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Old 23rd Jan 2020, 1:22 am   #8
JimMac53
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Join Date: Apr 2009
Location: Naples, Florida, USA
Posts: 255
Default Re: Potentiometer in Andante 1462. Original?!?

I watched the video. That is 50Hz hum. The hum comes from the voltage induced in you from the 220vac 50Hz in your house. The 220vac wiring in your house creates an electromagnetic field - much like the primary in a transformer - and it induces a voltage in you (you can see this on any oscilloscope). You are like the secondary of the transformer. It's very low voltage, but more than enough that once amplified, will sound loud in the speaker.

Some of this might go away if you physically install the pot in the chassis, but I suspect the center shaft of the pot is either connected to the wiper or there is enough capacitive coupling between the shaft and the wiper to give this effect. Trying mounting the pot where it is supposed to go.
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