HP G71-340US LAPTOP has no video

I have an "HP G71-340US" LAPTOP that displays no video
- when I power on the laptop I can see a faint image in the background. Basically I can see the images but without the background light.
- If I attach a monitor to the laptop, it displays perfectly fine on the monitor. So that tells me that there's nothing wrong with the video controller

My question is
- do I have a bad screen, or the bulb is bad inside the screen or do I need a new inverter?
- I can purchase a new screen for around $75-$85 online. But I'd hate to do that if its not the screen. I assume most people don't replace bulb,  they just purchase the entire screen which contains the bulb.

I guess the answer I'm looking for is to determine what the most common fix for this issue and what most likely needs to be replaced

any help would be appreciated
Andreas GieryicComputer Networking, OwnerAsked:
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JohnBusiness Consultant (Owner)Commented:
The backlight (cold cathode tube) or inverter supply has failed. If all of this is in the lid (like a lot of Lenovo machines) the easy repair is to replace the lid.  That gets both parts and a new screen.

A failure in either part can give similar symptoms so it is not really feasible to say from here which part.

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Andreas GieryicComputer Networking, OwnerAuthor Commented:
Prior to posting this issue, I searched the database but found nothing similar to my issue. I've seen this on dozens of different laptops where the screen is blank but you can see an image faintly on the screen. And on those same laptops, the image is perfectly fine when attached to a VGA monitor. However almost all of those laptops were very old and not worth repairing.
Joshua GrantomSenior Systems AdministratorCommented:
John is dead-on.

I had that happen to me an one of my older HP laptops. Had to replace the inverter, then it worked like a charm.
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JohnBusiness Consultant (Owner)Commented:
The screen is likely OK (because you can see an image). If the inverter is good and the tube fails or the other way around, you get what you see.

I have purchased lids on eBay and been happy to keep a decent machine another year. On the other hand, if the machine is old enough, then maybe it is time for a new machine.
Trish GleesManaged IT SolutionsCommented:
John is correct, it is easier to replace the entire lid.
the easiest method for testing the inverter is another backligh lamp :  http://www.laptoprepair101.com/how-test-lcd-screen-inverter-in-laptop/
you can make a test setup :  http://ronelex.com/easy-testing-laptop-backlightccfl-inverter/146/

a nice article on testing inverter :  http://www.fonerbooks.com/test.htm

or - if you have a multimeter that can measure HF, like the fluke  Fluke 289 True RMS, you can just measure it :

***if you can't use any of the above, start by buying/replacing the inverter - much easier, and lower cost
Andreas GieryicComputer Networking, OwnerAuthor Commented:
I found this link

replacing the entire lid appears to be more costly than the screen and inverter together.
I'll delivered more research including the links provided
do you have a question?
Andreas GieryicComputer Networking, OwnerAuthor Commented:
Thanks for all users input. Very helpful.
JohnBusiness Consultant (Owner)Commented:
@agieryic  - Thank you and I was happy to help.
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