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b139b 22nd January 2008 11:35 AM

Repair scratchy switches
I am not so good in english, but i hope you will understand...

I have a harman/kardon hk670 Receiver from 1979. It works well, has a good sound, but all switches and pots are bad,
making dropouts and scratches. They have been cleaned during the years with WD40, but it does not help much anymore.
Now i want to unmount the mechanical parts and will try to clean them in that stuff withch
you can make silver shining again (household silver shine stuff)?

Has someone tested this? Other tips?

What can be done with potmeters?


Bobken 22nd January 2008 12:26 PM

Hi Christian,

Your English seems pretty good to me, and is more understandable than a lot of lazy posters whose native language is English.

What I would suggest here is to try some "Deoxit" made by Caig Laboratories, as this is by far the best material I have come across for this purpose in well over 30 yrs.

It is quite different from other contact cleaners, and I personally would never use WD40, as it is not intended for this purpose, anyway, and it leaves residues which are not desirable for good sound.

The Caig products are quite 'universal' in their application, and they do have another product specifically formulated for rotary pots etc., but Deoxit will be fine for this, and it will save the additional costs of buying several different products. These products are a bit more costly than most other cleaners, but very little is needed and a small can will probably last you a lifetime, unless you do restorations for a living.

Having used this product and recommended it to others (including on this Forum) no-one has ever suggested that they were anything other than delighted with its beneficial effects on all kinds of ancient (and new!) contacts, plugs, sockets, switches, & potentiometers etc. If you have a look at Caig's website, you will learn a lot about their products, and see that many manufacturers use their products in highly critical areas like aero-space, telecoms, and anything where metal-to-metal contacts are involved.

Many high-end audio makers use and recommend it, and if you allow some Deoxit to evaporate in a small dish, or whatever, you will end up with another product, Pro-Gold (was what I last saw it called) as Deoxit is the same Cramolin-based product, but heavily diluted down to merely 5% in a strong cleaning agent.

Finally, you will probably find that you will be able to effect this work without any (or much) dissembly of components, which is another bonus. It has tremendous 'creeping' properties, and will find its way into switches etc., usually without any need to take them apart. In my experience, if Deoxit does not provide a satisfactory result, it is due to the fact that the component concerned is beyond restoration by any other similar means.


b139b 22nd January 2008 07:50 PM

Thank you for your nice reply.

Seems that Caig Laboratories have no distributor in Norway. I have sent mail to Sweden and asked them if they sell to Norway.


Bobken 22nd January 2008 08:18 PM


Originally posted by b139b
Thank you for your nice reply.

Seems that Caig Laboratories have no distributor in Norway. I have sent mail to Sweden and asked them if they sell to Norway.


Hi Christian,

You are welcome, and I am sure you will not regret using this cleaner/enhancer. I have used it for many years in all kinds of repair/restoration jobs, and always use it on new contacts too, as it improves the sound.

If you are unlucky locally, PartsConneXion in Canada sell this and will mail it to you, I am sure.


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