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HELP....Flatpanel Backlight no longer works.

K

Krypton

[H]F Junkie
Joined
Oct 11, 2004
Messages
11,221
Just wanting some advice here. The backlight on my wife's flatpanel montior went out. If you hold a flashlight to the screen, you can see the windows desktop faintly, just no backlight. The monitor is out of warranty, and it is only a 15 inch. I picked it up a few years ago used.

It is a Visiontek. Even though the brand is no longer around, I am sure all the components are standard stuff. Anyone know where I can order replacement back lights and such?

I am going to trouble shoot this thing tommorrow and see if there is an issue with any of the power supplying the backlight to be sure.


Any pointers would help if anyone else has had to do this before. I am very technical so ....
 
Typically it's either the backlight or the inverter. The inverter is what controls voltage to the backlight.

In almost every case, ever, it is not financially sound to repair a backlight on an LCD. The cost is, for whatever evil, greedy reason, several times the cost of a new monitor because most companies won't sell a replacement lamp. They will only sell a complete panel.

Example. The cost to have an IBM Thinkpad 14" display replaced (broken, etc...) out of warranty is over $800! This is not an unusual amount.

If you call any manufacturer and ask them (say, during a pre-sales call) how much it costs to repair a defective backlight out of warranty I defy you actually get an answer.

Backlights are the dirty-little-secret of the LCD industry.

-Larry


swetmore said:
Just wanting some advice here. The backlight on my wife's flatpanel montior went out. If you hold a flashlight to the screen, you can see the windows desktop faintly, just no backlight. The monitor is out of warranty, and it is only a 15 inch. I picked it up a few years ago used.

It is a Visiontek. Even though the brand is no longer around, I am sure all the components are standard stuff. Anyone know where I can order replacement back lights and such?

I am going to trouble shoot this thing tommorrow and see if there is an issue with any of the power supplying the backlight to be sure.


Any pointers would help if anyone else has had to do this before. I am very technical so ....
Click to expand...
 
Ok got the Focker apart. The back lighting it actually cold cathode lighting (says it on stickers). The whole panel assembly comes off in one piece. with a couple of power diconnects for the backlights (one for top, the other bottom).

With the display removed, I hooked up my ohm meter to one of the backlight power connecters and I am hardly getting any voltage (like .05v), so looks like the switching circuity / power supply issue.

I am going to test the external power supply to the monitor and see if that yields anything.


Thanks
 
Ok so I narrowed it down to my Power Inverter circuit board to the cold cathode back lighting being bad or not being switched on.

I found this web site and looks like anyone can fix their own lcd monitor backlighting for like $20! Very ingenious work around from the man trying to stick it to you.

http://www.inventgeek.com/Projects/shorts/Page1.aspx

I am going to look into this more soon, and report back how it works for me. This might be a good sticky.




WTF!!!!!!!!!! Typing this, all of a sudden the back light is working again???

EDIT (2/4/2006): The panel works with my laptop and not my full sized box. I tried a new video card, but to no avail. As soon as I go into Windows, it craps out. Even though I can see the text on the screen with a flashlight. On the laptop however, all seems ok.

Bizzare as this is, this all started when I forced formatting the second partition on my hard drive. I find this a bizzare conicidence.

Looks like a format and reinstall might be worth a try, but I will ghost the existing contents first. Maybe I will just try and older ghost image first.
 
If it went out once, it will again :(

Check the cable's, especially any thin-film cables. Oddly, they do go bad (especially on laptops where the flex at the hinge point).

-Larry
 
Nice find, I am sure these info will come in handy some time... On the subject of back lights. Is it better to turn the LCDs off or let it go into standby mode? I know the standby mode will use more power, but i wonder if it is actually better for the longevity of the LCD components...
 
H-street said:
there is only 1 thing to do with a 15" LCD with a burnt out backlight


http://www.denguru.com/2004/11/13/supersize_your_tv_for_/index.html
Click to expand...

That's a great idea.


Looks like Fry's is going to have everything I need. I am going to get a new cold cathode power inverter.

Replacement lights:

http://shop2.outpost.com/product/1343346

and 12v power supplly. I checked mine is getting 12v, just not working. I am going to pick on of these up at frys:

http://shop2.outpost.com/product/1343576

Update: The solution works well! Saved about 2-300 from not buying a new monitor for the wife, so I can spend it on my rig. :D
 
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