I noticed something on an electronic Clock-radio recently - as on my previous clock-radio, adjusting the volume control introduces static, and jumps up and down in volume. I assume this is some sort of potentiometer knob in the circuit, is this possibly repairable as a single component? What causes this puzzling glitch, dirt? corrosion?
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\$\begingroup\$ oxidation and poor gold plating with the surface friction wear on 1-2u" of gold plating takes its toll with cost-reduced parts wiping on carbon film surfaces. In some cases the carbon comes loose off the film and perhaps other cases it could dust accumulation \$\endgroup\$– D.A.S.Commented Oct 20, 2016 at 2:15
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\$\begingroup\$ Here's my guess. As the wiper moves, it is sliding along the surface of resistive element. With particles such as dirt or dust that lay over the resistive element, when the wiper moves over it, it isn't contacting with resistive element as well. This means the wiper is bumping around and that changes the resistance across the potentiometer. Try a new untouched potentiometer and see if it is as bad. \$\endgroup\$– Bradman175Commented Oct 20, 2016 at 2:17
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1 Answer
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It's because some consumer devices are built down to a price and as such usually use the cheapest components available. In the case of a clock radio's volume it's the rotary thumbwheel potentiometer behind the volume control. A little bit of contact cleaner (electrical, not optical) will improve the situation, but at the end of the day the pot is a piece of garbage that just won't last a long time.
answered Oct 20, 2016 at 2:10
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1\$\begingroup\$ They are often slider pots, but the same still applies. \$\endgroup\$– user16324Commented Oct 20, 2016 at 9:48
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1\$\begingroup\$ Oddly enough, all the ones I've ever had or seen are thumbwheel. \$\endgroup\$ Commented Oct 20, 2016 at 13:12