cleaning a dirty tuning capacitor

[plaka78]

Hello Folks

Can anyone give me some tips on cleaning a dirty tuning capacitor with light corrosion

Tony

[Mike Phelan]

Tony
Have a look here.
A search will get you quite a few threads on this subject. Denending what sort of capacitor it is it is usually necessary to dismantle it to clean and lube it properly.

[Ben_Dijkman]

I know people who " burn " these capacitors clean by give a relativ high voltage /amperage to the capacitor
The dirt is a low risistance shortcut between the plates and so becomes the only way tru and will burned away.
I've never done it myselves.The results I've read seem to be quitte good

[Skywave]

Yes, this is a question that I have frequently asked myself; the comments in the earlier Posts are useful.
However, I have occasionally wondered if an ultra-sonic bath would be OK for this job. Not that I own one - yet - but perhaps one day . . . just one day . . .

Any thoughts on this, chaps?

Al / Skywave / 20-07-07

[Mike Phelan]

That will certainly clean it, Al. It will remove any lubricant, though, so you'll still have to take the rotor out for a proper job.

[Skywave]

Thanks Mike.
Lubricant, removal of: of course! I hadn't thought of that!

However, doing as you suggest is not (well, to me, anyway) an "informal" task - so suppose I simply add fresh lubricant to the bearings after such cleaning - thereby (hopefully) avoiding the hassle of a complete strip down and re-assemble? Or is this not practical? Would something like 3-in-1 oil be adequate? Or should I use some sort of special conductive grease?

As you can tell, I don't have much experience in doing exotic things like dismantling traditional moving-vane variable caps - I sense that this sort of activity will lead to grief: lost ball bearings, misaligned vanes, etc. and that all-too-familiar feeling of "why, oh why did I start this?

Regards,

Al / Skywave / 25-07-07 //

[Mike Phelan]

Hi Al
I would use grease, rather than oil, on the usual sort of tuning gang (ball race at the front and single ball at the back). There is quite a bit of pressure on these bearings and thin oil is not really adequate. 3-in-1 also tends to creep everywhere, as it is intended to.

It is not too difficult to remove the rotor; just make sure it is wide open (minimum capacitance) so the vanes are not caught, and do the job on something like a tray so the balls don't fall on the floor, never to be seen again.

It's a good opportunity to clean and tension the earthing springs.

When you reassemble it, close it up and adjust the vane spacing equally by eye with a loupe; it may or may not need RF realignment, but that's no big deal.

[russell_w_b]

Originally Posted by Skywave

However, I have occasionally wondered if an ultra-sonic bath would be OK for this job. Not that I own one - yet - but perhaps one day . . . just one day . . .

Any thoughts on this, chaps?

Al / Skywave / 20-07-07

I have used an ultrasonic bath to good effect on other components. Even if you don't have the correct cleaning fluid, de-ionised water with a drop of methylated spirits in does the trick. Or if you have a small amount of cleaning fluid, put the cap. in a sealed polythene bag in the DI tank-water.

Have you considered removing all non-metallic parts and boiling it in water for twenty mins, followed by immediate lubrication? I mentioned in another post that I've had success with this method on telephone dials. Different metal, though, so take care...