1972 Corvette radio repair source

[Patrick H.]

Working on a 1972 Corvette for an owner that is hoping to get his radio fixed on his way to a possible Duntov. That's hard enough for an unrestored car, harder when your radio doesn't work.

The owner contacted Jerry Rudbeck, and told me that Jerry has such a backlog that he wouldn't even take his name down to put in line for repair.

The car had an 8 track added 34+ years ago, and when that is on the tape will play in the speakers. The radio lights go on and off appropriately and the stereo light even goes on and off when it should. However, zero noise through the speakers when using the radio. Given that we hear a click/pop through the pre-amp in the dash when changing stations we suspect the problem lies there. However, we will find out soon enough when we take it apart.

Anyone know of a good repair source for the radio and/or pre-amp?

Thanks!

[Joe L.]

Re: 1972 Corvette radio repair source

Working on a 1972 Corvette for an owner that is hoping to get his radio fixed on his way to a possible Duntov. That's hard enough for an unrestored car, harder when your radio doesn't work.

The owner contacted Jerry Rudbeck, and told me that Jerry has such a backlog that he wouldn't even take his name down to put in line for repair.

The car had an 8 track added 34+ years ago, and when that is on the tape will play in the speakers. The radio lights go on and off appropriately and the stereo light even goes on and off when it should. However, zero noise through the speakers when using the radio. Given that we hear a click/pop through the pre-amp in the dash when changing stations we suspect the problem lies there. However, we will find out soon enough when we take it apart.

Anyone know of a good repair source for the radio and/or pre-amp?

Thanks!

Patrick-------


Jerry Rudbeck would be my first choice but it sounds like that's not going to be possible in this case.

Something you might try is United Radio in Syracuse, NY. They are an authorized Delco Service Center. However, what I don't know is if they would still service radios this old. But, I would trust them to do a good job if they're willing. I think their web site is www.unitedradio.com

[Dan D.]

Re: 1972 Corvette radio repair source

Maybe I'm out of line here, or I'm missing something. But, since the owner is probably going to spend $300. to $400. anyway, wouldn't he be better off to consider putting that toward locating a correct radio. Even if the dash has been cut; reproductions of that center unit are available.

[Patrick H.]

Re: 1972 Corvette radio repair source

Dan,

I'm not sure where you determined that the dash was cut or that the radio was incorrect.
The 8 track player is mounted in the rear bulkhead between the seats. The dash and radio are 100% correct and original.

Patrick

[Dan D.]

Re: 1972 Corvette radio repair source

Mea Culpa"...I stand corrected. I've obviously made an incorrect assumption. I knew G.M. didn't have a factory ordered option for an 8-track in a Corvette then. We have seen a lot of the after-market units in Corvettes...I just figured it was one of those. I was with Pontiac Motor Division in those days. And, I do remember we had an " under-dash unit" that was available through GM Parts for dealer installation...no reason it couldn't be mounted somewhere else.

[Paul O.]

Re: 1972 Corvette radio repair source

Patrick try and call http://www.wonderbarman.com/ he has good work in the past have not used him in several years.

[Patrick H.]

Re: 1972 Corvette radio repair source

Thanks Joe and Paul.
I'll have the owner contact each of these sources.

Patrick

[Jim T.]

Re: 1972 Corvette radio repair source

Patrick I have used Precision Radio twice for repair on my 1985 Corvette Bose radio. Reasonable rates and quick service and return.DELCO radios are their speciality. 35 years radio repair and 25 years GM warranty work.

Precision Radio
12134 Colwick St.
San Antonio, TX 78216
210-979-0905

precisionradio@sbcglobal.net

web page info using "Precision Radio"

[Patrick H.]

Re: 1972 Corvette radio repair source

Thanks Jim.

I removed the right side dash pad today, and all the wiring looks pristine as does the pre-amp. We could feel the pre-amp buzzing and making noise when trying the radio today, so I removed it from the dash and set it on the floor.

There is an local old time radio repair shop that the owner is going to contact. He talked to them previously and they thought they could troubleshoot it. Now we need to see if they can do that in the car, since it is hardwired to the main radio. If not, we will reassemble and then tackle it after the WI Regional.

Patrick

[Jerry R.]

Re: 1972 Corvette radio repair source

I think the owner may have been referring to Greg T. and not me Patrick. That confusion happens quite often. I have no notes or emails of being contacted regarding a 72 as described.

Greg and I talk regularly and he had stopped taking original radio repair work recently, at least for a while, when he was 26 weeks behind. He's still doing the aftermarket mods on them though with the help of a co-worker.

I'm not maintaining a wait list at all and doubt I ever will again but I won't accept more auto radios than I think I can handle in a two month block. I would have told the owner that so he could check back.

But of more importance, your description sounds like you have a stereo model. That buzzing sound, if it's coming from the firewall passenger side mounted box, is the stereo decoder/second channel amplifier. There's a stereo lamp control relay in it and that snaps on and off wildly on weak signals or noise - especially if the radio has aged components and the alignment is off.

Assuming that's what you are referring to, then I would venture a strong suggestion that both speakers are original and therefore they are both shot (open voice coil). There is another late C3 here now and sure enough, the radio works but the owner apparently did not check the speakers as advised. If you want instructions on how to check them Patrick drop me an email. This is a very common problem with the 70-76's. Greg T. can supply excellent replacements made for that original radio or Ron McGee can re-cone the originals.

Also, Tony Mac can handle that radio just fine as Paul suggested. But, you don't want the local TV repair guy poking around in there! Their best and honest efforts do more damage in an auto radio than they accomplish. Most of my time is spent cleaning up those messes. It's the only time I get grumpy. ;-)

That 72 stereo radio is packed full of well engineered discrete component circuitry and will be repairable for decades to come. And it has untapped capacity and potential. I love the 72's and still have a couple fully restored ones I did for myself back when there was time. It's worth the effort to fix it if the speakers turn out to be bad.

Hope that helped...

_Jerry_

[Ed S.]

Re: 1972 Corvette radio repair source

Patrick,
My advice to you is to follow Jerry's advice to the letter. And if your radio still does not work as desired then be patient and send it to Jerry for a repair / overhaul when he lets you know that he is able to take it and work on it. From very recent personal experience I can tell you that it will be worth the wait. My '64 radio's performance was absolutely awful. After waiting until Jerry contacted me and told me he had a small window of opportunity (reduced workload) I sent my radio to him for a service. I also completed the "shipping" documentation form he requests in excruciating detail - a copy of the form can be found on his website. The more info you can provide Jerry regarding what the radio has experienced, what it does and does not do, modifications to the car's electrical system etc. the better. Why this is important - Jerry will likely get your radio to perform better than new on his workbench but if the environment (installed in your car) that it will be working in has been altered then you may not experience the same great performance.

I got my radio back in about 10 days - appearance wise it is absolutely awesome, and it's performance is off the chart. It works like or better than new. I could not be more pleased with the results. You can also expect Jerry to communicate with you often when he has your radio - expect to get status updates, what he found, what it needs, do's and don't s etc etc. He has an excellent bench side manner if you now what I mean.

We classic Corvette enthusiasts enjoy the benefit of a very small handful of subject matter technical experts that help keep our beloved Corvettes operating and looking like or better than new. Jerry is one among those experts.

[Gary R.]

Re: 1972 Corvette radio repair source

Does anyone know where to get the on/off volume pot? I had my 72 radio upgraded years ago and found the pot was left in and is now shot. I have to turn it on very slowly to "catch" it to get the radio to work. Otherwise if I just turn it on it won't work. If I go to turn the volume up or down in a normal manner it will cut out completely. I was told to shoot some WD40 in the stem and work it back and forth but I fix differentials not electronics so what do I know!

Thanks

[Ed S.]

Re: 1972 Corvette radio repair source

Garry,
I think you need to talk with Jerry. Don't know if NOS or service replacement pots are available. My guess is no - that said, I would suspect that you or someone in the radio repair business could cannibalize or salvage a serviceable one from an otherwise un-serviceable radio, and then apply some maintenance to the part to make it completely serviceable.

I am not a radio repair expert but I have read and heard many times - DO NOT spray WD40 into radio components especially control pots. There is a product that will clean pots, DEOXIT, haven't used it myself but all the radio guru's highly recommend it.

[Joe L.]

Re: 1972 Corvette radio repair source

I think the owner may have been referring to Greg T. and not me Patrick. That confusion happens quite often. I have no notes or emails of being contacted regarding a 72 as described.

Greg and I talk regularly and he had stopped taking original radio repair work recently, at least for a while, when he was 26 weeks behind. He's still doing the aftermarket mods on them though with the help of a co-worker.

I'm not maintaining a wait list at all and doubt I ever will again but I won't accept more auto radios than I think I can handle in a two month block. I would have told the owner that so he could check back.

But of more importance, your description sounds like you have a stereo model. That buzzing sound, if it's coming from the firewall passenger side mounted box, is the stereo decoder/second channel amplifier. There's a stereo lamp control relay in it and that snaps on and off wildly on weak signals or noise - especially if the radio has aged components and the alignment is off.

Assuming that's what you are referring to, then I would venture a strong suggestion that both speakers are original and therefore they are both shot (open voice coil). There is another late C3 here now and sure enough, the radio works but the owner apparently did not check the speakers as advised. If you want instructions on how to check them Patrick drop me an email. This is a very common problem with the 70-76's. Greg T. can supply excellent replacements made for that original radio or Ron McGee can re-cone the originals.

Also, Tony Mac can handle that radio just fine as Paul suggested. But, you don't want the local TV repair guy poking around in there! Their best and honest efforts do more damage in an auto radio than they accomplish. Most of my time is spent cleaning up those messes. It's the only time I get grumpy. ;-)

That 72 stereo radio is packed full of well engineered discrete component circuitry and will be repairable for decades to come. And it has untapped capacity and potential. I love the 72's and still have a couple fully restored ones I did for myself back when there was time. It's worth the effort to fix it if the speakers turn out to be bad.

Hope that helped...

_Jerry_

Jerry------


Are the 1972 Corvette radios significantly different than the 1968-71?

[Jerry R.]

Re: 1972 Corvette radio repair source

Hi Joe!

Nope, the difference is mostly cosmetic. There are minor circuit component value variations from beginning (68) to end (72) but when you master one, the rest are fun.

All of the amplifiers in the stereo models in that date range can deliver noticeably greater amplitude and a more robust frequency response with very minor component additions. And the aged components, including the intermediate frequency transformers, are repairable if not replaceable.

And the poor 70 through 72's that are restricted by 4X6" speakers can drive a second set of speakers if the bias voltage is re-adjusted. The variable control to accomplish that is already accessible for the radio amp itself and also for the second channel amp in the stereo de-mux (decoder) box on the firewall.

Even the 68-70 models can add a 6"X9" speaker to each channel and redistribute the available amplifier power more effectively in the lower end of the audio spectrum.

The mono's followed the same component pattern variability as the stereo's but changes were minor by my definition and they just didn't have the performance potential of the stereos (and they should by engineering/circuitry comparisons). Still, it's easy to add a 3 to 6 acoustic decibel bump up to them.

73 and after are good performers but when the power switch fails or the DM (Delco Module which was a discrete component configuration in a plastic container - forerunner to an integrated circuit) preamplifier fails, life gets expensive. I'm sure a lot of unused spare parts went to the dump when GM consolidated dealerships. Special original unused parts (with house numbers) are incredibly rare. And 76's used a DM that unique compared to it's predecessors.

Hope that helped. Guess Ill try to answer Gary's question above next. That's the most common problem now that will send original radios to the dump (or eBay to be dumped on someone else). GRIN