Mystery Radio Part

[Joseph K.]

On page 435 of the 69 Assembly manual there is what appears to be a heat sink that is mounted remotely from the radio. The Assembly manual calls it a convector ASM.. 1 Does anyone know what it is, 2 What it Does.. and 3 if it is broken will the radio play. Thanks for the help

[Michael G.]

Re: Mystery Radio Part

Joe,

The heat sync or convector is mounted (at least on my '72 and '74) behind the passenger side dash pad. Do not know what this part does however the radio will not perform without it or is dysfunctional.

[Terry M.]

Re: Mystery Radio Part

On page 435 of the 69 Assembly manual there is what appears to be a heat sink that is mounted remotely from the radio. The Assembly manual calls it a convector ASM.. 1 Does anyone know what it is, 2 What it Does.. and 3 if it is broken will the radio play. Thanks for the help

The convector, or heat sync, contains the output transistors that power the speakers. If it (they) are broken the radio will not play, and I think there is some risk to other components inside the main part of the radio. Jack Humphrey has posted in the past with the numbers of the transistors in the convector, but I am not sure what good that does those of us not schooled in radio repair.

[Joe L.]

Re: Mystery Radio Part

All-----


Most auto radios have the output transistors included as part of the radio assembly. However, for "packaging" reasons on 68-76 Corvettes, the output transistor and heat sink were separated from the main radio chassis.

So, we should think of the "convector" as an integral part of the radio and just as important as all the rest of the stuff that's "in there". It's not like an accessory sort of thing.

[Jim B.]

Re: Mystery Radio Part

All-----


Most auto radios have the output transistors included as part of the radio assembly. However, for "packaging" reasons on 68-76 Corvettes, the output transistor and heat sink were separated from the main radio chassis.

So, we should think of the "convector" as an integral part of the radio and just as important as all the rest of the stuff that's "in there". It's not like an accessory sort of thing.

From an Electronics point of view (my EE degree is showing) this part is the driver for the speakers. Joe is right, it is integral to the ability of the radio to output power to the speakers. In cars before 68 this was accompished through the use of matching transformers in the radio amplifier. With the advent of solid state (old term) radios, the transformers were eliminated and the direct drive transistor was used. They put out a lot of heat therefore they need a heat sink with air cooling and since the heat was pretty high they were separated from the radio itself. Later cars, as the technology improved, have this heat sink attached to the back of the radio console.
Technically this was cheaper and produced a far superior sound.

[Glenn D.]

Re: Mystery Radio Part

Great reply by Joe and Jim. Perfect explanation of the part.

[Jack H.]

Re: Mystery Radio Part

Much that has been said is correct about the function of the 'convector' from a big picture view. It's a part of the radio. It performs the final audio drive function. But, here's a little more detail...

In electrical engineering terms, we model current components a tad differently than we do voltage components. The upstream components of the radio operate on voltage waveforms (demodulate, filter, shape, amplify, Etc.) but when it comes to finally driving the speaker (essentially an electro-magnet), we want to pump CURRENT into the speaker's voice coil.

Prior to the invention of the transistor, that task was done via reasonably large/heavy transformer(s) and vacuum tubes. The transistor simplified this since it gave us a device that could amplify a voltage waveform and generate DIRECTLY a matching current waveform as the output.

So, starting in '58 GM began using transistors of their own manufacture (Delco Remy) based on their technology license from Bell Labs. In the case here, we're talking about a DS-503 transistor constructed from rather archane germanium technology.

I won't go into depth about the pro/con issues of fabricating transistors from silicon vs. germanium vs. iridium, Etc. But, Texas Instruments patented the use of silicon while other Bell Lab licensees continued to flog a dead horse with their germanium technology...

Bottom line, the convector is no more than a DS-503, germanium transistor, mounted on its own heat sink with interconnect wiring. Some versions of Delco radios mount it integral to the radio chassis while others for space/cooling considerations, mount it externally.

It's job is to transform the final audio waveform of the radio from a voltage wave into a current wave to make the speaker play without the need for vacuum tubes and transformers.

[Joseph K.]

Re: Mystery Radio Part

Thanks for all the help. I am going to take the radio out and have it repaired. I am also going to take the convector out and send it with the radio. Wish me luck. I looked where the raidio is and it is jamed in there. GM probably did not have room to mount it on the radio so they mounted it remotely. Thanks