I really want to know if I can use a 9 volt battery to test three lcd/led backlights at a time.Thanks in advance.

There are a lot of things that could be causing the backlight issue you're seeing. First thing to look at is the 7 caps that sit next to the 24 volt backlight supply plug, those have been known to give issues but going by how this set has acted in the past I don't think this is your issue but check it first. If the caps look good measure the 24 volt supply that goes to the LED driver, make sure you see correct voltage there, next thing I'd look at is the LED driver board, be sure there aren't any burned spots on that board, next test is going to be the individual rails going to the LED strips and see if you see voltage there, if you don't replace the driver, if you do it has to be backlights but generally only some will fail like you were seeing to start with, with some dark areas on the screen

Hi Kol, I would suggest checking all of the connections that you've disconnected to install the new LED strips. The LEDs are connected in series and it wouldn't make a difference if you installed them in a certain order. If after checking all the connections the TV still doesn't work then it might be a possibility that the new LEDs might be DOA. You can test the LEDs strips using a 9 volts battery and a couple of alligator clips. Test the LEDs one strip at a time.
Hope this helps.

Make sure the power supply is being triggered. If there is no LED_On signal it may read that. But if you know the backlight should be in, then check LEDs. Try powering each LED on the strip individually with a battery/resistor. unhook each strip before testing.

Two AA batteries are 3 volts (1.5v per battery). A 9 v battery is 9 volts. You are going to burn out your LED lights.

Semper Fi,
Z

Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis. http://electronicshelponline.blogspot.com/ To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.

Perhaps the backlight LED driver board needs to re-seated.
Also check flex wire connectors for loose connection.
reseat or replace

yes the led backlight for whatever reason is not functioning and that is the root cause of your problem. Unfortunately to find a replacement led backlight is tough as the backlight is normally fixed with the lcd panel and has to match the voltage and all that stuff with motherboard. and if that doesn't match you might short the tv itself. this case is as good as getting a replacement lcd panel.

1) Wrong LCD screen

2) Video Cable (LCD Cable) is not connected tightly.
Motherboard side, or LCD screen side; or both.

3) IF, a screen Inverter is used, the small cable from the Video Cable, that connects to the screen Inverter; is not connected, or has a loose connection to it. (screen Inverter)

4) An LCD screen, and a screen Inverter are a Matched unit.
If it's the wrong LCD screen......................?

5) IF, a screen Inverter is used; the diagnosis was wrong, and the LCD screen was replaced.
90 PERCENT of the time, the fault is a bad screen Inverter.

A) Laptop's LCD screen uses a CCFL, (Or more than one), for a Backlight; the laptop uses a screen Inverter.

Diagnostic flowchart leads from Graphics Chipset, to Video Cable, to screen Inverter, THEN, LCD screen.
Expensive LCD screen was replaced, instead of the actual part that needed replacing;
Video Cable: $9 to $22
Screen Inverter: $9 to $22

LCD screen: $60 to $245

B) Laptop's LCD screen uses LED backlighting, and does NOT use a screen Inverter:

Diagnostic flowchart is;
A) Video Cable;
A Video Cable should have it's connections PHYSICALLY checked.
You have to try to push the connectors in tighter.
Visual inspection alone will NOT do.

Making sure the Video Cable connections are tight, and this does not fix the problem, then the Video Cable needs to be removed; and every wire in the Video Cable checked for Continuity with a multimeter set to OHM's. (1K)

Not feasible, then take the Video Cable down to the nearest small computer shop; and have the resident tech check it for Continuity.
Should only be a few bucks.

Or just replace the Video Cable.
(Parts changing I know, but...........?)

Primer:
An LCD screen cannot produce light. It needs an additional light source.
A Backlight is the additional light source.

A Backlight can be a CCFL, (Or more than one), or a series of LED's.
(Light Emitting Diode)

A CCFL is a Cold Cathode Fluorescent Lamp. (Bulb)
Similar to Fluorescent lighting used in homes, and businesses; but on a MUCH smaller scale.

Average thickness is 2mm. That is a little large than 1/16th of an Inch.
Average thickness is almost as long, as the LCD screen is in height.
View the last 8 photos,

http://www.laptoprepair101.com/laptop/2007/12/09/replace-laptop-backlight-ccfl-lamp/

A screen Inverter is used to convert the power, (Electricity), from the laptop; for the LCD screen, and Backlight.

As previously stated, Backlighting that uses CCFL, uses a screen Inverter.
LED backlighting MAY, or MAY NOT use a screen Inverter.
When the LED backlight technology first came out, it seems some did use a screen Inverter.
It also seems as the technology advanced, LED backlighting does Not use a screen Inverter.

Regards,
joecoolvette

Most likely not a battery problem. Since the battery is fairly new, a good charge should restore it. As far as the corrosion, A thorough cleaning of the battery cables should suffice and replacement shouldn't be necessary.

I'm having the same problem and it turns out to be the main board.This Service guide is for Version 1.0 but turned out to be helpful
http://www.abcelectronique.com/forum/attachment.php?attachmentid=12292