Backlights gone on LCD. Can I use LED?

[mikee55]

Hello, my LCD has no backlights, but the display works all be it black. Could one use a row of LEDS instead? Obviously I would use white ultra bright ones.

Or am I damn silly???



Mike

[poynton]

It depends on what the original lighting was.

New electroluminescent strips are available (some where in Germany)
It may also be the HV psu for the above.

Otherwise why not leds?

Andy

[mikee55]

Its the usual Cold Cathode Flouresent, except it had Four of them. Two at the bottom, two at the top.

I don't know how to test them, or the powersupply. The 12v Power module that came with the monitor has also failed. The display does work though. I've ran it off the Molex connector of my PC's power Supply and you can see an image. I figured 6 bright LEDS at the bottom and another 6 at the top. I could assemble them inside the narrow reflector strips that the CCFL's reside in, and ran the whole lot of a new power supply.


Cheers Mike

[rcavictim]

I have a NAD CD player, good old single play front load with analog power supplies inside (good, no switchmode noise generating junk!). It had a burnt cartridge fuse type lamp behind the backlit LCD display which is why I got the unit, otherwise mint and working perfectly for free at the dump. I replaced it with two small peanut lamps. The room has to be dark to see the orange/red display. I am not pleased. I think I'll go in and put a row of 5 bright white LED's in there. I expect to have to rig a series R and possibly diode. If there is an interference pattern from the display scan rate beating with the power if 60Hz I will further add a filter electrolytic across the LED bank.

[digitalstore]

Originally posted by mikee55
Hello, my LCD has no backlights, but the display works all be it black. Could one use a row of LEDS instead? Obviously I would use white ultra bright ones.

Or am I damn silly???



Mike

What are u trying to say? I could not understand.

[sdubb123]

but of course you can

http://hackedgadgets.com/2007/02/18/...ed-conversion/

[sheldonstv]

ok basically the answer is no......in order to test yr backlights you can use a backlight tester-the zippy is one i use-or as i have done is build a simple invertor to test the lamps.....leds will be totally useless..........first off you should check the 24v supply is present from the smps....pull the supply lead from the invertor and check the 24v is present if not repair the smps-if it is present look at the invertor....
common failures i have come across have been due to some sm parts failing but mostly invertor transformers failing....if you have no experience of repairing this sort of panel leave it alone and get some one to repair it for you....or get a replacement panel.
do not dissassemble the backlight assy if you have no repair experience-the ccfl lamps do fail sometimes but it is a bit involved if one or more needs replacement.

[Andrew Eckhardt]

Here's the gig in a nutshell. LEDs are being used for backlights now but if you care much about the color performance of your monitor you'll have to do a number of things carefully other than a little soldering. It will likely be more work than fixing the CCFL backlight.

Fluorescent tubes pretty much don't suddenly fail unless they get a leak or the ballast fails first. If you went through a long process of progressively reduced brightness the tubes are probably shot, otherwise you might want to look into repairing the ballast. You might want to look into that anyway.

[DigitalJunkie]

One problem I've come across a few times with LCD backlights is a small fuse on the inverter board..It's not the main fuse(s) for the power,but a smaller one used on a control/enable line.

[sheldonstv]

on this model there are 2 fuses present on the board i think... depends on the invertor pcb fitted ....one or the other can fail due to aging but usually the fault of no invertor backlight operation if the fuses has failed may be in the invertor drive side-which means surface mount parts which need replacement-if you dont have the necessary experience or tools to repair a double sided plated thro board of this type replacement pcbs are available-also the transformers on the pcb-one or more may be faulty but again the pcb can be scrapped if these items are not properly removed from the board.....also why are we bothering with replying to this post????i seen after i replied the date of the original post....2008