I need to see a main board for my Phillips LCD tv Model # 40PFL3705D/F7

do you have any sound,if you do,press the menu button and with a flashight point it at the tv and see if u see any type of image or turn the light off and look in the back to see if u have any backlight

Sounds like white balance adjustment mistuned. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/
Faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.

Back - light problem. 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.
Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window " to get gathered related posts.

Fault to its main board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/ . In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

Here's how you determine if it's the T-Con board. Turn the TV on and shine a flashlight on the screen. If you can see the program you're hearing then the T-Con board is OK. The inverter board controls the back lights. This board is the problem.

There are 2 posiblities 1. T-con board is bad needs replaced. 2. Back lights have gone bad take a flash light to the screen in an angle and see if you see any picture? if so back lights are gone they can be replaced.

Sounds like T'Con board fault. Contact the authorized service center for Philips. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" or "Magazine" will make surf easy. Pull up older posts. Surf the site with patience. Do a search by type in the brand name of your device at its search box.
http://electronicshelponline.blogspot.com/

I once had a problem with a Phillips tv.It was less than one year old and one day ,all of a suddenm a black screen came up.I elarned it was called the "black screen of death" and that other people had gone through the same thing.Someone online had actually written to Phillips and they had gotten a new TV form them,so I tried the same thing and amazingly,Phillips gave us a new TV and came and took the old one.The enw worked fine. So you may have a lemon on your hands.Unfortunately, I do not have the letter I sent to them but the replacement they sent me was part of their "Rapid Replacement" program.This wa sin 2008 so I'm not sure if they still ahve it but it may be worth a try.

looking online as i have same problem, sound without picture points to T CON board. approx $50-100 part + labor

The LCD controller (T-Con board) or main board needs to be replace to fix the no video failure.
Check this link to find parts for your LCD.