Looking for backlight strips for my philips model no. 40PFL3107H/12 AND INVERTER TO

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Lets start by eliminating the parts that won't cause your issue, the main board could not cause it, it turns the lamps off, that's correct it turns them off, the inverter will turn the lamps on with the main board not connected. The power board could cause it but it's not probable, only way this could happen would be some shorted windings in the transformer that powers the backlights and in the thousands of?? set's we've repaired in our shop I've only seen excessive backlight voltage a couple times. Considering this set is edge-lite, the lamps get quite warm, if a few are shorted the strip will get hot enough to melt the plexiglass. Where are you getting the replacement lamps from? Is it possible they're not meant for the model set you have? Are you getting a good contact with the tape on the back of the strips? They need to be tight against the frame, is there tape that's bunched up causing a gap between the strips and frame? Without pulling up service lit on the TV (not at shop now) I can't tell you what the correct B+ voltage should be coming out of the inverter but usually it's about 80% of the DC rating of the caps. Other than what I've suggested I can' think of anything else to advise on, I can get the exact voltage of the inverter next week when I get into work.

The next step would be to check the inverter board. This board is responsible for supplying the power to the backlight. If the inverter board is defective, it will need to be replaced. If the inverter board is not the issue, then the issue may be with the mainboard.

The Vizio "E" (economy) series sets have local diming, on most brands if some of the lamps go bad the screen is black but not on these model Vizio TV's, for this reason it's harder to troubleshoot the set for possible bad backlights or backlight inverter issues. If you have a LED backlight tester you can test each zone at the backlight connector off the inverter board to see if each is working, without a tester you're going to need to remove the panel then move strips that don't light to ones that do and see if it's the strips bad or inverter issues.

most likely the problem is if your lg tv is between 40 and 50 inches that the internal LEDS have gone bad typical with LG models you need to replace the LED light strips inside the panel and it is not easy to do unless your experienced with this take it to a shop or see the link below for more info LG 39 LED TV Model 39LN No Backlights Bad LEDs How To Replace LED Strips

The backlight inverter is built into the power supply of this unit. When it fades to black screen, do you see any backlight at all?
If you do see some light, you have a 'blank screen' problem and the backlight is not the cause. Since you can still hear sound and can control the tv otherwise, the problem is likely in the TCON board.
If there is no light coming out, perform a flashlight test (search YouTube for details on this). If you pass the flashlight test, then try replacing the power supply board.

Providing it is backlit and not oled or other The inverters hold the backlight in each and can be obtained via eBay for most make and models.best to put the screen on a folded blanket on the floor before attempting to remove back.make sure the power is off and that you don't touch internals.then inspect each invertor count the number for the screen best to replace all together or you will get uneven illumination.

There are only two boards. Master - 6632L-0470A REV 1.3 and Slave - 6632L-0471A Rev 1.3

Verify that you do have 12~18vdc feeding the backlight inverter board. Look inside the TV for burnt parts, bad capacitors, etc.
http://en.wikipedia.org/wiki/Capacitor_plague

If the screen is black: Check the backlight circuit, bulb and inverter.

If the inverter and backlight is OK: look at the electrolytic capacitors (round aluminium "cans" with X's or K's on top) if there are any that look "domed up" (swelled), replace.

You've now covered 90%+ of possibilties.

GL!