Radio

[Lawrence S.]

I have bought an original radio for my car and the guy said it works. I have hooked it up. I guess correctly. I have power to the radio (light is on) but I can't get any white noise or sound etc. I have the radio out of the car on a bench with and antenna hooked up, positive from the radio to speaker and negative from speaker to radio. I am hooking up the speaker from the three spade clips on the side of the radio. My question is why are there three spade clip hook ups off the radio? If I move one of the spade clips off the radio the dial light goes out. I feel like there is some crazy ground required that I can't simulate on the bench. I don't want to put the radio in the car and it not work. I have a radio in the car now (aftermarket that works). Any help on the correct way to hook up would be greatly appreciated.

Save the wave.

Lawrence Shaw

[G B.]

I'd like to help, Lawrence, but...

what year model Corvette are you talking about?

The speaker harness is a wiring pigtail different from the radio power terminal plug on '63 - '67 Corvettes. But, I guess you might be working on a post-'67 with a separate amplifier.

The three male spade terminals on the side plug are power for sound, power for dial light, and ground.

[Don G.]

Re: Radio

Many public libraries have Chevrolet service manuals. check to see if yours has one for your year. They usually show a pictorial of each Chevrolet model radio (Camaro, Corvette, etc). Also, several shark models have a separate "heat sink finned casting" mounted on the fire wall high on the passenger side inside the car. It has some electrical components mounted on it. If your model is supposed to have it, it won't work without it.

In any event, I would take it to a local car radio service center that has been in business for years. They usually have a technician that knows old radios.Check the yellow pages.

[Bob R.]

Re: Radio

If your car is a mid year you must use an original style speaker. It has an amp built into it. If you plug the radio into a standard speaker it will not work and could damage the radio. I just replaced my radio I pluged the connector into the back of the radio, attached the black wire to the case for ground and connected to the speaker harness and antenna. It work as original.

[Jack H.]

Close....

but technically incorrect. The Corvette speaker from late straight-axle days through mid-year era has an impedance matching transformer on it. This overcomes certain dynamic range limitations of the DS-501 speaker drive transistor. This is one of the oldest forms of post Bell Labs invention known to man being made from Germanium vs. Silicon....

Other GM radio systems also used speaker mounted transformers (E.g. Cadillac from the late 50's/early 60's), but most Chevy passenger cars had enough under dash space to mount the matching transformer inside the radio chassis and leave the speaker 'bare'.

BTW, once the matching transformer was incorporated into the design of the radio, it's presense provided a natural filter 'pole'. Designers, knowing it would be there, 'colored' the frequency response of the radio's spectral output to take advantage of it.

Without the matching transformer in place, off-the-shelf speakers, regardless of their modern quality/efficiency characteristics, sound TERRIBLE! Plus, it's just a matter of time before you 'toast' the DS-501 drive transistor in a Corvette radio without the matching transformer being present.

We saw this time and time again at our shop. Prior owner decided to replace the radio speaker (water damage, or just 'improve' sound) and installed a high quality contemporary replacement speaker. Typically, the telltale was in-line connectors in the radio-harness were cut & discarded.

Almost immediately the radio burned out its output drive transistor with the customer/owner complaining of inferior sound quality. 'Expert' technicians who did the speaker swap scratched their heads--couldn't be the fault of the speaker; worked fine with other Chevy cars of the same period.

RIGHT! Those cars had the matching transformer built into the radio chassis.
Hey, doesn't anybody out there acquire the GM/Chevy service literature and read it???

Oh, well, the natural fall out of all this is a good selection of correct, original Corvette radios offered on eBay each day with some kind of disclaimer as to their current functionality....