Bench Testing MoPar 6V Radios

[Bingster]

I think over the winter I'll take out the radio in my '47 Desoto and clean it up on the bench. Can I just use a 6V car battery and hook it up directly to the radio or is there some intermediate part that makes the battery voltage useable in the radio?

[Frank Elder]

Couldn't you use an ignition switch, not sure how you would ground the radio.

[BobT-47P15]

I think you would just ground the radio to the other post of the battery....

everything in the car is positive ground.

[Norm's Coupe]

The radio only works when hooked up as a positive ground to the battery. Hook up the positive battery post to the radio case and the negative to the hot lead of the radio. You can use the post at the rear of the radio that attaches to bracket that holds the radio in the dash as the ground.

[Frank Elder]

Still would be nice to have a toggle or ignition switch to interupt pwr while working on said radio, instead of messing with the battery posts for disconnect.

[DonaldSmith]

You might want a circuit breaker or fuse in line, just to keep things from melting down. I clamped the wires to the battery posts with hose clamps.

Don't forget to connect the aerial and speaker.

I went through the whole process. I woke up the vibrator with intermittent jolts of 120 volt AC current, using an old cord and switch from a power drill. I replaced the capacitors. I blew out some big capacitors by connecting them with the wrong polarity. The radio forum guys that had been helping me gave me the dummy award. Although the case is positive ground for the 6 volt circuits, it's negative ground for the high voltage side. Bummer. Blew out five bucks worth of capacitors.

It still would not work. I reported the voltages at the pins of the tubes to the radio forum, and the word came back that there was a short somewhere. I found a short between the the volume wire and its coax sheath. I fixed that, and two guys on the radio started yelling. Success! Jump for joy!

[Frank Elder]

May we have the radio forum address?

[DonaldSmith]

I pulled my radio file. The site that had so much useful information is www.nostalgiaair.org.

They have an Antique Radio Technical Forum, and they also had four pages of schematics for my Mopar 602, which was made by Colonial Radio. Look inside the case of your radio for some labels to identify the manufacturer and model.

(My wife was looking over my shoulder when I wrote this. She thinks it is so cool that we can help each other with this forum. I got a lot of help along the way, so I should chip in when I can be of help.)

[Frank Elder]

Thank you Donald!