Packard Forum Index » V-8 (1955-56)

How cool is this video? Enjoy.

youtu.be/7P9jHBDT-y8

Interesting. I don't recall the Packard model needing the reset in the middle but maybe they do. It would be nice to know of a proven way to restore the favorite station select tabs controlled by the pushbuttons. Those tabs get dirty or oxidize somewhere and lose connection. Contact cleaner doesn't work half the time. The finger contact that is supposed to stop the mechanism as it runs over an active tab doesn't connect so mechanism goes past the station. Sometimes it will cycle continuously unless the button is released or another selected. Wonder if the FM adapter he mentioned completely eliminates those.

As I recall, the buttons were reset by manually tuning to a station, then pulling out the button all the way and pushing it back in. Is this what you meant? In any event, having the mechanism clean and lubricated is important to proper functionality.

Yeh. Im not sure what Howard meant either. On the wonderbar in the clipper there was a door that flipped down and the little red indicators were "set" to position- then when the individual buttons were pushed the tuner moved to the preset. This was mechanically operated. Then the top "wonder bar" could be pushed and any preset button that was "in" would pop out and the dial would "seek" just as shown in the vid. I was told if these radios were recapped they would find and play am. There is a sensativity adj fine tune on the dash as well as a screw on the radio for adj correct?
Also- all are saying there is no issue to swap to neg ground but if I recall the wonderbar delco in the 55 said " POS GRND" on a tag on top. Will these be damaged on a neg grnd swich?

Ah, I had forgotten about that and I can't view videos.

Also going from ancient electronics experience (I earned my first dollar as a kid fixing a radio rather than mowing a lawn!) and possibly-poor memory, switching to negative ground shouldn't damage the radio but it also may not function if reversed. However, the radio circuitry itself runs on AC that is created by the vibrator and transformer and I can't imagine how reversing the polarity would make it work any differently unless there are some capacitors that might also have to be reversed. If you have a modern electronic device in place of the original mechanical vibrator, it would have to be replaced but otherwise it should be okay.

That is the way setting stations in the mechanical radios work -- same idea but different method in the Wonderbars.

On mechanicals there is a flat paddle like affair connected to the tuner mechanism. It rotates as the needle moves across the dial so as the needle progresses the paddle is in a different rotation.. Each button has a mechanism that can push against the paddle. When you pull the button out to set a station a friction point on the mechanism is released and allows it to rotate. As you push the button back in the mechanism attached to the button pushes against the paddle and takes the same angle and matches the rotation the paddle has at that particular station. When the button is fully locked back in position the mechanism is locked too and keeps the particular angle. The next time you push the button the attached mechanism forces the paddle to take the same angle it was set when the station was "programmed" so tuner goes back to that spot.

The Wonderbar has individual tabs for each button located under the dial. Those are positioned for each station. When a button is pushed in it disconnects the automatic signal seeking electronics and provides an electrical signal to a particular tab. There is an extension to the needle connected to the electronics and as the needle moves it slides over the tabs and makes electrical contact with each tab. When it finds one that is electrically active it senses the voltage or current and sends a signal to the relay which immediately stops the motion at wherever the tab is located on the dial. The problem arises when for whatever reason -- oxidation, damage, looseness, ??? -- the tab becomes "disconnected" from its button so the sensing of one that is electrically active never takes place. When that happens the mechanism keeps moving and the only way to stop it is to release the "dead" button to put it back into automatic seeking mode.

Here is the Wonderbar with exposed tabs. At the end of the arrow you can barely see the extension of the needle which slides over each tab to make electrical contact.

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I see. So the presets are electrical not mechanical. Got it. And the power unit on the right has the vibrator and works on ac I know but are you saying there is no DC input to the radio head unit in the center of the dash? I ask because the antenna is grounded to the car so the outer shield is + on a pos grnd car which makes the chassis of the head unit +. So are you saying there will be no issues to swapping the chassis to neg? Why would delco specify pos grnd on the 55 wonderbars?
Just asking cause I know a late model radio with Neg chassis can be mounted in a + grnd car if its chassis is isolated and function correctly with cd and usb ans memory stick- until u try to plug in an antenna.

Good point about the power antenna but the antenna connection itself should work either way as power or polarity has nothing to do with it. The electric motor, though, is DC and may work the opposite so it will probably be necessary to reverse the wires on the switch or at the motor to make it go the direction expected.

I have a 55 schematic but don't have a 56 Wonderbar schematic to see if there is any difference in polarity of caps vs the 55 unit. It would be interesting to compare closely and see what if any difference there is. I know some radios do not really care because the electronic components are referenced to voltage and ground internally and don't care about any external influence. That can be verified by all the cars with batteries that accidentally get switched by mechanics or whatever and the radios keep right on working.

The radio works essentially all on DC. 12v is fed to the tuner unit into the on/off switch and also directly powers the dial light, solenoid, relay and tube filaments. The switched 12v is also fed to the speaker and power unit. The vibrator takes that 12v and starts oscillating. With the use of a center tapped transformer, the vibrator energizes one half of the transformer primary and then the other half in rapid succession. The vibrator is running at 115cycles so with the transformer primary alternating sides it starts mimicking AC. The secondary side of transformer feels the "alternating" primary and puts out a voltage of 280 VAC. That voltage is fed to a rectifier tube and comes out as a positive 255V DC which is fed to the rest of the radio.

As that video explained, there is no motor in the unit. When the needle moves, a spring pushes the mechanism and thru some gears and a flywheel the speed is controlled. There is a relay which either releases a stop to let the flywheel go or shoves the stop into the flywheel to block the rotation. When the mechanism reaches its end a switch is tripped and a solenoid pulls the mechanism back and compresses the spring again -- sort of like the way the clock winds itself.

There is wonderbar radio information on this site for 56 57 delco wonderbar radiopackardinfo.com/xoops/html/downloads/1957_484649_RadioFacts.pdf