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On 17 Mar 2018 13:45:22 GMT, Peter Wieck
wrote:

On Saturday, March 17, 2018 at 8:02:39 AM UTC-4, wrote:

On a side note I have a Counterpoint 3.1 pre amp and the input
selector switch oxidize's over time causing distorted sound. It has
silver contacts. I have tried TV tuner cleaner and DeoxIT with mixed
results. I have actually taken the switch apart and hand cleaned the
brushes but the problem comes back. Any ideas, any one, for a long
terms fix?

Silver is problematic and problems with it are generally of local origin. To keep in mind:

a) Of all the room-temperature conductors, Silver is best by a long margin, copper is next, gold a poor third in that group.
b) Gold does not oxidize under normal conditions - but if the connections are poorly plated, or an alloy plating is used, they will be worse than plain copper or spring-bronze, or even tin-plated spring bronze. The cynical part of me will suggest that anything coming out of China into the audio market will *not* be good. On the surface, it is impossible to discern the difference.

Silver is attacked most commonly by sulphur. Source being fossil-fuels, especially coal or heavy oil, or *Heating Oil*. Secondary sources being low-grade kerosene, rubber and food processing plants, paper making and similar. Back in the day, the "Staff" were forever polishing the silver as mostly bituminous coal (burnt for power here in the US) was used for heating, generation of "town gas" for lighting, and the clinkers were used as ballast and instead of gravel for paving.

Ozone will degrade rubber products, wherein fairly large quantities of sulphur are used for vulcanizing. Some hair products - conditioners, setting gels and similar also contain significant amounts of sulphur. Then, eggs.

Put simply, if you are in an environment rich in sulphur compounds, anything silver will go 'black' quickly. Now, in the Better-Living-Through-Chemistry department, this issue with silver has been understood for about 100 years. And various solutions for various applications have been developed. In your case: https://silverguard.com/collections/...tarnish-strips Would be a suggestion. If you put it inside the unit as proximate to the switch as possible, ideally with some contact to anything touching the silver, if not the silver itself, it will prevent oxidation/sulphation for some period until the volatiles disperse - a year or so in any case.

Peter Wieck
Melrose Park, PA

Don't think I am in a rich sulfur environment, at least not from an
industry stand point. Thanks, will give those strips a shot.

Bill T