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 Post subject: Laptop screen backlights but no image - not even BIOS image
 Post Posted: Sat Dec 29, 2012 5:32 pm 
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Joined: Thu May 31, 2007 8:37 pm
Posts: 200
Location: St. Louis, MO
Hello. I was recently using my laptop, and in a brief "flash" the image disappeared, leaving behind only the backlight and a dim grey looking view on the screen.

Rebooting didn't help. Connecting an external display to the laptop gives a normal view of everything, including BIOS functions.

I disassembled the laptop, down to the display, (I have not removed the LCD to check the rear of the display yet, although I don't see how the LCD cable could come loose from there) and the LCD cable to the motherboard is snug, and nothing looks amiss.

Another website suggested a reflow might be necessary, but, would an external monitor function if a video chip reflow was necessary?

Please give me some suggestions as to what I can do to fix my laptop. Thanks!

HP Pavilion dv7-3065dx Entertainment Notebook PC

http://h10025.www1.hp.com/ewfrf/wc/prod ... g=en&cc=us

Thanks in advance.


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Sat Dec 29, 2012 5:43 pm 
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If the system functions properly with an external display then that would suggest that the problem is limited to the internal display and not the GPU or video circuitry on the motherboard. If the internal display is dark but you can see the display functioning by shining a bright flashlight on it, then that would mean either the inverter or lamp have failed. In most cases replacing the inverter is relatively inexpensive, while replacing the lamp may be difficult or even impossible.

If it isn't the inverter and/or the display shows no sign of functioning then the problem could be either the internal cable connection or the display itself. I would carefully inspect the cable, try removing and reconnecting it, and possibly wiggling it to see if it has an intermittent break. If you suspect the cable is bad then I would try replacing it, otherwise that pretty much leaves the actual display as the culprit. At that point you'll have to decide whether such a replacement is worthwhile (you may find a used one cheap on eBay). Another option is to repurpose the system as a desktop (external display) or home server (no display necessary except during initial setup). Let me know how things turn out, Scott.


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Sat Dec 29, 2012 5:56 pm 
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Joined: Thu May 31, 2007 8:37 pm
Posts: 200
Location: St. Louis, MO
That's actually just opposite.

There is a bright light coming from the screen.....


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Sat Dec 29, 2012 6:21 pm 
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Joined: Tue May 08, 2007 8:54 pm
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Here ya go.


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Sat Dec 29, 2012 6:28 pm 
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I see that display has an LED backlight (no inverter would be used) and the backlight seems to be working. That leaves the cable, display, and possibly the motherboard. Unfortunately the only way to know whether it's the cable or display itself is to replace them. And because the internal display connects to a different set of signals than the external display, there is a slight chance that the defect could be on the motherboard, meaning the cable and display may be fine.

Another option would be to part it out on eBay and purchase a ThinkPad instead. Scott.


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Sat Dec 29, 2012 11:45 pm 
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Joined: Thu May 31, 2007 8:37 pm
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Location: St. Louis, MO
Thankfully, this situation has been resolved, $0.00.

I finished taking the laptop apart, and started with the least expensive part. I made sure the display end of the cable was firmly seated to the LCD. Even though there is no appreciable reason (other than thermal expansion and contraction) that would make it unseat in the least, and the tape they are usually secured with is supposed to help with that.

In any matter, after doing this, I can now see this on my screen:

Thanks so much, once again, Scott! You are awesome, as is this site!


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Sat Dec 29, 2012 11:50 pm 
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Excellent! I'm glad it all worked out, and thanks for letting me know the outcome. Scott.


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Sun Dec 30, 2012 10:42 pm 
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Location: St. Louis, MO
Hello.

I have ONE more issue! At one point when I was doing the work on this laptop, this little bar magnet "flew" out from some spot and stuck to my screwdriver!

I knew it happened, and I am fairly certain this didn't happen until I popped the bezel apart from the LCD, however, when I closely examined that area where I thought I saw it come from, I didn't see any area that might have "held" a magnet.

If I close my lid now, nothing happens. I have found a "sweet spot" where I can sit the magnet on top of the display hinge where the laptop will "sleep" like it should.

Does this magnet belong INSIDE the screen? Any way to FIND exactly WHERE? I have not been able to find a "tech" manual to see.

Thanks again!


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Mon Dec 31, 2012 12:57 am 
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That is a magnet which activates a switch indicating to the system that the lid is closed. You'll need to glue it back into place opposite the switch on the other side. If the switch is in the base then the magnet would go in the screen and vice versa. Unfortunately since HP doesn't publish service manuals you'll have to figure out the location for yourself. Having access to factory service manuals is another one of the many reasons that I use ThinkPads exclusively. Scott.


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Mon Dec 31, 2012 2:49 pm 
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Joined: Thu May 31, 2007 8:37 pm
Posts: 200
Location: St. Louis, MO
Thanks very much for the advice. I was actually able to find a teardown service manual:

http://h10025.www1.hp.com/ewfrf/wc/manu ... t=4041777&

However, even in the directions relating to LCD R/R, and touch panel R/R, and down to system board R/R, no mention whatsoever is made of this little magnet.

I'm a Dell Technician, and Dell usually mentions things like this in their service manuals.

This magnet literally "flew" away from it's resting spot and stuck to my screwdriver when I was working on the laptop, giving NO indication where it belonged!

Thanks for the advice.....


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Mon Dec 31, 2012 3:19 pm 
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Quote:
I was actually able to find a teardown service manual:...

I see they do indeed provide a manual for that system, which is excellent. Unfortunately as you say it does not show anything about the magnet. It was most likely glued in somewhere around the perimeter. Maybe try looking for some residue that might indicate the original location. You could also try running the magnet around on top of the base with the system running. As soon as the magnet is placed over the right location the system should think that the lid is closed and go into Sleep mode. Scott.


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 Post subject: Re: Laptop screen backlights but no image - not even BIOS im
 Post Posted: Mon Dec 31, 2012 4:01 pm 
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Joined: Thu Jan 15, 2009 1:27 pm
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Location: Stowmarket, Suffolk England
Last time I had a magnet like that there was a small cut out in the LCD surround the same size as the Magnet.

Heard a story about the Dell magnets Laptops' where stacking them caused the sensors to fail, ruining most of that stack of them!


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