There is no picture and no sound but the volume

New 48" TCL tv. Hooked into cable box via hdmi cable from hdmi 2 per instructions. Problem is no sound. Screen looks great volume bar shows volume etc. Any ideas before I take it back to SAMs.

If you are using a cable box, there should be a setting to change your "aspect ratio". Some offer options such as fit to screen, zoom, wide, etc. see if you can change this setting from the remote. Without knowing what model cable box you have I acn't get more qpecific, but try this first.

If you are using a DTV coverter box, you may have changed the aspect ratio with your remote control. look for a button marked "aspect" or "picture size" use that to change size.
If you have a cable box, you may have a similar button.
Or you may find a picture size adjustment on your TV remote.
If you do not have "aspect" button on your remote try going to set up menu and look for picture size.
Older TVs used to have a vertical size adjustment at the back. look in the manual.
If none of the above, you have a biiger problem with the TV internal parts needing attention

can you see any any menus or the volume bar or channel indicator?
Make sure all your audio and video cables are hooked up correctly to inputs on the TV and to the same set of hookups. For example all of the VCR cables hooked into video 1 and all of the DVD cables in video 2.
Also check that you haven't hooked up the video to the tv's output. Some sets output audio and/or video for external devices such as recording setups or home theater sound systems.

Components in Power supply are bad most likely a 35v 100ufd capacitor if not then your Flyback transformer is bad

They volume indicator you are seeing is meant to show the volume of content if it were to be recorded on the cable's dvr. This indicator has no effect on the volume of content as it is being watched. This feature allows recording of sound at a set volume even while the tv is off. It sounds as though you'll just have to use the volume buttons on your tv's remote, though you might want to try seeing if there is alternative set-up for those cable volume buttons.

Be sure that your TV is set to channel 3 or 4 if you are using the RF cable or Video 1, etc if using the Audio/Video cable.  The Installation  Guide should appear.  The "improved" picture that you are seeing is simply the analog throughput, not the digital conversion.

If the television is connected to a cable box such as Time Warner's HD box, the picture mode can be changed by pressing the '#' on the cable box's remote keypad (where the channel numbers are). This cycles the picture between zoom, normal, and stretch which could be cause of your problem.

It sounds Like you Had Horz Failure In your Set,The Squealing you Heard was Probly the Horz Output Transistor,You will Probley have to take it to a Shop

I'd say just get a stereo system (amplifier) or something like that, and hook your cable box, vcr, converter or whatever you have right into that. That's what I've been doing for years. Most cable boxes and satellite boxes will control the main volume that goes to the sound output, or you can get a digital stereo with a remote to control the volume that way.