RCA has been making televisions for decades, and numerous models exist. They range from older tube-box televisions to new flat screen LCD and projection TVs. When the sound on them goes out, each has different steps necessary to instigate repairs--most of which require a trained technician. Before you call one, however, you can take a few basic steps particular to all RCA televisions that may correct the sound problem.
Perform some basic troubleshooting steps that apply to all TVs. These include checking the "Mute" button to see if it has been pressed, examining the L/R balance to ensure sound is coming from both speakers and checking the cable connections to auxiliary components such as the stereo system (which controls external speakers).
Double-check the audio output jacks if you are using an S-video connection (a single round perforated jack) or component video connection (a trio of green, blue and red jacks). Those jacks only run the video signal to the RCA TV. In order to get an audio signal, you'll need to connect red and white RCA cables to their respective jacks on the TV.
Check the back of the TV for a switch labeled "Int/Ext." It controls the sound input on some RCA TVs. If you don't have any separate speakers, the switch should be set to "Int."
Activate the sound set-up feature by pushing the "Menu" button and scrolling to the sound bar. (This option can usually be found only on RCA flat-screen and projection screen TVs.) The sound bar allows you to set the sound from mono to stereo, activate the surround sound features, adjust the sound for headphone use, set volume levels and activate preset sound levels for movies, sports, concerts, video games and other specific sorts of programming. If any of these settings don't match the configuration of your home theater system, it may cause problems with the sound. If you're confused about the options, select any settings that read "Normal" or "Automatic." That should set the RCA TV to factory standard audio settings.
Press the "Menu" button and scroll to the "Set-Up" option, then go to "Preferences." You'll see a bar on the menu marked "Maximum Volume." You can use that to limit how loud the TV can get, which can cause problems if you don't know it's been set. Move the arrow on the bar to reset the maximum volume, then hold down the "OK" button on the remote to hear what that volume sounds like. You can then listen to the TV as normal.
Individual RCA TV types may have their own instructions about correcting the sound. Consult your owner's manual to see if any of them apply in your case.
When checking cable connections, always turn your RCA TV off, along with other components such as a DVD player. Turn them on again only after the cables are secure.