Electronics > Repair

Cleaning decade resistor box contacts (alternative to DeoxIt?)

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I have a precision decade resistor box which gives me very inconsistent reading, truly a big problem given that the lower decade has 0.01ohm steps.
The contacts are black from oxide and even if I already tried two times I can't clean them with the procedure in the datasheet. It says to clean the contact with ether and microfiber cloth and then applying three drops of ricin oil.
I got some improvements, but this procedure does not remove the oxide at all, and the lower decade is still useless with the readings that jump all over the place.
Is there another safe way to clean this type of contacts?
I've read many times of the wonders of Deoxit but here in Italy it's impossible to find and importing it would cost more than what i paid for the resistor box.
Do you have any experience with WD-40 contact cleaner? How does it compare to Deoxit? I also need to clean the binding posts, which as you can see are all black and corroded.

Of course for my measurements i did not use the corroded binding posts, but i connected the test leads directly to the resistors below

It should be non-conductive and non-corrosive and leaves no residue. I do not believe WD40 is good here, especially with precision equipment such as your case.

I have been using with success Motip Dupli Contact Cleaner which should be widely available in Italy.


Try a smear of Vaseline (seriously).

I think it's a mistake to use chemicals.  I would, instead, polish the surfaces until the oxide is gone.

Many a decade box has been ruined by various chemicals.  Alcohols, reducers, lubricants.  Especially for low resistance boxes.  High quality switches are not enclosed and cleaning is possible.

Stray Electron:
  For circuit board contacts (fingers), I have used denatured alcohol. I'm told that they add a small amount of kerosene to "denature" the alcohol to stop people from drinking it. The alcohol soon evaporates but it seems to leave a very small amount of oily film (kerosene?) on the contacts and I notice that the boards slide in and out of the connectors much easier and seem to make more reliable connections.

  I think that WD-40 is also mostly kerosene but with some drying agents added. So it might work just as well.


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