Toshiba Regza 32HL67 after about an hour the screen goes to black. I still have sound. I turn off and on the TV and picture comes back. This happened recently once before.... the difference between now and then, is that now, an hour or so after doing this the first time tonight, it did it again. Is this a lamp problem (I have reading about other people's issues) or is this something else?.

SOURCE: Sharp aquos lcd screen goes blank

i was having these same problems with the screen going black, and i found that when i hit the back of my tv it would work sometimes. so, i improvised on some of the advice on this page and so far no problems. here is what i did (its very easy):

1. lay the tv on the floor and take off the back panel. (i think 12 screws)

2. on the right side of the tv (as you are looking at the back) you will notice a large metal covering that is held in place by 6 screws. unscrew these and remove the metal cover.

3. you will notice that the three screw holes on the left side of the board have some sort of metal or solder around them, in sort of a star pattern. when i looked closely i noticed that most of the metal (solder) was tarnished, or kind of blackened. (this must mean that the ground screws werent getting a good connection and this would explain why it would work sometimes when i hit it because it would vibrate the screws enough to get a good connection! )

so, take a pencil eraser and erase all the black or tarnish off the metal surrounding the screw holes. thats it! (to be safe i took some sandpaper and cleaned up the screw holes on the back of the metal covering, but i dont know if that was necessary)

at this point i followed another gentleman's advice to do a hard reset. this involved unplugging the 8 connections although i dont know if this was really necessary because i believe my problem was a ground issue. i did it just to be safe. his advice is on this site if you want to do this step.

4. i put everything back together and it worked! i performed a soft reset at this point which puts your tv back to factory settings. just go to menu>setup>reset>return to factory settings? yes
this will turn your tv off and back on. that's it. so far so good for me.

SOURCE: samsung tv turning off by itself

I had a similar problem where my 61" Samsung DLP was turning itself off very frequently I had resolved to try replacing the bulb. I called a local TV repair place to see if they had my buld in stock. The guy I spoke to actually told me how to fix my problem! There is a little blue switch behind the bulb access door. The inside of the door has a little piece that presses the switch down. The switch is supposed to work correctly weather the switch is in the up or down position but samsung forgot to take expansion from heat into account. If the switch is held in the upper position by the door and the plastic expands to a certain point, it triggers the set to shut off. This does not occur of the switch is held in the lower position. What you need to do is take the access door off and put it back on by sliding it into position from above. That will hold the switch in the down position, eliminating the problem. My set has not **** itself off ever since.

SOURCE: LG 42LG5 TURN ON TV PICTURE GOES BLACK

This could be 1 of a few things here. Without opening up your set and trying to look at voltages or indiciator lights I couldn't tell you exactly without some more info.

Without looking at it myself here are my thoughts and where I would first look at.

It may be a main board because:
1) Main board processes all your audio/video signals. Bad main board means bad video processing. Could do that. Especially if the main board is not sending the right signal or a bad signal to the rest of the boards so they don't do their jobs. 

It may be a power supply because:
1) Power supply is well, the power supply. If it's sending inadaquete voltage to the main board you may not be recieving enough juice to keep that main board doing your video processing or further up the line keeping enough juice flowing to your TCon board to keep it telling things where to go and what to do. The power supply sends voltages to your Ballast board(controls your lights) and to your main board through which power is supplied to your TCon board via a LVDS line and a +12/+16V signals. If the power supply isn't pumping out enough juice to keep the TCon or Main Board running, it could be a problem. By the same token it could be that your P/S isn't sending power out to your ballast board. 

It could be a TCon because:
1) If the TCon is bad, you won't get your pictures. This could be the TCon board itself or the LVDS cable from your TCon to your Main. However, with few exceptions, if it's a bad TCon you're looking at a total panel replacement. 

It could be a ballast board because:
1) The Ballast Board controls the lighting behind the LCD screen. If this isn't working right you won't be seeing much of anything without that back lighting. If this is bad, it's a panel replacement. These are not field replaceable items by LG. 

Based on the symptoms, without more data or a eyes-on view of it, I would say you're most likely looking at a Main Brd or PSU problem. 

SOURCE: Picture goes black but hear the sound

this is the problem related to display of ur TV screen...please contact the service centre...plz dont try to repair it urself..

SOURCE: Screen lower half goes black/blank

The lower "Y Buffer" board is defective. Best repaired by a technician, or contact Phillips support for the part if you think you are able to replace a small circuit board on your own.