radio poltergiests

Billschroeder5842 · Mar 1, 2014

I was listening to the FM in my factory radio while driving around in my 75 roadrunner today and heard a very soft *pop* and then nothing. I switch over to the AM band and the radio works perfect. Switch back to FM and nothing.

Is there any way to fix this or is the radio shot? IT seems funny to me that the FM band could be out while the AM works just fine.

Any ideas?

69Bee · Mar 1, 2014

Without being too technical, AM and FM are completely different. Perhaps a capacitor or transistor in the FM circuit blew (soft pop).

ZombiePopper · Mar 2, 2014

Was it playing oldies?
Is it a 57 plymouth fury?

Sorry couldn't help it,
just thinking about Christine.....

GASGZLR · Mar 3, 2014

Check to be sure the antenna is plugged in correctly and is making a good ground through the fender mount. AM will work without an antenna, but FM has to have one.

idrivemopar · Mar 11, 2014

My 73 had a similar problem, turned out to be a $1.18 zener diode that blew out, thankfully I know some armature radio guys that were able to diagnose and fix it for me.

A383Wing · Mar 11, 2014

GASGZLR said:
Check to be sure the antenna is plugged in correctly and is making a good ground through the fender mount. AM will work without an antenna, but FM has to have one.

actually, it's the other way around...at least with all my FM radios

74Monaco CHP · Apr 6, 2014

I replaced the one in my 75. I found it was apparently replaced at some point with a factory re-conditioned one in 75. I guess the original owners sparkomatic 8-track and sound mixer might have caused that. He just cut into the harness,. I put a newer Mopar one in with cd - cassette and am/fm and repaired the wiring. I did find the speakers were with the exception of one all dry rotted away. They were also replaced.

Bruzilla · May 15, 2014

A383Wing said:
actually, it's the other way around...at least with all my FM radios

Actually both AM and FM require an antenna, but most AM radios use an internally-mounted antenna that is just wire wrapped around a solid core and you can't see it unless you open the radio. The wavelengths of FM signals require the longer antennas we find on our cars, and if that antenna isn't connected all you're going to hear from most FM radios is a very low hiss.

Billschroeder5842 · May 17, 2014

I just ending up replacing the unit. the great thing about 75's are that they are super easy to work on! total swap time about 20 minutes.

radio poltergiests

Billschroeder5842

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69Bee

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ZombiePopper

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GASGZLR

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idrivemopar

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A383Wing

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74Monaco CHP

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Bruzilla

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Billschroeder5842

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