Sony KV- 20FV12 get no signal on screen. Same cable outlet works on other TV as a test. Cable ON in menu. Auto Set search produces search but still no signal.

I assume you have analog cable TV service and no cable box. Press MENU button on your TV remote. Go over to CHANNEL SETUP. There are four arrow buttons and a button in the middle of the arrow buttons on the TV remote control. Use these arrow buttons to go up, down, left and right. Use the button in the center to select. TV On-screen menu has Video, then Audio, then Channel Setup.

Cable can be set to ON or OFF, you want to set it ON to get cable channels.
Go down to AUTO PROGRAM and select it, press button in the center of arrow keys.
A short delay while available channels are searched so be patient. After Auto Program finishes, press MENU to exit. You can perform Auto Program whenever required.

You can also add or skip channels manually. You will discover more options in the TVs menus.

www.radioshack.com

just click this link for the required info

Try a hard reset.

It's likely that during your search you switched to an alternate input which has "no signal" accidentally. Open the menu and select the input that is associated with where your cable/cables is connected.

The owners manual for that model is available online for free! Go here and download or view the manual for your particular set. http://ec1.images-amazon.com/media/i3d/01/A/man-migrate/MANUAL000050375.pdf

I am sure that would be helpful for you in any case.

Yea, you need a new Q board.

Setting Up the TV
After you have finished connecting your TV, you can use Auto Program to set up your
channels. During Auto Program, the TV will automatically search for available channels and
program receivable channels.
(Make sure CABLE is connected on coaxial and you are not using any other connections such as cable box, hdtv or satellite antenna)

1 Press to turn on the TV. The Initial Setup screen appears.
2 Press on the remote control or on the TV front panel to start Auto Program, or press
to exit.
To perform Auto Program again
1 Press .
2 Press g to highlight Channel Menu.
3 Press f to highlight Cable. Press to select.
4 Press F or f to highlight On or Off according to how you connected your TV. Press to
select.
5 Press f to highlight Auto Program. Press to search for channels.
6 After Auto Program finishes, press to exit.
To reset the TV to factory settings
1 Turn the TV on.
2 Hold down on the remote control.
3 Press and release the POWER button on the TV front panel. The TV will turn itself off,
then back on.
4 Release .
✍ When you start Auto Program wait until it is finished; otherwise it will skip over channels that are
available. Perform Auto Program again to program receivable channels.
✍ The Initial Setup screen appears each time you turn on the TV until you perform Auto Program.
Initial Setup
Auto Program [CH+]
[CH–]
First please connect
cable/antenna
Exit

Check is RF Antena/ Cable connected? If yes, go to TV Menu and select Auto-Program. TV will start tuning and search all available channels on cable/ on-air. If there is no channel reception, TV has defective Tuner. If you know basic electronics knowledge, replace the Tuner or contact nearest Sony repair shop.

I have the same problem. Picture cuts out completely then back on. When I first turn it on, it does this constantly for about 15-20 mins, then about once every 30 mins or so. The sound is fine, but the picture just flashes on and off.

The color is also starting to shift a lot and cannot be fixed by adjusting COLOR-BRIGHTNESS-PICTURE in the video control menu system. Nothing seems to correct this. I've even unplugged the TV over night to see if it needed some sort of reset. Model = KV-20FV12. Purchased in 2004

My connection is a direct cable connection - Comcast cable. Same problem persist while showing a DVD as well.

There is a hidden setup on cable box.  Search manual on box.  I have the same TV with a Scientific Atlanta HD DVR.  If you turn off the cable box and hold the Guide + Info Buttons down, it will go into supported resolution setup.  My TV now goes to the appropriate resolution (480i, 720p or 1080i) what ever the channel is broadcasting.

Do you have another TV set you can test the cable with? It possible the TV you bought has a bad tuner. Or your cable line is dead.