1956 Buick with a Delco Sonomatic #981707 I had a local guy replace the capacitors, the vibrator, but now there is smoke coming from the transformer area, under the chassis. He is not willing to do any more work, as he is not familiar with these radios. The vibrator was bought used but tested and was working, 3 prong 12V. Before any work was done, I was getting a constant volume buz sound. I came across this guy from a local car club, I knew about his limitations, (not being familiar with car radios) but all I wanted was someone to check the tubes and replace the capacitors. The radio powered up, volume worked, found a station, but with in a minute it started smoking, white smoke with a foul smell coming under the chassis by the transformer and vibrator area. I turned it off and removed it from the car. If anyone is willing to take a look at it and possibly go over it, align it and test it properly, please let me know.
Thanks
66R

Smoking is of course not good for your car radio

Sorry gallows humor.

I would not think a stuck vibrator would not burn up a transformer. A short of some kind should blow the fuse.

It could well be just an exploded capacitor. It could be a polarized capacitor was put in backwards. Capacitors are more inclined to foul smelling white smoke, different from a burning transformer. Usually preceded with a popping sound.

I notice in the schematic for the Delco radio in my 54 Packard there are no polarity sensitive components in the 6 volt side (noting the Packard is + ground). I don’t know which side is ground in Buick but people often assume all cars are neg. ground.

Jim

The later Buick radios had non-synchronous vibrators, so they are not polarity sensitive. My guess is, either the electrolytic capacitor failed, or the buffer capacitor shorted out, burning out the 15k resistor in series with it. If the repair guy missed changing the buffer, or used a low-voltage replacement, shame on him! That's one of the most troublesome components in any 1932-58 car radio; right up there with electrolytic and audio coupling caps.

I'll be very happy to service your radio on my bench here, but remembering I'm in business there's a price.

However if you want to do some troubleshooting yourself, and have a test bench to do it with, the very first step is to remove the vibrator and rectifier tube, then with a high voltage power supply, apply B+ voltage to the rectifier output. Bring the voltage up slowly and measure the current. You should be able to provide 230 volts with no more than a couple milliamps of current. If good, apply 6 volts to the tube filaments and see if the radio plays. If so, we know the problem is in the vibrator/transformer area.

WITHOUT a test bench or test equipment, you can certainly make a visual check to see what was done. Buffer capacitor? This is a cap in the transformer secondary; look for it under the rectifier tube. I don't have the schematic in front of me but it's generally around .0068uf, 1600v. Is it the old waxy thing (maybe tripled in size!) or is it a new ceramic? Or is it missing entirely -- I've seen that too. Then the electrolytic. This is a round metal can which typically has three caps in the can, with the case as common ground. I replace these with new cans, but most don't have the resources. You should see new electrolytics underneath. But the kicker: did the guy DISCONNECT the can, or is it still in the circuit? They leak; they short, they pull current; they should be removed or at least totally disconnected. If you see any of this, it's the FIRST thing to deal with.

I really, really, really hate saying this, but as everyone knows there are good mechanics and there are idiots who can take your money and ruin your car. Same with the radios; just because somebody sez he did a recap doesn't mean he serviced your radio properly. If the guy told you he's not sure what he's doing, well, I give him credit for honesty but that certainly makes me suspicious of the work done. I don't know your level of expertise, but if I can help you via this forum that's wonderful, and my advice here is FREE.

66R welcome to the forum.

I may have the power supply parts available for the 56 Buick radio. I will need to check my box of old radio parts in the basement. If anyone is able to help with the radio repair, contact me about these parts....


Just after High School I purchased a 56 Buick radio from the junk yard and removed the 12 v power supply parts and installed a 120 volt supply in the radio and ran it in our house and connected to a large speaker box. Anyway, I think I saved the parts for the 12 volt supply. I may have the vibrator and transformer etc. Note that the rest of the radio is long gone......



G.

Here is the schematic for 56 Buick model 981707:



The radio was working, so it’s unlikely that the vibrator is at fault. More likely are the components mentioned by Tim Tress: 15K 1watt resistor (#53), or .007 mfd/ 1600 vdc buffer capacitor (#32). .0068 mfd. at 1600 vdc is a suitable replacement for the buffer. Delco recommends a carbon composition resistor for the 15k 1 watt unit.

I also have some parts for this radio, so between philconerd (G.) and other helpful forum members and I, we should be able to help you get your radio up and running again.

Hello, I found this thread from a google search and also have a 1956 Buick Sonomatic radio I would like to get working but I have zero previous radio experience and very little electronics experience.

I purchased a 1956 Buick two years ago in rough shape and it was missing the radio, this year at a swap meet I found and purchased a Sonomatic for $10 in as-is condition.

Last night I tried wiring it up for the first time using a computer power supply to give me the 12v. Looking at the front of the radio on the left there is a wiring coming out of the radio I assumed was positive and I attached the negative to one of the mounting bolts. When I turned the radio on the light came on and it made a buzzing sound, not static, buzzing. I assume this is the vibrator I have read about operating. When I change the volume knob the buzz stays constant.

Any ideas what is wrong or what is the next step to find out what is wrong? Where does the antenna attach?

Here are some pictures of my radio:

Front view: http://i97.photobucket.com/albums/l222/ ... 021901.jpg

Right View: http://i97.photobucket.com/albums/l222/ ... 21900a.jpg

Left View: http://i97.photobucket.com/albums/l222/ ... 021900.jpg

Thank you,
Ryland

On left side view, antenna goes in small hole with a bolt above and below the hole (Motorola type connector). Radio will not receive any stations without an antenna. For temporary testing purposes, any 3 foot length of wire will do.

Thanks! Once I added a makeshift antenna it worked! Still buzzed pretty loud but heck it worked! Not bad for a $10 radio.

Thank you,
Ryland

You should replace the paper capacitors before using the radio. The buzzing sound from the radio (with the volume turned down) is the vibrator running, which is part of the power supply in 1930s-mid 1950s radios.

When you get the radio recapped, and are ready to install it in the car, you might consider replacing the vibrator with a solid-state model; they are silent.

The solid state vibrator is not silent, but it is quieter than the mechanical type.

My suggestion is to indeed replace the vibrator, but don't install it until you're finished rebuilding the radio. Installed properly the new ones last forever, but they are easily damaged if reversed polarity or improper spikes are present. Mechanical vibrators only have an expected life of 18 months of regular use, but it's hard to zap one with a meter probe. I personally use mechanical vibrators for testing and troubleshooting, but every radio leaves the shop with a new solid state type.

The question about the hum, is it a mechanical hum from the vibrator, or is there a loud hum coming from the speaker? A bad electrolytic can give you hum. Electrolytics should be replaced anyway, as they are very old and will dry out over time. Even if it tests good, it can go bad at any time.

Ideal -- replace the electrolytic with another FP type -- three caps in a metal can with twist tabs mounting it to the chassis. AES offers a two-cap FP, 20/450-20/450 for about $30. The third is generally a 20/25; these are very small and can be mounted near the output tubes. In lieu of using a new FP, you should still disconnect the old cap while using new electrolytics underneath the chassis. I do this by removing the old FP, soldering a terminal strip where the FP was, and connecting all the wires and caps to the terminal strip. Yes this is a job which I hate, as it's a fair amount of work and it's not easy to get the chassis hot enough for the solder to melt (even for removing the FP). But it needs to be done.

Then, all of the wax/paper caps need to be replaced. Do one or two at a time; two reasons. First, you'll often notice an improvement in performance -- a little clearer, a little more sensitive, etc. Second and more important, if for some reason the radio STOPS working, you know what to check -- the work you just did. After working on these radios for many, many years, I still make a practice of doing this.

Indeed there's some work to be done, but once you're finished you'll have a radio you can play every day without reservation.

I have a soft spot for these so I will pop in here.

The old mechanical vibrators do have a life span that is usually shorter than the tubes. They worked fine for years when these radios were new. The capacitors are the bigger problem and when the ones in the vibrator circuit start to go you get arcing at the contacts which eventually kills the vibrator.

The 0Z4 rectifiers don’t last forever either.

The radios are a straight forward design with inductive tuning which is more stable and robust than using an open variable capacitor. Your radio appears to have the standard mechanical push button tuning not the automatic type and these are more robust. Some of these radios had complicated automatic tuning which will require some clock work skills to repair.

You may hear a faint hum from the mechanical vibrator as it is vibrating however you should not hear any hum in the audio.

As the painful part of working on a car radio is installing it in the car, you want to do a quality restoration and do everything before you put it in the car.

There is usually a heavy wire often with a fuse holder which will be the power for the radio. There is a lighter gauge wire for the dial lights. The antenna cable has what looks like an oversize inside out phono-plug the plugs into the radio case I assume that thing up on top.

The radio in my 54 Packard runs on 6 volts with a positive ground. It works fine and sound quite good with the 6V6 push-pull audio outputs. I leave it turned on and it comes on when I start the car. I can barly hear the vibrator and never after the radio has warmed up.

I found the service lit here on the forum.

Jim

Is there a 6 volt version of the solid state vibrator?

May as well replace the 0Z4 with a couple of diodes at the same time eh?

Jim

For many years AAR has built Solid State Vibrators that intentionally made a small amount of buzz. I've asked Dan Schulz about it, his answer is that "there are ways to do it" without elaborating.

The newer versions, the ones that are so light that they feel like an empty can, I've noticed they are quieter, and vary -- about one out of three is silent, the others have a very faint buzz.

Indeed there are 6 volt versions available. Many types HAVE been discontinued however. The ones that are still available are the standard three-and four-pin, the four-pin version with a rectangular pattern instead of square, and a couple others. The discontinued types are the ones that fit only one or two models and nothing else. Whenever I get one of these radios (which is not often) I replace the socket and use a standard type.

On the few solid state vibrators I built up with germanium transistors you could hear a very soft buzz from the circuit. In the audio section of the radio with no antenna, the buzz would be a very faint version of the 400 Hz buzz you'll hear on an aircraft PA system when there's nothgn being broadcast.