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Discussion Starter #1 (Edited)
Just got what appears to be an original AM radio for a Camaro/Firebird. Now I just need to test it but there isn't a wiring plug. It has 3 leads recessed in the back, assuming 1 for 12V and the other 2 for the speaker, with a chassis ground. Anyone know which lead is which before I take it all apart or worse fry it because I guess wrong?

What ohm speaker did it use, or more important what range is acceptable to use for testing?

All the buttons move freely and the push buttons work perfectly as well. It would be sweet if the radio actually works also, but not the end of the world if it doesn't.

Not sure where the real part number is, but the numbers above the dial display are 7298249 and it fits perfectly in the dash of my 67.

-shoe
 

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First, do you have the plug installed in the 9/12 pin connector? The radio won't work w/o it. I think one can even damage it w/o it. Check here for plug stuff:

http://www.camaros.net/forums/showthread.php?t=44715

Do you have an AIM? The pictures kind of hint at what's going on... The speaker plugs into the left (ground/neg.) and middle (pos.) terminals. The one on the right is the 12V power terminal. This is viewing the plug from the back. You are correct that the radio chassis is where the ground is applied. Here is a link for that:

http://www.camaros.net/forums/showthread.php?t=178208

I'm pretty sure the deal w/ the speaker is one above 8 ohms. So, 10 ohms is good. 4 ohms is bad! I used a 8.5 ohm out of a '86 pick-up and it worked fine.

Check this out to see about your radio's application. You need to know the part number, though...

http://www.chevelles.com/radiotech/index.html

Ton of info:
http://camaros.org/forum/index.php?topic=5342.0

The faceplate number is different than the model/part number. Mine has a label with that info on it. So, if yours fell off, you might have to luck out that someone else mentioned the faceplate number. Do a search... My 986824 model radio has 7298474 on the faceplate.
 

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Discussion Starter #4
Looks like the same radio. This is an AM only, with the antenna hole and 3 contacts for the plug connection (missing). I asked this on one of those threads you listed (thank you) but am not clear yet if the negative speaker lead has to be grounded to the chassis also.

I hooked it up to an 8 ohm speaker and only grounded the chassis. I got lots of static and then a little smoke so I killed the power immediately. Hope I didn't just ruin it.

-shoe
 

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Looks like the same radio. This is an AM only, with the antenna hole and 3 contacts for the plug connection (missing). I asked this on one of those threads you listed (thank you) but am not clear yet if the negative speaker lead has to be grounded to the chassis also.

I hooked it up to an 8 ohm speaker and only grounded the chassis. I got lots of static and then a little smoke so I killed the power immediately. Hope I didn't just ruin it.

-shoe
Just hope you cut the power right away...8 ohms are a no no for car radios...too much resistance. You may have fried a few transistors in the radio? Always go with 3-4 ohm when dealing with the 12V in vehicles.

capt
 

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Hmmm, one thread says the radio has 10 ohm written on it. I used an 8.6 ohm and it worked great. Course, this WAS with a power supply. I could have had the current set very low...

http://www.camaros.net/forums/showthread.php?t=178208

shoe,
You have the adapter plug installed, correct? Here is a picture:



Here is what my plug socket looks like and how I wired it to my power supply and speaker:



I had also just plugged my new repro antenna in and stood it up...

My radio is PN 986824:


Here is the number on the faceplate, 7298474, which is different from the PN:


Maybe you should get more feedback about what type of speaker to run. I'm pretty sure the original one STILL in my dash is 10 ohm. I just went out and checked. It is 10 ohm...
 

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Cb, you have an FM radio, hence the jumper and different faceplate and part number, stenciling showing the AM & FM radio bands.
AM radios don't have the jumper and a different faceplate showing only AM radio band.

You must hook the speaker ground to the radio to complete the control for the amplifier, otherwise, smoke is let loose as you've seen, probably killed a biasing resistor for the speaker driver, aka, amp section.

Always wondered how much smoke they packed into the radio when made and long it would last.....
 

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Right. I have an AM/FM. My bad. For some reason, I was thinking one could get an AM multiplex. Well, really not completing my thoughts. That wouldn't make sense...

Funny! We used to say, "He let the smoke out of it" at Intel! :p
 

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Discussion Starter #9
I guess I got really lucky. I grounded the speaker to the chassis and stuck an old coat hanger in the antenna slot and fired it up again. Not only didn't it smoke, it actually worked and sounded pretty good on my 8 ohm speaker. The volume control knob is loose internally though and when you move it the static returns but it might be a simple fix. Feeling pretty good about my $100 purchase.

-shoe
 

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Really lucky two times? I would have thought that one should only connect the speaker negative to the radio's speaker negative? That would complete the internal circuit? I imagine that yes, the amplifier section mentioned by Everett would eventually have the same chassis ground as the rest of the circuits. But...

Anyway, I'm glad the radio functions. Personally, I wouldn't try it again or install and wire it until you were VERY clear on how it should be wired. Third time may not be a charm!

P.S. for Everette. I forgot to mention that I knew that my faceplate was different. Come on, AM vs. AM/FM. But I figured I would show shoe my label(s) w/ the part number(s) and that the number on the faceplate is different...

I guess I should cut down on my "thinking out loud" habit... :p
 

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Yes, CB, you were showing the faceplate where the part number was located, not a bad idea.

Loose volume control might be the lock nut to hold it in place.
Static from the volume knob might be eliminated by spinning the bejesus out of the knob to wipe off the burned spots, maybe along with a spray of RF Tuner cleaner.
 

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The radio part number and the number on the faceplate are different. But I imagine that the faceplate was used on the same part number radios... So, it MIGHT narrow it down to a few possibilities?

Good one! I am missing a few of the nuts and a couple washer, too. According to the AIM... Figures.
 

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The radio part number and the number on the faceplate are different. But I imagine that the faceplate was used on the same part number radios... So, it MIGHT narrow it down to a few possibilities?

Good one! I am missing a few of the nuts and a couple washer, too. According to the AIM... Figures.
Info in the mail re. mutli-plex speaker hook ups.

capt
 
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