Static sound when turning the Volume knob?

[salduchi]

So I resently got a beautiful new vectrex. Looks brand new like it was barely ever used. One thing I notice though, is when I turn the volume knob, there is some static sound I hear. One I stop turning the knob, the sound sounds perfect. Only static when turning the knob. I know it isent that big of a deal, but does anyone know why it's doing this? Thanks for any replys.

[gauze]

dried up pot, you can try spraying it out with some DeOxit followed by the DeOxit lube stuff whose names escapes me.

[salduchi]

Could it eventually get worse over time? What exactly is a sound pot and how does it work? I don't know much about this stuff.

[gauze]

a potentiometer (pot) is a variable resistor.

how it works is there is a strip of resistive material and a "brush" inside. there are 3 tabs/leads on a pot, let's just call them a,b,c left to right, tabs 'a' and 'c' are connected* via a strip of resistive material, the "brush" is connected to tab 'b' in the middle, as you twist the knob the brush rotates over the surface of the semicircle strip of resistive material effectively making the amount of resistive material between tabs 'a' and 'c' longer or shorter in relation to tab 'b'. when you pass some electricity between tab 'b' and (for example) tab 'a' as you turn the knob the more distance the charge passes through the harder it has to work and the less gets through and the volume is lower. I think the reverse is obvious now.

Hope this helps.

* and if you haven't guessed connecting across tabs 'a' and 'c' gives you a resistance that is not variable, the key is the tab with the brush!

(and yes it could get worse over time but as far as vectrex issues go this is about the most minor!)

[kokovec]

Sometimes if you turn the knob all the way back and forth many times (with the Vectrex turned off) that will be enough to clean up the pot.

[jasonbar]

Common problem with almost all pots. Gunk gets in & hampers the connection between the wiper & the track.

I've attacked this many many times on jittery Atari paddle controllers. Atari used grease lube in the pots to reduce wear, but this also attracted dust & made it stick, which later hampered precision control in Kaboom!

The Atari paddle is easy to take apart, & the pot is easy to take apart & wipe clean.

The Vectrex volume knob requires a good amount of disassembly to access. I'd recommend leaving it as-is.

Thanks,
-Jason

[VectorX]

Aug 7, 2014 10:05:25 GMT -5 kokovec said:

Sometimes if you turn the knob all the way back and forth many times (with the Vectrex turned off) that will be enough to clean up the pot.

Worked for my stereo, so now the volume doesn't alternate in between speakers when I play games on my Genesis and run it through my stereo Thanks!