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Old 07-14-2013, 10:38 PM
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JimN JimN is offline
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Originally Posted by chevyluv View Post
Well after much digging I think I have found the problem the ground from the stereo does not go to the amp ground or the battery it appears to go around the bow and to the grounding bar. If I cut this wire and run it to the amp or negative terminal of the battery should this solve my problem?
Run it to the amp.

Here's the theory behind this- the power and ground cables for the head unit and anything that would go between the head unit and amp(s) should be as short as possible and should go to the same point where the amp(s) get their power and ground. The easiest way to do this is by using a distribution block for each. One of the head unit's power wires is constantly hot and the other is switched (ignition switch or accessory switch), usually connected to a specific set of wires in the dash. This uses a ground wire that connects to a common point, often a buss strip or one point before heading back to the battery. All of these work well enough as long as there's nothing else in the audio system but if there is more, it brings trouble. An easy way to avoid using a power wire that takes a different path is to use a Bosch-style relay to interrupt the switched wire and use that as the relay's trigger, instead. The relay's input tab (30) connects to the wire that's constantly hot and the output (87a) goes to the head unit's switched wire. Tabs 85 and 86 connect to the red switched wire in the dash and a ground wire, respectively. You can use the old radio ground wire for this.

Electrically, no resistance between the head unit and other electronics is allowable because this causes the power voltage to drop. The voltage will find a path and it doesn't care where it has to go to achieve this. The most common route is through the audio cable shield. The reason this is a problem is because the audio circuit is isolated from the chassis of the equipment and is used for signal that's AC (Alternating Current", not DC. AC and DC on the same circuit is a bad thing and affects the AC circuit's operation, either by introducing noise, affecting gain or by damaging the circuit(s), depending on how much resistance is on a power cable. If the power amp ground cable is lifted, the amp(s)' power supply current will have to pass entirely through the audio circuit and with a high powered amp, or several, it means 50A or more will try to pass on wires that can't support that much. This will let the magic smoke out of the wires.
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