What Kind of Cables Do I Have?
These are not a silly questions, especially if someone else hooked it up for you. Knowing how your TV is connected to other devices might help you troubleshoot certain problems. Let’s first look at the different kinds of cables you may have. Below is a description of the possible cables that can be used.
What is an HDMI Cable?
HDMI cables are designed for connecting video devices to TVs. The connectors on either end have a trapezoidal shape. These cables carry digital video, digital audio and control data signals.
DVI connectors look the same as HDMI connectors. The same type of cable is used for DVI and HDMI connections. The difference is the kind of signal each of them carries. The DVI signal does not carry any audio. That’s why if you need to have a DVI connection, audio cables with red and white phono (RCA) plugs will need to accompany the DVI cable.
What is a USB Cable?
USB cables were developed by the computer industry and are primarily used for connecting computers to periferral devices such as printers and keyboards. They are similar to HDMI cables in that they carry digital signals. However, the connectors have a rectangular shape.
Many TVs have USB inputs. They will accept a variety of audio and video file formats, and will allow you to connect devices such as flash drives (thumb drives), external hard drives, and cameras to the TV.
What is a Component Video Cable?
Component video cables have phono (RCA) plugs on the ends. It takes five connections to pass both audio and video. The colors of the plugs on the cable will conveniently match the jacks on the TV or the device. The green, blue and red cables are for the video, and the white and red cables are for the audio.
High definition will work only with the three types of cables mentioned above – HDMI, DVI, or component video cables. The video signals that travel through the HDMI and DVI cables are digital signals. The audio signals are digital in the HDMI cable, and analog for DVI.
What is a Composite Video Cable?
Three phono (RCA) plug connections form the composite video cable – yellow (video), red and white (audio left and right). Composite video is never high definition, although the picture format may display as a wide screen picture.
The video and audio signals for both the component and the composite cables are always analog.
What is a Coaxial Cable?
Coaxial (“coax”) cable is generally black and just a little smaller in diameter than the thickness of your little finger. The connectors generally screw-on and off like a garden hose, unless they are the “quick-disconnect” type that pull off and push on. These cables carry the raw radio-frequency (“RF”) signal, which are the actual TV channels, from an antenna or set-top box to your television. This is the only kind of cable that will connect to an antenna
Observe the center pin located inside the connector. As you can see in the photo, this center conductor must ever so slightly extend beyond the rim of the collar. If it is too short, or bent to the side, it will not make a good connection – it will need to be straightened with a pair of needle-nose pliers. Otherwise, the connector or the whole cable will need to be replaced.
The connector must be crimped onto the cable snuggly. The collar may turn freely, but make sure the body of the connector doesn’t twist or feel loose against the cable. A coaxial cable looses its integrity when its connectors are faulty. See Intermittent TV Signal - Senario 4.
What is a Fiber Optic Cable?
This cable probably ought to be among those at the top of the list. The fiber optic cable uses infrared fiber optics to pass a digital audio signal. Typically, there is a little door that covers the jack to protect it from dust. The door opens as the cable plug is inserted into the jack. The cable plug snaps into the jack. Configurations that use either HDMI cables or optical audio cables will offer the best audio quality that you can have.
Common Sense Rules of Connections
- Cables are hooked up so that one end connects to an output of a device, and the other end connects to its complimentary input on another device. (There may be possible exceptions involving split audio connections using "Y" adapters.)
- The name of the signal, stamped next to each jack, must be the same at both ends of a cable.
The Colors of Plugs and Jacks
To help simplify the process of hooking things up, the consumer electronics industry came up with a system of color-coding the plugs and jacks. Simply connect the cables so that their plug colors match the colors of the jacks on the TV or device.
If you happen to have a cable that physically fits but whose plug color doesn't match the jack color, it is still okay to use it. The signal doesn't care what color the connectors are. Just make sure that the common sense rules mentioned above are followed, as if a cable with the correct color was being used.
The process of troubleshooting may require you to change the way things are connected in order to rule out or isolate certain devices or signal sources. Before you make any changes, it is a good idea to remember how everything is hooked up. You may want to take notes. Some people put labels on each end of the cables near the connectors. You could even take pictures of the cables connected to the devices before you start unplugging things.
To find out how it’s all connected, just follow each cable, one at a time. You may want to draw yourself a diagram. You can ignore the power cords and any wires going to speakers. Just trace your cables starting from the TV.
Some configurations involve a stereo receiver or an A-V receiver. For example, you may have an HDMI cable from a TV input to the A-V receiver output, then other HDMI cables that connect from inputs on the A-V receiver to outputs of other devices. If this is the kind of configuration you have, and you are experiencing issues with signals going to the TV, try bypassing the A-V receiver by connecting devices directly to the TV. If your signal issues go away when you do this, then your A-V receiver is at fault.