The Stovebolt Site Forums The Shop Area The Electrical Bay The Radio Bench 41 radio project

I hesitate to write that I am asking about a radio from a 41 chevy sedan. The car is driven by a fine stovebolt engine, and who knows if I might install the radio in my truck? In any case I have a radio repair looming, and I few questions, and I value the good advice doled out here.
My great-aunt drove the car until 1974. During the 50's she had trouble with the neighbor boys sneaking into the garage at night to listen to the radio, draining the battery. She had the Chevy dealer disable the radio. I can't see what they did - the fuse is there and all the tubes, there is no obvious damage or dangling wires. When I start the radio it still draws on the battery. No sound, and there hasn't been any as long as I have known the car, which is my whole life.
The model number is 985695. I want to have a working radio and in my teenage years I was obsessed with old radios. I hope I can dredge up some old skills or luck.
But I live in Sweden now, and there is no longer any AM radio here. My idea is to attach an input jack at the volume control so that I can run an mp3 player or smart phone and keep it in the glovebox. I know this can be done, but I don't know if it is as simple as I hope.
But I still want to know that the radio works. Any idea how I can test the receiver without local AM signals?
My plan is to replace the capacitors and the vibrator, maybe even have a try at the ss OZ4 Denny has engineered.
Here are a coupla pictures.

Radio 1
Radio 2

Thanks for the help

Karl

Go ahead and ask all the questions you want about that radio. It is a good Chevy radio. I have a couple under my bench. If you want the circuit for it, I am sure I can get that for you.

Usually the vibrator stops working. If you want to revive it, it usually needs to be taken apart and cleaned. I am not always successful at that but I keep a couple of mechanical ones around for testing. When I am finished with a radio I intall a new electronic vibrator.

You should replace the electrolytic capacitors that will be in the can and all the wax covered paper ones. The mica capacitors usually don't cause much of a problem.

How about that idea of running an input through the radio? I've seen posts about a RediRad thingy that does all the things I am hoping for but costs a bit. Makes me think that using the radio as an amplifier for external devices won't be as easy as I hoped.

Plus, can I test the radio function without an AM station in this part of the world?

I found a radio bulletin on the web 6D-833 which include the schematic for this radio. Do I need anything more?

The circuit for providing the input that you want was posted here some years ago. I will try and find it.

Do you not have any AM stations? I don't know what to suggest if you don't. I use a signal generator on my radio bench.

Ok so I found a reference of how an MP3 input is added to an older radio. There are two problems to solve. First is the connection into the audio section and second is how to combine the two channel stereo inputs of an MP3 into a mono input because the radio only has mono capability. Here is a link to the HAMB where it is explained. I will look through my material to see if I can find the actual hookup for the truck radio. MP3 Input / The HAMB

I think I have this figured out. When you get to the stage where you want to add the MP3 input, I can offer some help if you need it.

Any of you MacGyver types have any idea how I might make a signal generator from - say - a washing machine and a broken bicycle?

Here comes another question for Truckernix! I took it all apart today, one of my pushbuttons is broke so I suppose I'll have to buy a set of 6. The ones sold by Chevs of the 40s are made of ivory colored plastic, my old ones are sort of a clear yellow plastic. How are the ones on the radios you have stashed away? Are there other suppliers of slightly different models? I expect I'll have to be happy to find these buttons at all.
All the tubes are "Genuine GM Parts" and the vibrator (after I tore it open)seems to be functional. I understand I will be wise to replace it with a solid state piece in any case.

Oh, and when replacing the wax capacitors, what should I use for a modern replacement? There seem to be a dozen varieties - none of them are wax.

My radios have tan coloured buttons. I don't there are multiple suppliers for the buttons but I could be wrong.

To replace the wax covered tubular capacitors, I use a modern tubular capacitor as illustrated on this page. Capacitors For some reason I can't see them listed but either of the yellow types I use. the orange dips listed are just as good. You will want a voltage rating of at least 400 V Dc. For the electrolytic in the can, I use the separate ones that are tubular. I disconnect the leads from the can, install a solder terminal block to hold the wire connections and then attach the separate capacitors. The negative side must go to ground. I will send you a PM on how to test the vibrator. I use a mechanical vibrator to test with after I have completed the capacitor work. That is because the new solid state vibrators will not survive a short.

I am working on the old vibrator just now. I have a newer solid state model, but hope to use the old one while getting the radio running.
The old vibrator don't vibrate. The can is open, it looks like a pretty simple device - an electromagnet running a those vibrating contacts. I have tried tweaking it here and there. If the magnet draws as it should, it should be a matter of cleaning the contacts and adjusting the gaps around the contact, right? Does anyone possess first hand knowledge of reviving these vibrators?
I might point out that I am a long ways away from the old surplus parts that drift around the American market...

Karl

Oh. and Truckernix, can you insert station labels in your tan buttons? If not, what do you do?

Maybe the radios I have are 1942 models but they don't have labels. For the 1940 radios, new labels can be made up to make them look right.