The radio works but only gets 1 station AM and comes in good.What needs to be done to get better reception. More stations Clean ground lift the antenna from base up or down.Tried to remove the radio knob and adj small screw but no help
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Re: C3 Radio
Triming the radio chassis to match the antenna is one aspect of fine tuning... You're tweaking a variable capacitor match the specific impedance of a particular antenna + lead-in cable. Results really only show up under severe AM 'fringe' reception conditions and don't make much difference in a major metro setting.
One problem that's common is good FM reception and poor AM reception (radio only locks in on the strongest AM stations). Generally, this results from a fractured/broken antenna lead-in cable and often happens after a car's interior has been restored and the original lead-in cable was moved/handled in the process of replacing the carpet.
It's an easy situation to trouble shoot though. You simply un-plug the existing antenna from the rear of the radio chassis (banana plug) and connect temporarily, a known good antenna with an assistant walking the cable out of the cockpit toward the rear of the car.
If all of a sudden, you start to pull in AM stations you couldn't get before, you know the problem lies with the continuity of your cabling from the radio to the rear antenna mast! You can grab an off-the-shelf, el-cheapo, replacement radio antenna with captive lead-in wire at Wal-Mart for less than $10.... -
Re: C3 Radio
Denny, Jack is right. I have hung a cheap antenna out the window to check if the original antenna is working. Is your fm allright? In a am-fm radio, the first 3 stages of the radio share the same circuit so poor reception on am usually means poor reception on fm. Is your radio a am-fm mono or a am-fm stereo? And what year? If hanging the cheap antenna doesn't help the reception then there is a problem in the radio. To get to the antenna connector on the radio, remove the radio side panel in the passenger compartment. the antenna plugs into the side of the radio. I have done this before because taking out the radio is a chore. I know because I was a Delco radio warrenty man for over 20 years. Let me know if I can help.Comment
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Re: C3 Radio
Richard ,Thanks for getting back.
1972 am fm mono, passenger side pannel, good call.Like you said could be a chore.How many grounds do I look for? Is the only one by the gas tank. You Know I took my kids I pod put it in the lighter and raido works great.The other thing I take the antenna off at night so the cover fits snug.Anything there at the base I did wrong.Comment
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Re: C3 Radio
here is another one for you richard---72 am fm stereo replaced the 2 speakers with correct ac delco 10 ohm speakers all worked fine for about a month then the right channel or speaker quit making sound---did the usual trouble shooting by swapping leads on the speakers to verify good speakers and wiring---the right channel/speaker cone activates or pops when the radio is turned on but will not make sound---is it possible that the tuner knob is in a bind ? note that i do get the stereo indicator light and that i'm on a known stereo station---when i put the radio back in it seems as if there is more tension on the tuner than before---thanks for any and all help,philComment
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Re: C3 Radio
Denny, Taking off the antenna at night should be no problem. The only ground strap is at the plate under the antenna. that plate is the only ground plane for the antenna. A good ground there helps. Is your FM working allright? This will help in determining what is wrong. let me know. RichardComment
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Re: C3 Radio
Phil, On your radio, there are 3 pieces to it. The main radio, the stereo miltiplex unit and a heatsink for the left channel output transisitor, which is mounted above the heater box on the inside of the car. The right cannel sound goes thru the stereo mulitplex. On the bottom of the radio close to the main power plug is a round 9-pin plug that goes from the radio to the mulitplex unit. This plug provides main power and audio to the right channel,. I do not think that is were the problem is because you said that the stereo indicater light works on the radio. If the audio was not getting to the multiplex, the indicator would not work because the light is controlled by the mulitplex. BUT, check it anyway, I have seen a lot of weird problems. Most likely the problem is that the DS-501 output trnsisitor on the heatsink that is on the muiltplex has gone on vacation. This usually happens when speakers go bad and the improper load is put on the transisitor.By the way, this radio was used in 70, 71 and 72. They made very little changes. In the Delco manual, all 71 and 72 listings refer to the basic 70 manual for repair.
To troubleshoot the tuner binding problem, loosen the nut that is just behind the tuning knob. If the binding goes away, then the collar the the nut is on has either twisted or is getting cocked to one side. All that collar does is to provide a way to fasten the radio to the cluster. The tuning rod passes thru it to to tuner of the radio. You might also spray,(very carefully and very little) some light silicone oil right were the shaft goes thru the collar. Sometimes dirt gets in there and binds it up.
The pop in the speaker can be there even if the transisitor is bad. Open base to emitter junction. Let me know if any of this helps. RichardComment
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Re: C3 Radio
Richard,
Just wondering if you have any ideas? I've got a 75' AM/FM STEREO and the FM is not working,( just a hissing noise ) and the AM is low on the volume side now. Any ideas?
Ken.Comment
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Re: C3 Radio
Richard,I cleaned the group of wires above the gas tank and the raido got worse AM had to turn up volume all the way and 2 stations and were soft sound.Fm regular volume 1 station, statit on all.I borrowed a doner antenna and will hook up at lunch time Chicago The FM you realy have to fine tune the knob back and forth to get the station.Comment
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Re: C3 Radio
Denny, Sorry I did not get to you sooner. It sounds like you have a problem in the radio itself. I have seen this before with the symptons that you describe. With very little Am and touchy Fm, the problem can be in several places, Internal power supply, or one of the signal amplifier stages. You are probably going to have to pull the radio.But it should not be a difficult repair. If you have a repair guy, fine, If not let me know. I still have all my repair stuff. let me know. RichComment
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Re: C3 Radio
Ken, I don't think it is in the antenna, but put a substitute antenna in just to verify. The antenna lead plugs in to the passenger side of the radio. Hang a cheap antenna out the window and see uif it is better. With no FM at all, that will usually be the IF (intermediate Frequency) IC in the radio that has gone away. If I remember right, delco went to IC's about 74 or 75, I have not had a chance to look this up. Try the antenna, and let me know. RichComment
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Re: C3 Radio
Richard Time is tuff to find.I have a show in June so the radio will not come out till after.But I will say at 7:00 today, I went back to your post and got your name on paper your are the man for radio info. Only to find your new post.Richard thank you for your time and at the end of June if I may, talk again.DennyComment
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