Instructor Daniel Tramposh Talks Car AudioJune 20th, 2012 by Coyne
I wanted to address some of the common electronics issues that are brought up in courses here at Coyne College. An interesting question about car audio systems was asked the other day. Although not taught as a specific subject at Coyne, car audio systems often come up as a discussion topic. Car audio can be used to help explain theories relevant to the EST program such as basic electronic theory, home theater, DC voltage, etc.
The specific car audio question that came up was about fuses on the main power wire in a car stereo system. A student told me he had work done to his car stereo by a professional installation shop. The student purchased a 4 awg power wire kit. The fuse and fuse holder that came with the kit were installed in his car trunk.
This is not the first time I have heard something like this. I was a Mobile Electronics Certified Professional (MECP) installer for many years and logged somewhere in the neighborhood of 3,500 cars. The fuse and fuse holder that comes with amp install kits are made to go on the main and power cable. That is the cable that runs from the battery all the way to the amps. It IS NOT intended to protect the amps. THE MAIN POWER FUSE IS INTENDED TO PROTECT YOUR CAR! It protects your car from fire, complete electrical system failure, a damaged computer, etc. Basically it protects your vehicle from catastrophic electrical failure.
Why? Let’s quickly review car electronics. In a vehicle, the positive side of the battery and electrical system is connected via wires. These wires are insulated. The negative side however is simply connected to the metal chassis of the car. This is often called ground. The term “ground” comes from AC voltage terminology as in home wiring where the “ground” is actually used as part of the circuit. Therefore in a car, the entire metal chassis and body is attached to the negative side of the battery.
Imagine that you ran a 4 awg power wire to the trunk of your car directly from the positive power terminal of the battery. You also have fold down rear seats and the power wire runs right by the hinges. One day you put that seat down and the hinge pinches the wire and cuts through the insulation making contact with the wire inside. Remember the seat hinge is attached to the car chassis which is the electrical negative. You have now created a short or a closed circuit between the negative and positive terminals of the battery. THIS IS VERY BAD NEWS. If you have a fuse on the power cable this is when it will quickly heat up and “blow” (opening the closed circuit and saving your car from destruction). If your fuse is mounted in the trunk, after the short, the wire will heat up continuously and it will likely cause a fire. The fire may start to burn out some of the electrical components in the car. Trust me I have seen this. You will no longer be able to drive the car, either because it is now a pile of ash or the electrical system is damaged, computer and all. All circuits are protected in the vehicle by a fuse somewhere and your amp power wire should be no different!
AAS Degree Programs, car audio, Coyne College, Daniel Tramposh, Diploma Programs, Electronic Systems Technician, EST, low voltage
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