Refurbishing Factory Premium Sound

[gadget73]

No bulb on this style. There is a slightly newer one that does have a backlit display though. Those are an LCD with black digits and a green lamp behind it. Thats the 6 memory radio with the knobs.
**edit** this one


These are what is called a VFD, a vacuum flourescent display. It actually runs on 40 volts or so for the plates and about 2 volts for the filament. Its a vacuum tube, or related to a CRT.

anyway, what happens is the flyback transformer that creates the high voltage inside dies. Its on a board down inside somewhere. In theory its an easy fix, you replace the transformer on the board. The problem is they don't seem to exist anymore so I have no idea where you get one. I've got one that became a parts radio for exactly the same reason. Pulled the transformer out and it ohm checked open.

[Mainemantom]

Interesting info Gadget. Not surprised that the parts to fix the VFD are not available.

[Kodachrome Wolf]

I've got the early style VFD and later style backlit style AM/FM stereo units. My early unit also has suffered from the failed transformer issue (amongst some other wonky issues), but the regular illuminated components always worked.

[87gtVIC]

No bulb on this style. There is a slightly newer one that does have a backlit display though. Those are an LCD with black digits and a green lamp behind it. Thats the 6 memory radio with the knobs.
**edit** this one


These are what is called a VFD, a vacuum flourescent display. It actually runs on 40 volts or so for the plates and about 2 volts for the filament. Its a vacuum tube, or related to a CRT.

anyway, what happens is the flyback transformer that creates the high voltage inside dies. Its on a board down inside somewhere. In theory its an easy fix, you replace the transformer on the board. The problem is they don't seem to exist anymore so I have no idea where you get one. I've got one that became a parts radio for exactly the same reason. Pulled the transformer out and it ohm checked open.

thanks for the information.

any idea what it looks like and what its values should be. I work in a place that used to repair electronic tv and camera equipment dating back to the 70’s. We have tons of little electronic components around in organizers. I am not well versed in this stuff though so some guidance is necessary. If I would somehow find a stash of them that would be pretty neat to repair some hurting radios.

[gadget73]

These are some scans from the service manual. I'd be lying if I could tell you where this physically lives inside the unit, but I don't remember it being all that difficult to access.

Entirely possible that a part from a VCR would get the job done, or maybe the entire board could be dumped for something else. I don't think it matters a ton, so long as it outputs the correct voltages to the rest of the circuit. Also not completely impossible the transformer could be re-wound. I never dug into it quite that far but its not large and I suspect the wiring would be fairly fine in there.

[87gtVIC]

Thanks Thain.

I printed them all out and will have to give it a good long time to soak in. Appreciate it.