Cleaning the blades of an am tuner.

[Brett a]

So, I think I might have made my first mistake in my newly developed obsession of working on really old equipment. I sprayed the tuning blades of my '46 Zenith tabletop with Deoxit. It worked pretty good before I did anything to it, but i couldn't resist trying to make it better (next time, I'll resist)

After I sprayed it, it no longer tuned at all, just static. Now that it has dried overnight I'd say it has about 60% of its ability back.
What should i do now?
What should I have done? (Leave it alone would be a good guess)

[radiotvnut]

I'm sure what happened was that the deoxit de-tuned the oscillator and RF trimmers on the tuning cap. I have made this mistake before. You might try blowing the tuning capacitor with a hair dryer for a few minutes. I did that once and it cleared up the problem. Otherwise, you'll have to re-align the radio.

I have cleaned dirty tuners by spraying a small amount of control cleaner in the tuner and then running heavy paper between the plates. I've used this method on noisy tuners that wouldn't budge otherwise.

[marty59]

Some better ways to clean a tuning cap is with "canned air" or low pressure compressed air. Felt pipe cleaners are effective at loosening up the initial dirt/dust followed up by the air. Sometimes, it's best to remove it to clean but not always feasable or necessary.
Be careful not to jam or force anything between the blades, as that will change it's alignment and cause you other problems!
But for you at this point some air may help as either some cleaner/residue may be providing some conductance, especially where the alignment screws are. Also, if you take a meter to the movable blades or the shaft and the body you should see zero ohms/short. The stationary side shoud be isolated from the body.

[Brett a]

Thanks
You guys make AK an amazing resource.

[Arkay]

You could try cleaning it with an absolutely NON-residual cleaner, such as pure acetone, followed by the blow drier treatment. DeOxit leaves behind a thin protective film, and this would be enough to detune your tuning cap. Remove that thin film, and all should be well again.

[Reece]

If all else fails, you'll need to clean out the mica trimmers on the side of the tuning capacitor. They may have residue from the "power cleaning." Problem is, if you take those apart, you lose your alignment. Method: tighten each trimmer screw, carefully counting turns down to the last quarter turn, all the way. Write down the number. Then take the screw out. Clean the trimmer plates and the mica insulator with a cotton swab and alcohol. Allow to dry. Reassemble turning the screw tight, then back the screw out per the number you wrote down. You'll be close to where you were but will need to tweak the alignment.

Reece

[Old1625]

Ditto on the mica-compression trimmers. They cannot be contaminated by lubricants, but must remain dry to do their job.

When cleaning the rotor/stator assembly of a tuning gang use compressed air only. Be sure to apply the jet of air straight on the edge rather than at an angle to avoid bending the plates, which can lead to rotor-stator contact. Staticky action of a tuning gang when moved means the ground brushes at each partition that ride grooves in the gang shaft should be hit with DeOxIt. But application should be sparing, and to the brushes only. Lavish application of any tuner lube to a tuning gang will only lead to heartache.