I have a blank screen, with sound. From the right angle you can make out a faint picture. Tried messing with screen muting, auto lighting, etc. I replaced the main video board. Same problem remains.

SOURCE: Vizio 42 in L42HDTV10A no power no lights no nothing

You can look at the various module failure symptoms and service / replacement options for the L42HDTV10A here:
http://www.coppelltvrepair.com/search?Q=l42hdtv10a&As=false&Pf=&Pt=&Sid=false&btnsearch=Search

SOURCE: No imaging, have sound, backlight, etc.

It may be an input cable problem. Check hdmi and or coax cables to make sure they are not damaged . If you have another tv hook cables up to it to make sure they are working. Hope this helps.

The Knight

• 76851 Answers
• Posted on Dec 09, 2014

SOURCE: I have a LG M2262DL LCD TV/Monitor. When I switch it on I initially have a picture and sound. Usually within seconds the screen goes blank but the sound is good.

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/

SOURCE: Vizio TV model # E321VA turns on and after approx. 5 seconds screen goes black and backlight remains on?

In my whole career as a tech, I never had a defect on a place I would have wanted it. And believe me, if an integrated circuit is defect, or even a diode, you won't see it on the outside of the component. Most of the time you need more than just a multimeter. Any way, to use it, you at least should have a diagram pointing out what voltages you should measure on what point. If not it is pointless.
Be aware even the 120 volt AC, can be deadly, so don't play around with that voltage.

The Knight

• 76851 Answers
• Posted on Feb 10, 2017

SOURCE: 2nd try see last sentences....lg led 32ln5310 tv, sound but no picture, no backlights, nothing visible on flashlight test, what should I replace? Main board, T-Con Board, Power Supply board or Leds

The main power supply regulator section circuit fault. Either it will be a separate board, or the part of main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/ It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.
Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window of the Homepage" to get gathered related posts.