Bought extra battery; bench testing radio

[DonaldSmith]

Sam's Club had a group 1 battery for $21 something, $32 something with core charge and tax. It's been on the shelf a while, but it should still be good. The battery in the car is really old, so it can't hurt to get a new one.

I really wanted an extra battery so that I could bench test my Mopar 602 radio from my 47 DeSoto Custom Suburban. I got a little knowledge off the internet on how to troubleshoot my radio. plus an Imperial site technical booklet, so now I am dangerous.

I had trouble getting consistent multi-meter readings, so I went to Radio Shack and got some new slip-on alliigator clip ends for the test leads. They really make a difference.

I put a 10 amp circuit breaker in series between the positive post and the radio chassis. Then I see that the booklet says 14 amp fuse. If I trip the breaker a lot, I 'll get a 15 amp breaker. I use a jumper with alligator clip to a hose clamp on the negative post. I disconnect it when not testing something.

6 volt power: I have power to the pilot light and to some pints on the chassis, but should also have 6 volts to the tubes to warm up the filaments. Maybe the tubes are so old and silvered inside that I can't see them glow. I can put the multi-meter to the sockets to see if I have 6 volts to them.

Vibrator: It does not buzz, even though there is power to it. I took the can off, and the points look good. The springy points thing moves one way but not the other. I'm trying to understand the circuit. I'll play with it a bit. I'll apply some intermittent persistence. It's worked on other things.

Meantime, if anyone have any tips, chime in.

[BobT-47P15]

Probably some capacitors in that radio. They tend to wear out over time I think. Son in law fixed his guitar amp with some capacitors he bought at an electronics store. I think they just have to be the same "value" as the old one.....maybe can look just a bit different.

[Don Coatney]

Donald;

Remember your radio is polarity sensitive. Make sure you have it connected positive ground.

[DonaldSmith]

Donald;

Remember your radio is polarity sensitive. Make sure you have it connected positive ground.

Yep. Positive post connected to chassis.

[Plymouthy Adams]

I have a friend that has been doing older tube type radios for a time now..he also recommend reflowing solder connections..this corrects cold solder joints..a not to uncommon problem in older chassis's.

[DonaldSmith]

Looked for legible diagram for my Mopar 602. Some antique site wanted to sell me diagrams at a buck a page, but they tipped their hand. Teh Mopar 602 is a Colonial 671A. I googled that manufacturer and number and found nostalgiaair dot org, and downloaded a 3-page pdf.

Diagrams call for a R43697 vibrator, and shows 4 pins connected, ground, power, and two alternating grounds to ends of transformer primary coil. (Power to middle of coil. Only half of coil energized at a time, but direction of current alternates as vibrator ... vibrates.)

I have a 43697M. Took the works out of the can. Points look good. But only three pins wired. Looks original. Power makes it move in one direction but not back. Can't figure it out. Wrong vibrator?

Need a break. What hair I have left on my head is beginning to smolder.

[Norm's Coupe]

Is your radio a 602 or 802? Both were used back then. My 48 Plymouth has an 802 in it. That could be why the vibrators are not the same. The radio should be marked either 602 or 802. If not, just count the tubes. 602 radios only had 6 tubes. 802 had 8 tubes.

[DonaldSmith]

But I also have a diagram for an 804, and the vibrator connections are the same.

No nibbles yet on my posting on the nostalgiaair.org forum.

[DonaldSmith]

Available at nostalgiaair.org. Go to "Resources". Very clear and legible.

602 is Colonial Radio 671A. 3 page pdf.

802 is Philco Radio & Television C4608. 10 page pdf.

Vibrator and transformer circuitry is similar.

The nostalgiaair forum also answered my questions. There were 3-pin as well as 4-pin vibrators. Some radios were wired to accept either. They also have a way to "reform' the vibrator with 120 volts in series with a 40 to 60 watt bulb, across the driver coil, to clean the points. I'll have to try that. I have the can off, so I'll be able to see the arm vibrate and contact the points.

I'll be careful with the 120 volts. Also, I know that there will be high voltage in the radio when it works. And capacitors can store electricity. Large capacitors have been known to kill people.

[DonaldSmith]

(No snide remarks, now. Another perfectly good word twisted beyond recognition. I'm talking old car radios.)

I had the case off the vibrator, so I could see how it's supposed to work.

With 6 volts to it, an arm would be pulled one way, opening one contact and closing another. Closing the second points is supposed to short out the coil, allowing the arm to go back, but it didn't.

Following suggestions on the nostalgiaair site, I connected 120 volt house current through a 60 watt bulb in series, to the somnulent vibrator. (That means "sleeping," to you in Rio Linda.) The alternating current had that arm humming while it burnt the crud off the second points.

I tested the vibrator with 6 volts, but at first it would not sustain the motion. After a few more treatments, it began to work again.

I've got together an order for capacitors and tubes (and dial cord) from Radio Daze. Anyone done business with them? Less than $40, plus shipping, and the wife is amenable (that means she'll go aong with it) but I 'm imposing a 24-hour waiting period. Anyone have radio dial cord lying around? I can get 25 ft for $3.50, but I won't need that much.