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Old 07-10-2003, 08:13 AM
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Voltage Drop

Hey Guy's! For the most part I have totally replace all the major wiring harnesses, external voltage regulator, horn relay and fuse panel in my 65 Chevy SWB Pickup. Everything is working fine and done correctly (from what I can tell). Here's the deal, when I run the stereo/CD player by itself, it's fine. But when I turn on my lights it gets all distorted (like the power is being drained). If I turn a blinker on it gets distorted and fades in and out (hence the off/on pull of electricity when light is flashing) The stereo/CD is a cheaper model with a direct hot wire thru the ignition and a link thru the fuse box, those are the only sources of power. Defiantly not a fancy setup. The wiring harness jobs were done by my self and done pretty much to factory, except I have an HEI dist that took some modifications on the engine harness. After reading several threads on HotRodders I'm lead to believe maybe it's an alternator/ext. regulator issue and that maybe I should upgrade to an alternator w/internal voltage reg. Would that really help? I'm not running other electrical devices when this happens?? I could see if I was running the a/c, heater, radio, lights and dome light might cause a power shortage?? But just the radio and a flasher? The altenator is a rebuilt and was in the truck when I bought it, so it could be defunked? The best way to test the alt. is to test the battery and make sure it's 12 and when running it should be 13/14 right? What do you guys think about all this business??

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Old 07-10-2003, 09:29 AM
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Be sure you have a good ground. I made a ground plate out of a flattened copper pipe fitting and drilled a series of holes in it and mounted it under my dash. I ran a #10 wire through the firewall and connected it to my engine where my battery ground connects. Now when I add anything to my dash I just bolt the ground to that plate.

Also, check out this guy: http://www.madelectrical.com/

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Old 07-11-2003, 03:00 AM
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Well not having all the specs for the stereo i.e. wattage etc here goes. It sounds like the main lead to the fuse block is close to maxed out when drawing to much current. The gauge of wire will determine what you can draw and how far. If you want it swiched with the key then I would install a relay from the piont your drawing from now to ground on the coil side. Then run a 10-12 gauge wire right off the battery terminal to one side of the switch contacts on the relay. Next take the other contact to your CD changer. That should give you enough power. If you want a good source for relay circuits check outBosch relay info
There are some good diagrams for what you need

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Old 07-11-2003, 03:38 AM
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Reroute your power wire as far as possible from the distributor, power surges from a nearby plug wire are famous for doing this...even through the firewall.

RF noise can cause a whining sound in the stereo and also do funny things with your power wiring.
“She may not look like much, but she's got it where it counts, kid. I've made a lot of special modifications myself.”

— Han Solo
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Old 07-22-2003, 12:35 PM
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I'm thinking along the same lines as Mark -- the radio needs to be wired differently ... double-check it's ground ... maybe assign it it's own fuse. And maybe a new alternator with an internal regulator is a good idea, too, Patrick.

54 Chevy Pickup
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Old 07-23-2003, 11:02 PM
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an easy solution is to run a 12v fuseblock off your ignition switch. Run thicker wire and solder in a noise limiter into your power wire to the radio. Some of the lower end radios you can get don't have built in limiters next to the transformer. It will pick up all kinds of noises.
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