Needs E-Caps or volume control switch?

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Hi guys, I'm checking a mid-60's am radio and when I bench test it I can tell there's power going to the radio. The only "static" I hear is when I first turn the volume control up. Then nothing. Would that be a problem with the volume control or is there an eletrolytic cap problem? I doubt the radio has ever been recapped. Thanks for your help!
 
Are all of these old radios the same or similar?

If so, you may want to try to find a schematic for them. You would likely get more suggestions/help if we could see the circuit.

If you can't find a schematic, post the numbers off of the radio and the manufacturer and maybe someone else can help you find a diagram.

If all else fails and you want to repair these in the future, you may need to trace the circuit and draw out the schematic. It's time consuming but a schematic makes servicing a piece of equipment much easier.
 
Perry Babin said:
Are all of these old radios the same or similar?

If so, you may want to try to find a schematic for them. You would likely get more suggestions/help if we could see the circuit.

If you can't find a schematic, post the numbers off of the radio and the manufacturer and maybe someone else can help you find a diagram.

If all else fails and you want to repair these in the future, you may need to trace the circuit and draw out the schematic. It's time consuming but a schematic makes servicing a piece of equipment much easier.

Hi Perry,

I have the schematic for the radio but reading it is like Greek to me. I've sat down and studied it and made some sense of it but not enough to do me any good.

This might be a dumb question but (I ask this honestly) how can you tell what's wrong by reading a schematic? Shouldn't physical symptoms be able to tell me what the problem is?
 
The schematic tells you where the current flows. It's like a roadmap. After you learn the symbols and understand how the devices work, you can find the problem. Many times, there is absolutely no visible clue to tell you which device is defective.

If you have an electronic version (or can scan your paper version), send me a copy of it or post it on a server and provide a link to it. If you don't have access to a server and want others to be able to help you, I can drop it onto one of the servers I use.

If no one here can help, maybe you can get someone like anatech to help. Some of the older discrete circuits can be tough to troubleshoot (particularly some of the radio reciever circuits).
 
I'll get the schematic scanned tomorrow or Sunday and post it if the file size isn't too large. I don't have a server though so you might have to walk me through that if you wouldn't mind. Thanks so much for your help Perry. This is fun to learn but can also be very frustrating too.

Btw, the links in your signature are excellent. I'm going to print and read them. Hey, I might learn something! :)

I just received my Canon SD 750 yesterday. The best camera I've ever had (but I'm not a camera expert, I just know what looks good). :)

Thanks again!
 
I tried Photobucket and it resizes the images. This probably won't work well for a schematic diagram. If someone knows of a similar server that doesn't resize the photos (1024x768 seems like the max at photobucket), please post the name of the server.

If no one has a better suggestion, email it to me at babin_perry@yahoo.com.

Have it scanned at 300dpi. 16bit grayscale will probably be the best for the original unless it's in color.

You probably wouldn't want to try to print the entire site. Someone printed the car audio site and it was more than 500 pages.
 
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