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Alternating current in charging system |
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cnagorka
AMC Apprentice Joined: Jan/02/2014 Location: Saint Albans, W Status: Offline Points: 200 |
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Posted: Oct/31/2014 at 1:23pm |
Hello all:
I'm stumped. I installed an aftermarket car stereo in the '60 and it lasted about three months, then it started acting so strangely I had to get rid of it, and bought a second one. This one works fine with the key in accessory position, but when the engine is running the audio is either non existent or cuts in and out so much it's not useable. Long story short, I checked the voltage coming in on the Ignition wire, and there's actually more alternating current than direct current! (about 18V AC and 12.5V DC) That can't be right- it has the original generator and electromechanical voltage regulator. The TSM doesn't say anything about rectifying the current coming from the generator, which makes sense as it isn't supposed to be putting out any AC at all. I have a feeling any aftermarket anything I put in here is going to go bad- I don't have much experience with this kind of system; does anyone think I should be looking at the generator itself? The TSM does mention "polarizing" the generator, but if the windings are going the same way there shouldn't be anything "alternating". I tried putting diodes in line with the power leads to add rectification but it didn't help. I added a noise suppression condenser on the coil and that didn't do anything either. (I assume the Ignition wire feeds the coil and shouldn't be getting anything backwards from it.) Any input appreciated. CN Edited by cnagorka - Oct/31/2014 at 1:26pm |
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cnagorka
AMC Apprentice Joined: Jan/02/2014 Location: Saint Albans, W Status: Offline Points: 200 |
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Well...I found that if I reverse the leads I don't get any of what I thought was AC...which is even more confusing. (This is on an analog voltmeter). Maybe what I'm seeing is the cycling of the cutout...either way something is making the radio very unhappy.
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FuzzFace2
AMC Addicted Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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Ok first what are we working on year/model/motor wise?
Dose it run a generator or alternator? Why are you checking “the voltage coming in on the Ignition wire” and where is this wire located at? What wires did you reverse to change the readings? Change them back the way they were. Or was this your meter leads? I am no expert but my take on how I would do this. Find a fuse in the fuse panel that gets volts with the key in run & ACC position. Check this fuse with meter-red to the fuse and black to anybody ground and why do you get? Should read 12 volts +/- a volt. This is where I would pick up power at for the radio. Ground should go to and good clean body ground. Speaker wires both + and – (2 to each speaker) should run from radio to the speakers. Do not run the speaker – to body ground. Dave ---- |
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TSM = Technical Service Manual
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cnagorka
AMC Apprentice Joined: Jan/02/2014 Location: Saint Albans, W Status: Offline Points: 200 |
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It's the 1960 Classic 195.6 in my avatar. It has the original Delco-Remy generator and mechanical voltage regulator. The "ignition" wire is coming from under the dashboard, it's the one that supplies voltage to the coil, and is used for turning the radio on when the key is turned to accessory or run (as opposed to the "battery" wire, which is hot all the time and keeps the memory settings intact). The leads I reversed were the meter leads.
Both leads for each speaker are coming from the radio itself, the body ground isn't used for the speakers at all. The radio itself has a good ground on the metal dashboard. In my day job working on pipe organs, I've seen incredibly strange things happen when radio frequency noise (that is, from sparks) gets into sensitive equipment not meant to be interfaced with older stuff. Old radios didn't have digital tuners and software, and that may be the problem here. |
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FuzzFace2
AMC Addicted Joined: Jul/05/2007 Location: Angier, N.C. Status: Offline Points: 10356 |
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I would not use that wire that feeds the coil. Does your car not have a fuse panel? I have seen posted that older car did not have a fuse panel.
Now for testing only what if you ran wires from radio to the batt. does it work as it should or still have issues? If works then I would wire the radio up using a relay and triggered from your IGN. switch but not from the wire feeding the coil. Dave ---- |
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TSM = Technical Service Manual
75 Gremlin X v8 for sale 70 Javelin 360/auto drag car 70 Javelin 360/T5 Street car |
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cnagorka
AMC Apprentice Joined: Jan/02/2014 Location: Saint Albans, W Status: Offline Points: 200 |
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Nope, no fuse panel. Just out of curiosity I connected both radio leads to the "battery" line so it was on all the time, and when I started the car, sure enough it started cutting out even though the "ignition" wire wasn't even in the circuit.
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vinny
Supporter of TheAMCForum Joined: Jan/05/2012 Location: Calgary Status: Offline Points: 2837 |
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They used to use something called a growler to check the generator armatures that there were no open spots to the commutator. Commutators regularly got dressed on a lathe. Other than that if the brushes, bushings and field windings are good the generator should be OK. I don't know if anyone still tests them for output or whatever. Old cars certainly had generators and radios working together without problems. Some of them nay have been tube radios.
You could take the easy way out and put on a newer style Delco CS130 alternator. They have various mounting configurations and you may find one with somewhat similar mounting ears. I'd check the junkyards. Your generator pulley could probably be swapped to the alternator.
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carnuck
AMC Addicted Joined: Mar/31/2010 Location: Seattle Status: Offline Points: 3942 |
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Sounds like the body to battery negative ground is missing, so it's backfeeding through the radio via the antenna.
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