Troubleshooting a 1952 Chevrolet Truck Radio?

outoftune · Dec 9, 2024

Hi everyone,

Looking for a bit of help with this 1952 Chevrolet Radio I'm fixing for a friend.

The radio is no longer passing any audio. I have the radio removed and on my test bench for testing.

Can anyone tell me how I can use a bench DC supply to power up this unit to test? And also what I can do as a substitute for the antenna?

The battery in the original truck is 6V car battery.

I have lots of electronics experience with tube gear, but nothing this old. If anyone can suggest a starting point of what to test or measurements to take that would be great.

ccaudle · Dec 9, 2024

outoftune said:
The battery in the original truck is 6V car battery.

Check whether that model uses positive ground or negative ground, I'm not sure the negative ground convention was in place by 1952 or not.

Is that a tube radio, or transistor?

echo zulu · Dec 9, 2024

That’s definitely a tube set

. I agree on verifying the polarity… probably negative ground, though.

A linear bench or “battery eliminator” supply capable of delivering several amps will be needed. A few feet of random wire vertically oriented will do for an antenna.

First thing I’d check for is plate voltage on the rectifier tube. If missing, the vibrator may have croaked. If it IS working, you can usually hear it buzzing.

outoftune · Dec 9, 2024

Yes it's tube! Thank you for the notes on the grounding and I will check the plate voltage and vibrator.

From what I can tell in the lower left the ground and the coil next to it, this is where I connect the bench supply? Do you know approximately how many amps it would need to be?

echo zulu · Dec 9, 2024

It looks like the “A” Fuse connector and adjacent switched dial light connection are where you would connect the +6v. Chassis should be negative. A 4-5 amp supply would probably be enough. Bring the voltage up slowly while watching the current draw. Use an 8-10 amp fuse in series with the hot lead on your supply just to be safe.

JohnRoberts · Dec 9, 2024

Vibrator is obvious suspect....Good luck

===edit
Some of those old vacuum tube car radios didn't suck. I recall as a kid, using one in my bedroom to play music. I powered it from an old car battery. I mostly messed with later 12V radios, but recall one (1954 ford) where I put a 12v battery and starter in the car but kept the radio and dash lights 6V. I even tried tapping 6V from the 12v battery using a thread cutting screw into the lugs on top of the battery (not a long term solution).

JR