[mca]

I just bought a used Dehavilland Mercury III preamplifier that has the optional "output level balance controls" on the back. I am noticing that these controls are introducing a "scratchy/fuzzy" noise into the system. What is the best thing to use to try and clean them with?

[mca]

 

[Bemopti123]

I think the usual with controller pots, especially if they have not been used in a while is build up or mild corrosion someone calls it.  I would simply"use", turn the knob left and right as many time as possible.  Make sure that the amp is off.  After doing this several times, that sound should go away.  Some people strap stuff into it but I am a little leery, especially if you do not know where and how.   

[Bemopti123]

Any of the videos might apply to your situation.  https://www.youtube.com/results?search_query=Spraying+stratchy+knob+stereo

[SoCalWJS]

I just bought a used Dehavilland Mercury III preamplifier that has the optional "output level balance controls" on the back. I am noticing that these controls are introducing a "scratchy/fuzzy" noise into the system. What is the best thing to use to try and clean them with?

All the time, or just when you adjust them?

If when turning the knobs, I used to use Tuner Shower. Not even sure it's around any more (Google search returned a Sony Radio for the term). Basically alcohol under pressure - used to clean the contacts.

[mca]

I would simply"use", turn the knob left and right as many time as possible.

I will give that a try.

[mca]

All the time, or just when you adjust them?

All the time.

[Bemopti123]

I think this happens because the trim pot is one of the pots that is hardly used...it is on the back of the unit right?  So, that is why there must be a build up of rust.

[BoJonJovi]

Clean them out with Ronsonol lighter fluid or electronic spray cleaner by flooding them. Probably will not have to take them apart.

[Davey]

Some potentiometers are hermetically sealed and you can't easily get cleaner into them.  But, if there is a little opening somewhere a good douching with spray contact cleaner should do the job.......for a while.  They will eventually get scratchy again though.

Dave.

[richidoo]

Cleaning pots is maintenance task. Using them just moves the dirt around for temporary cure, but noise comes back soon.

Look for some kind of opening into the body of the pot and fill that up with cleaner while turning the knob quickly back and forth. So you're scrubbing the insides while flushing it out. Let it drip out and dry for a few minutes.

If there are no holes on the back of the pot, then you can remove the control knob from the shaft and trickle the cleaner down the shaft into the pot from the front, or use a tool like this to force it in: http://www.stewmac.com/Luthier_Tools/Tools_by_Job/Tools_for_Maintenance/Pot_Cleaning_Cap.htm

I use CRC Electronics cleaner, but Caig D5 is good too. Don't use Caig Gold on pots as it leaves too much residue.