64' Ford Falcon Radio Buzzing

[stj]

Re: 64' Ford Falcon Radio Buzzing

not touch the knob, touch the contacts at the rear of it.

[R_J]

Re: 64' Ford Falcon Radio Buzzing

The control should have 3 terminals in a row on it, by touching the center one with your finger, or while holding the shaft of a small screwdriver you will inject a signal, (or use your audio generator to inject a signal, you do have one?) if not this will work.
or try touching where I marked, it should give you some indication if the amp section is working

[caphair]

Re: 64' Ford Falcon Radio Buzzing

The control should have 3 terminals in a row on it, by touching the center one with your finger, or while holding the shaft of a small screwdriver you will inject a signal, (or use your audio generator to inject a signal, you do have one?) if not this will work.
or try touching where I marked, it should give you some indication if the amp section is working

Thanks I'll try that. The area you marked is that the amp side? Curious how you can tell.

Also not too familiar with audio stuff so been doing some reading, do all radios have an IF section? Or only older stuff

[stj]

Re: 64' Ford Falcon Radio Buzzing

on a pot, the center pin is the wiper and the outer pins are the track.
usually the wiper goes to the amp, the far right of the track goes to the audio source, and the far left goes to ground to eliminate hum at low volumes.

so for this test, make sure the volume is set middle or high, or the center tab will probably be grounded.

[R_J]

Re: 64' Ford Falcon Radio Buzzing

this is the audio path after the i.f. section (from what I can tell) The audio is rectified by the diode and fed to the top of the volume control, the center of the volume control (which controls the level) goes through the coupling cap. and is fed to the driver transistor base, that transistor drives the output transistor.
so by injecting a signal at the volume control you should get a loud buzz indicating the audio circuit is working.

[caphair]

Re: 64' Ford Falcon Radio Buzzing

Ok so touching the volume knob a hum is heard. Not super loud but audible. It's the left of the volume knob that produces it and touching at the - of the capacitor RJ circled produces same him but little louder. Does this mean the amp circuit is fine and I need to look somewhere else?

I also provided additional pics. I don't see where an antenna would be plugged into this thing. Unless it uses the car chassis as one?

[R_J]

Re: 64' Ford Falcon Radio Buzzing

I marked the antenna input, What do you have connected there? I hope you did'nt blow up the input. I also marked the antenna trimmer
This is what an antenna plug looks like coming from the antenna, the cable is a coax, outside shield with center conductor

[caphair]

Re: 64' Ford Falcon Radio Buzzing

I marked the antenna input, What do you have connected there? I hope you did'nt blow up the input. I also marked the antenna trimmer
This is what an antenna plug looks like coming from the antenna, the cable is a coax, outside shield with center conductor

That is just a wire that was there when the unit was given to me. I didn't hook anything up to it.

Does that trimmer need to be adjusted at all? I haven't touched it just curious

[R_J]

Re: 64' Ford Falcon Radio Buzzing

You don't need to adjust the trimmer, only adjust it when its installed with the cars antenna, Its used to match the antenna so you can get the best reception

[caphair]

Re: 64' Ford Falcon Radio Buzzing

You don't need to adjust the trimmer, only adjust it when its installed with the cars antenna, Its used to match the antenna so you can get the best reception

Ok so what do you think now? Problem outside the amplifier section?

[caphair]

Re: 64' Ford Falcon Radio Buzzing

So I spliced a longer wire to that existing wire used for the antenna and now I hear the original complaint.

All it does is buzz at various frequencies. Sometimes a louder more prominent buzz other times more faint depending on the station.

Wish I knew what was the antenna input originally would have eliminated some troubleshooting steps BUT it was appreciated as I'm learning from them.

So now I'm guessing the issue isn't from the amplifier section.

I only see 2 electrolytic caps that I'll try to replace. Any others I might be missing that's visible to others? Do the values need to be exact or could I use higher ones?

Also I'm curious why that output transformer had such a low reading from E to C if it's considered good still?

[R_J]

Re: 64' Ford Falcon Radio Buzzing

Just a thought but are there florescent lights where you are working, if so turn them off, the could be interfering with reception. I doubt changing the electrolytics will change much. It could be the local oscilator is not working, without a scope I don't see how you can do a proper diagnosis
there are three tuning slugs in the tuning section, make sure all three are moving when you adjust the tuning control, I have seen where one was stuck or broken and not moving.

[caphair]

Re: 64' Ford Falcon Radio Buzzing

Just a thought but are there florescent lights where you are working, if so turn them off, the could be interfering with reception. I doubt changing the electrolytics will change much. It could be the local oscilator is not working, without a scope I don't see how you can do a proper diagnosis

No fluorescent lights. However I noticed if I touch the "antenna" aka the speaker wire that's hooked up into that input then a couple stations come in clear.

Are those electrolytics just part of the amplifier circuits?

[R_J]

Re: 64' Ford Falcon Radio Buzzing

If its tuning in stations, then its working, these radios were not that sensitive, not like radios made later, you may need a longer antenna wire,
That black 5uf is for audio coupling (looks like it was replaced once) the grey 20uf could be ok, I think its for the avc circuit, you can just bridge another one accross them and see if it makes a difference
I have'nt worked on one of these type radios in many years.

[stj]

Re: 64' Ford Falcon Radio Buzzing

a groundplane would help - a baking tray under the radio should be a big enough surface area.

[caphair]

Re: 64' Ford Falcon Radio Buzzing

If its tuning in stations, then its working, these radios were not that sensitive, not like radios made later, you may need a longer antenna wire,
That black 5uf is for audio coupling (looks like it was replaced once) the grey 20uf could be ok, I think its for the avc circuit, you can just bridge another one accross them and see if it makes a difference
I have'nt worked on one of these type radios in many years.

I'm getting one station in clear. No other station just buzzing.

Does it matter what value electrolytic I use for replacements? Or they have to be exact value?

[R_J]

Re: 64' Ford Falcon Radio Buzzing

for the 5uf use a 4.7uf for the 20 use a 22uf, these are standard values
How many radio stations are around you, how far are you from their transmitter? maybe take it outside and try it
this radio uses one transistor as the r.f. amp, not like a high gain fet's of todays radios.

[keeney123]

Re: 64' Ford Falcon Radio Buzzing

for the 5uf use a 4.7uf for the 20 use a 22uf, these are standard values
How many radio stations are around you, how far are you from their transmitter? maybe take it outside and try it
this radio uses one transistor as the r.f. amp, not like a high gain fet's of todays radios.

So you should have a capacitor on the input to the antenna. It is usually a round looking thing about the size of a dime. It looks like it could be an old flat looking potentiometer. This needs to be turned with a fiberglass screwdriver to tune in the antenna to the radio.

[stj]

Re: 64' Ford Falcon Radio Buzzing

that sounds more like a variable capacitor.

[R_J]

Re: 64' Ford Falcon Radio Buzzing

I already pointed out the antenna trimer in post #22. It won't match worth a dam using a piece of wire, but adjust it if you like.