radio poltergiests

[billschroeder5842]

I have a radio situation on my 75 roadrunner.

While driving today and listening to the FM, there was a soft "pop" and then the radio has no sound. I switched over to AM band and the radio works perfect.

Is there anything I can do to get the FM back or is the radio shot? Seems goofy that one band will work and the other won't.

Any ideas?

[A383Wing]

sounds like you lost a transistor or capacitor....it can be fixed..but how much is the question

I got 2 AM-FM's here that fade out after they are run for a bit...I know it's a capacitor...but I'm no radio repair guy

[Dino]

I have the same thing happening, after about 15 minutes the radio cuts out.  Am radio.  If I let it cool for a few it'll turn back on.  I know it's a capacitor somewhere.  I'd get it fixed if I actually used that radio. 
Bill if you have a real electronics repair shop near you, those guys can find the culprit in no time.  Problem is actually finding someone who still knows this stuff.

[fy469rtse]

Your right Dino, I used to know one,
And now he's joined the rest looking at the grass from the wrong side

[Pete in NH]

Bill,

It sounds like the FM section has a problem. There are two separate receivers, one AM, one FM that share a common audio amplifier in your radio. That is why one section can work and the other doesn't.

383wing is likely right that either a transistor or capacitor is gone. 40 year old electrolytic capacitors are a problem. A good approach is to just replace all of them in the radio. Usually there are only a half a dozen or so. Otherwise you replace one and six months later another goes bad. These radios can be repaired as they are fairly simple with no custom integrated circuits.

[Dino]

Minor thread hijack here...how hard would it be to turn a stock AM radio into a modern one with all the bells and whistles?  Like the ones you can buy for an arm, a leg and half your butt.  It should not be that hard to take one apart and install FM, aux and usb inputs, sd card maybe?  I have never tried anything like that but it would be a fun winter project!  I think I have a free winter coming up in 2018.   

[Pete in NH]

Hi Dino,

I think its mostly a mechanical repackaging job, if you can get the modern radio disassembled to its major subassemblies. But, I think it will be very time and labor intensive which is why the guys that do it charge so much not to mention adding a very healthy profit. You likely wont know exactly what you're getting into until you try it.

[Dino]

Pete, no doubt this would be an involved job.  I was looking at my AM radio and it looks really nice still, never was removed from the dash either, still hooked up to the center dash speaker.

I think I will look for another on ebay to play with.  Getting the thumbwheels to work will be a challenge I'm sure.  It may not be worth to do it but it sure would be nice.

I'm also looking at installing a smart phone holder in the ash tray and let that be my mp3 player, FM radio and GPS.  That would be nice as well.

[Dodge Don]

Not sure this is the issue here but caution that you cannot use an old factory radio with modrn speakers....the ohms are different and you can fry your factory radio. I learned this the hard way