Volume Pot cleaning Spray - Page 2

Do you have a question? Post it now! No Registration Necessary

Translate This Thread From English to

Threaded View
Re: Volume Pot cleaning Spray

"Ross Herbert"
 Adrian Jansen
Quoted text here. Click to load it


** It's a very deep mystery to  sooooo  many out there .....


Quoted text here. Click to load it


**  The wiper mechanism would easily move tiny carbon particles out of the
way ( ie like a road grader)   -   if it were not for the fact that nearly
all pots and faders (ie slider pots) are packed with grease to improve the
mechanical " feel " when operated.

This grease has the bloody horrible habit of migrating onto the surface of
the resistive track AND  moving metal parts over time  -  so mingling with
and compacting the carbon dust into a thin layer of  *non conductive*  gunk.

It is this **gunk**  layer  that must be removed to restore good operation
to a "noisy" pot.

Products like WD40 do it so damn fast and well,  it makes your head spin.


Quoted text here. Click to load it


**  True,  not only because leaky electros are nowadays a rarity  -  but
that it is very rare now to see coupling electros subjected to any
significant DC voltage at all.

Dual  +/-  supplies have long been the norm in all ( non valve) audio gear
so there is simply no DC voltage to block.




....    Phil



Re: Volume Pot cleaning Spray

Quoted text here. Click to load it

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.

--
Regards,

Adrian Jansen           adrianjansen at internode dot on dot net
We've slightly trimmed the long signature. Click to see the full one.
Re: Volume Pot cleaning Spray

"Adrian Jansen"

Quoted text here. Click to load it

**  A very doubtful claim.


Quoted text here. Click to load it


** 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  !!!!!


Quoted text here. Click to load it

** 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.


Quoted text here. Click to load it


**  This is patently  100%  FALSE  !!


Quoted text here. Click to load it


** Complete drivel.

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


Quoted text here. Click to load it


** 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.


Quoted text here. Click to load it


**  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






Re: Volume Pot cleaning Spray



Quoted text here. Click to load it

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

Graham


Re: Volume Pot cleaning Spray



Quoted text here. Click to load it

It's ANOTHER current source or sink.

Graham


Re: Volume Pot cleaning Spray
On Wed, 1 Apr 2009 22:28:41 +1100, "Joe G \(Home\)"

Quoted text here. Click to load it

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


Site Timeline