A friend has one and wants me to check into an intermittent problem. I suspect the vibrator. Anyone know what type it takes? i.e. 3 pin 4 pin 5 pin 6 pin?? Also what's the rectifier? is it an 0Z4?

That Chevy radio takes the "standard" 4 pin 6 volt vibrator and uses a 0Z4 tube as the rectifier.

All gm's from the 30's & up are negative ground too Bob.

billn

If you can hear the vibrator it's probably not intermittent. Replace the 0Z4. If battery voltage is low it may not start. Could be intermittent even with proper voltage.

You can replace an 0Z4 with diodes. The metal tube comes apart easily and there is plenty of room inside. If using diodes add some resistance (47 -100 ohms) in series with each side.

Sorry, startinagain, but that information is incorrect. Most Chevy & GMC trucks in that period are positive ground, as are some Chevy cars as well as Olds, Pontiac and most of the "orphan" brands that utilized Delco radios, at least when utilizing 6 volt systems. Kaiser, Studebaker and Packard are examples that come readily to mind. 12 volt systems in GM cars are, to the best of my knowledge, all negative ground. Buick was always negative ground. Cadillac used positive ground electrical systems until the end of the 6 volt days.............GREG

EDIT.....I also put my money on the OZ4. Tricky little buggers............

If I may make a suggestion--------You may want to re-check your facts and maybe revise part of your statement.

A battery ground chart is here:

http://www.radiosforoldcars.com/vibratorsF.htm

Since these folks make solid state vibrators, I trust they would get the polarity correct, otherwise they would have a bunch of blown S.S. vibrators on their hands.

Was referring to most of the GM car radios as being negative ground since the subject topic is 50 Chevy radio.

It seems that early Cadillac used pos ground.

As Meade pointed out refer to the vibrator chart. Thanks Meade.

billn

Thanks Meade, you saved me the opportunity to be called grouchy again

Carl

Sometimes vibrators need a shock to start; like cycling power.

Just how intermittent is the problem? Can you replicate it on the bench? Listen to the vibrator and check the voltages.

ALL 6 volt Chevys were negative ground. Not so for all GM vehicles. For example the Chevy and GMC trucks from 1947-53 had the same radio except for the dial, but the Chevy was negative ground and the GMC was positive. Cadillac was positive ground until WWII. All postwar Caddies are negative. The vibrator for your car would be a 1015-N.

There are a number of things that can give you an intermittent problem on these radios. Make sure that 3-pin connector from the radio to the power unit is solid; these can give you grief. So can dirty tube sockets.