no pressure applied)
 
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RyanLEN

New member
Tapping U9600 definitely effects it backlight. But doesn't seem to anymore then flexing the rest of that side of the CPU. Maybe that's the week point and anywhere I put pressure on that side of CPU directly effects u9600? Thanks.
 

dukefawks

Administrator
Pretty sure it is U9600. Carefully remove all edge bonding and reflow first. If that fucks up have fun reballing it.
 
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