Volume Pot cleaning Spray

I know how a pot is made, thanks. But in servicing many dozens of audio mixer desks and similar gear, I had much experience with pots and their problems. In almost all cases I ever found, 'crackly' noise could be traced to DC current through the pot - not much current - even a few uA is enough to cause problems. Of course there are plenty of other failure modes too, but this one stands out as being very common. I must admit I dont know exactly what causes the 'crackles', and its true that removing the DC will stop it recurring, but I mostly found that I had to replace the pot too. Certainly modern pots are better than the old carbon track ones, but until the OP says what his pot actually is, and even whether this is the problem, then we are all guessing.

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Regards,

Adrian Jansen           adrianjansen at internode dot on dot net
Design Engineer         J & K Micro Systems
Microcomputer solutions for industrial control
Note reply address is invalid, convert address above to machine form.

"Adrian Jansen"

** A very doubtful claim.

** I service audio mixing desks all the time - been doing so since the 70s - noisy pots and faders are a very common problem, as are noisy switches.

However, the noise problem is NOT due to DC leakage current since this is damn near impossible - cos the inputs AND outputs of audio op-amps are at ZERO VOLTS DC !!!!!

** That issue is SO rare I cannot recall a single example in the last 10 years.

Only an antique audio desk using a single DC supply rail instead of dual +/- rails could be involved.

** This is patently 100% FALSE !!

** Complete drivel.

A simple cleaning operation fixes over 99% of all noisy pots, faders and switches.

** How ridiculous is this getting ????

Modern pots and faders still use carbon tracks - at least 99.99 % of them do. High quality faders may use conductive plastic tracks for long life - but even they can still become quite noisy and need cleaning from time to time.

** What is 100% clear is that YOU are BULLSHITTTING like crazy.

Noisy pots are easily fixed by using a bit of spray lubricant, since the problem is normally just a small amount of gunk adhering to the wiper.

Anyone tech who does not know that is a complete FOOL !!

Anyone who routinely replaces noisy pots and faders instead of simply cleaning them is a CROOK.

..... Phil

Ever heard of input bias current ? Not every design places a cap in the way.

Graham

This will have all the ranting anti-WD40 idiots out in droves, but as Phil says a bit of WD40 usually _permanently_ (as in for many years into the future) cures noisy volume controls.

It is the first thing I would try, assuming the spray can enter the pot. If it doesn't work then very little is lost since you will either have to put up with noise or find a replacement pot and do a change-over.

Changing out pots can be a nightmare on some equipment.

I'd rather burn it down instead and claim the insurance. :)

Ross

It's ANOTHER current source or sink.

Graham