Some older televisions only have coaxial inputs, but most audio/video devices need component (the red, white and yellow cables) inputs. Instead of upgrading your television, use an RF modulator, a small device that usually costs under $30, to convert your component cables to coaxial outputs. They are easy to use and are compatible with any device that has a component output.
You should be able to find an RF modulator at any store that sells television and other audio/video equipment. To connect the RF modulator, you'll need a coaxial cable and a component cable. If the device you are connecting is more than three feet away from the television, purchase a longer coaxial cable. The signal will be degraded if you use a longer component cable, so always use the shortest one possible (preferably less than two feet).
If the coaxial connector on your television is used by another device (such as a satellite receiver or a VCR), purchase a coaxial switch box. This will allow you to connect multiple coaxial devices to a single connector. The box has several buttons on the front, which control which device is currently in use. Some retailers sell combination RF modulator/switches.
Plug in the coaxial cable to the signal "out" jack on the back of the RF modulator. There will only be one coaxial jack. Likewise, plug the component cable ends into the matching colors. Again, there will be only one jack for each color.
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Connect the other end of the coaxial cable to your television's "in" jack. This may be labeled "aux in", "ant in" or "a/v in". If you're using a switch box, connect the cable to any of the inputs.
Plug the other ends of the component cables into the device. Most devices only have "out" jacks, but, if there are multiple connectors, look for the red, white and yellow set labeled "a/v out".
Turn your television to channel 3 or 4. The channel varies between RF modulators, although some allow you to set the channel used, via a small switch on the back. Once you have your television on the correct channel, turn on the audio/video device and use it as normal.
If the device isn't working, go through a few basic troubleshooting steps. Ensure the RF modulator is plugged in and receiving power. Double check the cable connectors. Each should be tight fitting and not wobble or move in the jack on the RF modulator, television or device. Verify that each component connector is plugged in to the right jack. Finally, make sure the television is set to the channel the RF modulator is using.