1970 AM Radio Voltage?

[69/70Plymies]

I'm having trouble getting an AM radio working in my 1970 Sp. Satellite. I checked voltage at the fuse box. The main red wire terminal showed 10.9 volts, but the red w/ white tracer terminal (for the radio) only showed .01 volts. Surely,that's not enough to operate the radio, right? I have already cleaned all the connections at the firewall bulkhead. Any info. or advice is greatly appreciated.

 

[mopar 3 B]

Power wire voltage for the radio should be same as battery voltage. The radio ground strap if in car is connected?

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Power wire voltage for the radio should be same as battery voltage. The radio ground strap if in car is connected?

 

[HT413]

Check the volts across the battery terminals. If it's 10.7 you have a low battery. The 0.1V happened because you measured + to +, the little difference was due to resistance in the wire.

If you have 12v at the battery and 10.9 at the fuse box, you have some oxidized connections. Best way to clean is dip in a salt and vinegar solution for maybe 30 sec or a minute. Then rinse thoroughly and spray with a non-conductive lube for corrosion protection. Do that to every connection between the battery and the radio.

A great way to test things is check resistance from + terminal on the battery all the way across to the fuse box. Should be really close to 0 ohm. Then clean each connection as stated above and check again. With each cleaned connection, should be less and less resistance.

 

[69/70Plymies]

TO MOPAR 3 B: For testing, I had the radio laying on the floor, but I did have a copper cable from the ground post on back of radio to the dash frame. So, I think it was grounded. Thanks.

TO HT413: The battery has been sitting for awhile. I did check it's voltage before starting and it was at 12.4 v., but at the fuse box it was 10.9 v. The .01 was from my + meter probe placed on the radio terminal of the fuse box and the - meter probe to dash ground. After I brush cleaned the terminals at the bulkhead, I sprayed each with electrical contact spray, let dry and then packed each with dielectric grease. Was this procedure OK?
I will check out the ohm resistance tomorrow. Thank you very much!

 

[65-440]

one wire is key on batt voltage, the other one should be for the screen lighting

 

[69/70Plymies]

Well, the battle goes on. One thing I discovered was that the voltage coming into the fuse box (red w/ white tracer) at bottom of fuse was 12.3v, but at the top of fuse was only 11.4v. I cleaned the fuse holder and installed a different 20A fuse. This got me 12.3v top and bottom. Unfortunately, with key on, the radio hot wire still was all messed up. It would read from 2.5 to 11.2v from turning the key on different times. Even at 11.2, the radio would not work. I ran a jumper hot wire from battery to radio and shazam, the radio worked great. That speaker (from a '69 RR) has not made sound since 1975. But I still have my radio wire voltage problem. I wonder if the ignition key switch socket is the problem? The switch was new 2-3 yrs. ago. What do you fellows think, now? It's hard to think real well when you're working on this for hours in 29 degree temp. Thanks for any additional ideas!

 

[mopar 3 B]

Check the ignition switch to harness connector at the steering column.

 

[HT413]

Here's a wiring diagram for your car. Sounds like you have some work to do with oxidized connections. Keep in mind that if you have this issue with the radio circuit, you likely have this issue with the other circuits as well. The charging circuit and headlight circuit draw enough current to easily burn your car to the ground (especially the oem ammeter circuit), so I'd recommend going through the whole car. Remember, a salt and vinegar solution will remove oxidation from copper almost instantly. It's far more effective than those store bought sprays, ya just have to rinse really well.

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http://www.mymopar.com/index.php?pid=27

 

[69/70Plymies]

To HT413: Unfortunately for me, I think your right. I'll start with the fuse box, then the harness connection at the steering column. What's your opinion of how I cleaned the bulkhead (using dielectric grease)? Should I re-do it? Lastly, I guess I'll have to dig into the ignition switch on the steering column. I put a new aftermarket ign. switch in 2-3 yrs. ago. The old one just pulled right out and I just slipped the new one in. Later, I read the proper procedure in the service manual and it was a lot more involved than what I did. Could this be a problem, too? Thanks for the schematics.

 

[HT413]

To HT413: Unfortunately for me, I think your right. I'll start with the fuse box, then the harness connection at the steering column. What's your opinion of how I cleaned the bulkhead (using dielectric grease)? Should I re-do it? Lastly, I guess I'll have to dig into the ignition switch on the steering column. I put a new aftermarket ign. switch in 2-3 yrs. ago. The old one just pulled right out and I just slipped the new one in. Later, I read the proper procedure in the service manual and it was a lot more involved than what I did. Could this be a problem, too? Thanks for the schematics.

Most dielectric greases don't really deoxidize the connections. There is some good stuff out there that does, it's called Deoxit I think. Good stuff, but the connection needs to be cycled on and off a bunch so it scrapes the copper oxide off the connection. Vinegar and salt solution dissolves the copper oxide almost instantly, but now that you have the grease on, you need to degrease the connection first.

 

[bigmanjbmopar]

Just out of curiosity did you have you antenna plugged in when you are testing?

 

[mopar 3 B]

Most dielectric greases don't really deoxidize the connections. There is some good stuff out there that does, it's called Deoxit I think. Good stuff, but the connection needs to be cycled on and off a bunch so it scrapes the copper oxide off the connection. Vinegar and salt solution dissolves the copper oxide almost instantly, but now that you have the grease on, you need to degrease the connection first.

What are the mixture rates of salt and vinegar? What do you use to flush the solution?

 

[HT413]

What are the mixture rates of salt and vinegar? What do you use to flush the solution?

1 cup of vinegar and a tablespoon of salt. That's it. For rinsing, I would find a nice non-conductive spray to displace water. Youre not trying I neutralize the vinegar, just rinse it out and displace any water. Depending on the location, maybe try some wood alcohol in a spray bottle, maybe some carb cleaner, or even electrical contact cleaner... stuff like that. Then slather it in dielectric grease and it'll stay clean for a generation. Here's a link to a thread where I showed a step by step process when I tracked down an overcharging issue. Like yours, it was really a high resistance issue. I even show some experimental results for the vinegar/salt solution.

http://www.forbbodiesonly.com/moparforum/showthread.php?56124-How-I-fixed-my-overcharging-issues

Trust me, I'm a chemistry teacher.

 

[69/70Plymies]

Well, I opened up the steering column and got re-educated on the internal design. I need to correct my previous statement. I replaced the lock cylinder 2-3 yrs. ago, not the ign. switch. I removed the actual ign. switch and found out it was very worn out. I took another out of a parts car and installed it. As soon as I get the dash components back together, I'll find out if that corrects the voltage to the radio. Also, checked the dash "ground" bolt under the dash on the pass. side and it needed serious cleaning.

I'm happy to report that the radio works great, now. Either the new ignition switch or cleaning the dash "ground" fixed the voltage problem to the radio. Thanks to all for the help.