No picture at all on my Bravia (4yrs old) but have sound, I suspect it's a problem with the backlight.

Check its back light inverter baord. There is no backlight. Check the reason for it. Check the voltages comes to backlight inverter board, for its power regulator board. For more information go to http://electronicshelponline.blogspot.com/

Main board problems

Sounds like you have a backlight problem. I would suggest turning on the set, dimming the lights in the room. Take a bright flashlight and shine it on the screen, do you see a faint picture?

oh, so that's your problem. I'm willing to bet you have a picture but just no backlight. Now does the screen come on briefly when you first turn the TV on? Or is the screen black at all times?? Turn on the TV, turn off the lights in the room. Take a very bright flash light and shine it one the screen.I bet you see a dim picture. It sounds like you have a backlight problem. Either you are missing 24VDC from the power supply, 3.3VDC "backlight on" signal from the main board, a bad inverter, or a bad backlamp.

could be the backlight or the inverter. the only way to tell for sure is to take the laptop apart and install a new inverter. although it really sounds like the backlight which is not cost effective to replace just the backlight, you're better off buying a new screen on ebay or something.

If you need further help, reach me via phone at https://www.6ya.com/expert/joel_63c670a84e9f6a97

Hi,
4 blinks indicated of backlight malfunction. The unit shutsdown to avoid overload to the inverter board.
Check the backlights, busted backlight has a physical indication of fault like blackened end, crack end. You must replaced the busted one and your unit will back to normal operation again.
Hope I helped you.
Have a nice day!
Thanks for using Fixya.

it sounds like your back light might be going out. You might be able to fix this by installing a new backlight inverter board.

Can you see a backlight on the screen? If not then there will be problem with the screen invertor.If there is a backlight then the problem will be the T- Con board..If the tv is brand new then you will get it repaired free under warranty if less than 1 year old. Hope this helps

Ur power IC invertder board it dead.
Need a new one.
Tries the Sony Website buy the power board.
MIght work or some things else might also burned.

It sounds like the backlight is going bad or possibly the panel. Let me see a picture of it. Talk to you later. Jay