Solved

Backlight shorts in and out

Posted on 2008-06-18
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Last Modified: 2013-11-09
Hello,

 

I am working on a Dell D505 laptop. The display is dark when operating.  When I put pressure on a small area near the power button the display will come to life with the normal backlight display.  I have noticed when I put apply some light pressure on the left side of the power buton PCB (pushing it ever so slightly to the left) I will get the full normal display otherwise I get just a dark display.  I have taken the laptop completely apart and cleaned underneath the motherboard.  I have not noticed anything unusual that would be causing a short. What could be causing this problem? I appreciate any and all help with this problem.
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Question by:compucharley
7 Comments
 
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Assisted Solution

by:Sh4d1
Sh4d1 earned 150 total points
ID: 21813218
I had this problem on one LCD. It is due to detached cables from board. You can only complain this or put it to servis. They need to cables to right place on board or change board.
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Author Comment

by:compucharley
ID: 21814581
I have checked the cable to t he board they seem ok as far as being connected.
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LVL 27

Expert Comment

by:David-Howard
ID: 21816430
I read a bit on your issue and I found multiple sites that state it could be the laptop inverter.
The inverter is normally located at the bottom of the LCD itself and not under the motherboard. This would explain why you didn't locate any loose cables (If it's the inverter.)
The first link states the probable cause along with screen shots.
http://www.laptoprepair101.com/laptop/2007/01/31/replace-screen-inverter-fix-backlight/comment-page-8/
http://www.laptoprepair.co.uk/laptop-backlight-problem-dim-screen.html
David
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Author Comment

by:compucharley
ID: 21816469
I tried a good known display that would eleiminate the the inverter and backlight and got the same results.  It is some underneath the motherboard i suppose tha the short  must be.
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LVL 91

Assisted Solution

by:nobus
nobus earned 150 total points
ID: 21819839
>>  I have checked the cable to t he board they seem ok as far as being connected.  <<   did you remove and reseat it?   if not, try that, and inspect it closely.
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LVL 27

Accepted Solution

by:
David-Howard earned 200 total points
ID: 21834157
Yes, you have most definitely narrowed it down using your monitor troubleshooting method.
The service manual can be found here for your D505.
http://nokomis.k12.il.us/unit-office/technology/downloads/sm.exe/view
(As usual, please take precautions when downloading and scan the file prior to opening.)
David
0
 

Author Comment

by:compucharley
ID: 21835505
Hello,

There is a long bracket just to the right of the small power button PCB.  I noticed when applying about 2lbs of  pressure to this bracket the display would be in a stable/normal state without the pressure the dispaly goes dark.  What I did to repair the problerm was I got a small piece of 1" x 2" piece of plastic and I marked holes to drill my screw holes and pin pointed where the short was most sensitive and glued  two 1/2"x1x2" pieces to my 1" x 2" where I wanted the most pressure to be applied and then there was a screww hole near the corner of the CD-ROM caddy I screwed the opposite end of the 1" x 2" to this screw hole to ancor my little plastic plate and my efforts paid off where ever the ground out was it was eliminated with my fix. I litterally tore the whole laptop apart to see where the short might be and could not find anything that was suspect. Thank you everybody for your help.
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