Radio crackles while turning volume knob- 1970 U79 stereo

[Mark E.]

Otherwise, AM and FM work fairly well (tone quality from the two dash speakers isn't much to brag about, but I suspect normal).

The radio hasn't been used in many years. Should I try exercising the volume control to see if that helps?

Or apply a radio tuner cleaner?

Or is this a problem that's more involved and will just get worse?

[Stephen L.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

The problem appears to be some dirt in the volume potentiometer. I was able to correct the same problem on my C2 radio by carefully

[Mike E.]

[Alan D.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

Add some light oil to the pot (volume control)

[Leif A.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

Mike,
Fairly common issue with these old cars. They sit too long without being "exercised"...especially, things like the radio. Mine had the same issues. I used the product listed below (DeoxIT D5...availabel from Radio Shack). Removed the control knob, shot some on the shaft and worked the shaft back and forth. The more you use the radio the less the problem will appear. If you don't use it often, this fix seems to last about 6 months before having to do again. But, a 15 minute job at the most. Good listening!!

https://www.amazon.com/Caig-Labs-Cleaning-Solution-Limited/dp/B07CGFNGHW

[Gary R.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

Hi Mark
I have the same deal with my 72. I used Deoxit to spray down the pot shaft and it did help but I want to pull the radio when I get time and go through it.

Here is a link to last year

https://www.forums.ncrs.org/showthre...n-I-turn-it-on

[Ed S.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

Mark - DO NOT spray anything on to your volume control mechanism to clean it other than a product called DEOXIT.

I had my original 64 radio repaired a few years ago by Jerry Rudbeck - probably the best C2 radio repair guy ever (he is retired now) In addition to giving me a detailed breakdown of what he did to it, he also send me a short note with recommendations to keep it operating in great shape.

He told me that one issue that is common to mid 1960s GM radios is the design of the on/off & volume control. It contains a stack of small carbon disks that have a tendency to corrode - and get dirty - that is what causes the static when you turn the knob. If you use WD40 or similar products it permanently damages the disks. Jerry recommended using a spray product called DEOXIT - designed for cleaning electric contacts. It is an aerosol and is cost about $15 for a small can. Radio Shack carried it - you may have to order it on line. Great stuff - a few short shots into your volume control and it fixes the problem. Trust me - this is the only thing that works without doing damage to the volume control.

[Mark E.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

Hi Mark
I have the same deal with my 72. I used Deoxit to spray down the pot shaft and it did help but I want to pull the radio when I get time and go through it.

Here is a link to last year

https://www.forums.ncrs.org/showthre...n-I-turn-it-on

I saw this thread during my initial research, but thought it was only about a pop noise when turning on the radio. If I read further I would have learned about treating the crackling while adjusting the volume.

It reads like an ad for DEOXIT. Sounds like good stuff.

[Frank D.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

DeOxit is all I use now for connector cleaning and radio knobs. Its really good for spraying in those pesky bulkhead connectors near the master cylinder and cleaning up corrosion there...and in tail light/parking light sockets and anywhere else you can think off....like the rear harness connector behind the DS kick panel... Buy 2-3 cans....it can go fast once you figure out all of its uses...

[Ed S.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

I saw this thread during my initial research, but thought it was only about a pop noise when turning on the radio. If I read further I would have learned about treating the crackling while adjusting the volume.

It reads like an ad for DEOXIT. Sounds like good stuff.

For the record - I don't have a vested or financial interest in DEOXIT other than the fact that I use it and it works better than advertised. I really is great stuff - hard to find these days.

[William F.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

Why not other brands of electrical contact cleaners? CRC mskes one.

[Ed S.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

Why not other brands of electrical contact cleaners? CRC mskes one.

William, I don't know the answer to that question. What I do know is that Jerry Rudbeck, who retired from C2 radio repairs & restorations a few years ago and was (still is) regarded as perhaps the best radio technician around -- for early GM radios, highly recommended Deoxit.... and only Deoxit. Other stuff may work but for me, it is not worth the risk. I suppose if you compared ingredients on the labels - if they list the ingredients and they were the same there would be no difference. But again - why risk it.

[Joe R.]

Re: Radio crackles while turning volume knob- 1970 U79 stereo

William,

A friend of mine is an electronics technician and has been for probably 40 years or so. He swears by Deoxit also. There may be other products that work as well but I doubt it. It isn't all that expensive, so why take a chance?

Joe