1976 radio problem

[Edward I.]

I need some ideas on my AM/FM U69 option radio. It just stopped playing a few months ago and I checked the AGC 20 amp fuse. It looked fine, no break in the "wire".
Are looks deceiving ,or just try a new fuse ??? Could it be something else ?? Any ideas would be appreciated.
Ed

[Joe R.]

Re: 1976 radio problem

Ed,

I would check the fuse with an Ohmmeter to be sure it's good. If it's bad, you could replace it, but odds are it will blow again. Does the radio light up at night? Is the connection to the speaker OK? Is the speaker good? Try the easy things first, if all else fails you may be looking at pulling the radio. But you knew that already!

Joe

[Edward I.]

Re: 1976 radio problem

Thanks Joe , I sometimes think that things should last forever when you don't use them . 38 years and 17,000 miles , you can't say I abused the radio .
I'll trouble shoot in that logical order .
Thanks again
Ed

[Edward J.]

Re: 1976 radio problem

Ed, To add to Joe's post, When you turn on radio do you hear anything through the speaker? sometimes things like the radio antenna and its ground can be a problem. Generally you'll hear something when the radio in switched on (Static or click).

[Edward I.]

Re: 1976 radio problem

Ed J. - I looked for a light, listen for a sound, any sound (click or pop), nothing ,zilch, nada, zero . I think I'll pursue the "NO POWER GETTING TO THE RADIO" FIRST . Like I mentioned to Joe , the fuse looks
good but without an Ohmmeter near at hand (I have one up in New York) , I could swap another 20 amp fuse from the fuse block , and "see" if that's the problem. I should have tried that when my body was wedged in the foot well with the interior light in my face. I hope the new Vettes are easier to work on when it comes to changing a fuse. I'll give it one more attempt before I check the antenna, etc. .

Ed

[Edward J.]

Re: 1976 radio problem

Ed, sorry to say instead of about 6/8 fuses try about 30 to 40 I Really never counted them on 02 corvette but there is a sh_ _ load of them. Ed on some occasions I have seen a connection issue between the terminal ends of the fuse. corrosion can be possible.

[Edward I.]

Re: 1976 radio problem

Thanks Ed, I just tried swapping another 20 amp that was good - (directional signal ) to the radio and nothing. But I like your thought about possible corrosion at the terminal ends. You would think with the changing of fuses(3X's),that might clean the thermals ?
I'm shot for today - if I loss 25 lbs , and get hands like a ten year old, that would help. Tomorrow is another day here in sunny Florida . I have some fine emery paper that I can try cleaning the end terminals and give it another try.
Dinner time -- Ed

[Jerry R.]

Re: 1976 radio problem

Two more thoughts for what it's worth Ed. When you have the ohm meter handy, attach the black lead to the radio case and the red to either of the outside power connector terminals on the radio (the center terminal is case ground also).

Flip the power switch on and you should read continuity. Move the red lead to the other outside terminal and do the same thing - look for continuity. If you see continuity on both, you now know the two sections of the power switch (radio power and dial lamp power) are working. If they aren't, the second thought is they have failed which is all too common. In 73 and later, some of the switch controls Delco received started using cast and some used plastic internal parts. They easily wear out. And those later switches are not worth the trouble to take apart and try to repair. I made a replacement part for one but only because it was a museum car (and I'm a sucker for a mission impossible task). It took hours so look for a donor radio.

It's also worth checking continuity of each 4X6" speaker after they are disconnected from each other and the radio (so that a good one doesn't mask an open one). The voice coil wires snap under the black liquid tape type material on the front of the cone. With age that black material sets up hard and won't flex anymore and the extremely thin wire severs. Since the speakers for a mono radio are wired in parallel, one can be open and you might not notice it until the second fails.

Since you have no ohm meter with you, you can always put a 1.5 volt battery across the speaker leads and listen for the thump sound. No sound - no good... Past that, it's pretty unlikely that the fusible resistor has croaked in the radio. Those things never seem to fail before something else does.

Good hunting! _Jerry_