"Alan" wrote in message
...
Hello,
I'm a part time hobbyist, with a passion for old multi band radios.
Yesterday, I picked up a Telefunken Concertina 3520 for $10 from a flea
market....I always liked the 70's styling on these.
Took it apart, and it's in good condition, except the tuning string is
broken (easy to fix), but the tuning cap is frozen.

Now, this cap is unlike any other ones I've seen...it seems to have other
gears and things in and on it...almost a motorized tuner, but not
quite...it
won't budge at all...the tuning know has the nice 1 lb flywheel weight the
end...a google search indicated that the tuning capcan seize, but this one
seems more jammed than rusted....as I said, it's in mint conditon
inside...it's just that I haven't been able to move the capacitor.
Below is a link for the picture of this cap....anyone have any ideas?

http://img.photobucket.com/albums/v2...rsonal/cap.jpg

To reply, remove remove from the email .

Thanks



I'll guess the capacitor's lubricating grease has dried up and hardened.
Try spraying some penetrating oil into the bearings in the front and back.
WD-40 is probably OK, but there are more agressive penetrating oils
available at auto parts stores. I've never had any problem from a
penetrating oil residue in the electronics, but I suggest you stuff rags
under the cap to keep the oil from dripping around inside the radio. Give
the penetrating oil plenty of time to work, at least a few hours. Spray it
in a few times in those few hours.

If the lock up is really stubborn, you may be able to help free it up if
there's a removable ball bearing on the back side of the cap. Remove the
lock nut and the bearing simply screws out. There's a single ball bearing
in there, be careful -- you don't want to lose it. Resetting the bearing is
simply a matter of getting the movable plates centered as well as possible
between the fixed plates, but I suggest leaving the rear bearing alone,
except as a last resort.

The bearings can be regreased with some grease and a toothpick.

Cleaning the oil off the capacitor's plates is probably a good idea. The
oil won't make much difference electrically, but it will hold dust. A small
brush and some rubbing alcohol should do the job.

The frame of this capacitor is made of pot metal. Unfortunately, pot metal
doesn't always age well, especially when exposed to wide temperature
extremes, such as might be found in an attic. Inspect the frame carefully
for cracks, or swelling or a "crumbly" look. Also, make sure there isn't
something physically blocking the capacitor's plates.

Those gears in the cap are a gear reduction drive. It probably turns one
full turn at the shaft for a half a turn at the capacitor, or something like
that.

Frank Dresser