Cleaning old volume pots?

[~misfit~]

Hi guys,

I use an (early 80s?) Sansui A-M7 'midi - sized' integrated amplifier and a
couple of Wharfedale bookshelf speakers at my desk to plug into my laptop if
I want to listen to music on-line or just more volume than the internal
speakers can give on youtube etc.

However at lower volumes the channels drop in and out as I turn the dual
ganged volume pot. I've read on line that to fix this sort of thing you just
spray "De-oxit" into the pot and turn it back and forth a few times. However
I've not been able to source De-oxit here in NZ. I use some expensive
aerosol stuff from CRC called "CO Cleaner" for cleaning computer memory
slots etc and wondered if people here think that it might do the job - or
would I be better off trying harder to source this De-oxit?

Cheers and TIA,
--
Shaun.

"Humans will have advanced a long, long way when religious belief has a cozy
little classification in the DSM*."
David Melville (in r.a.s.f1)
(*Diagnostic and Statistical Manual of Mental Disorders)

[Phil Allison]

~misfit~ wrote:
>
>
> I use an (early 80s?) Sansui A-M7 'midi - sized' integrated amplifier and a
> couple of Wharfedale bookshelf speakers at my desk to plug into my laptop if
> I want to listen to music on-line or just more volume than the internal
> speakers can give on youtube etc.
>
> However at lower volumes the channels drop in and out as I turn the dual
> ganged volume pot. I've read on line that to fix this sort of thing you just
> spray "De-oxit" into the pot and turn it back and forth a few times. However
> I've not been able to source De-oxit here in NZ. I use some expensive
> aerosol stuff from CRC called "CO Cleaner" for cleaning computer memory
> slots etc and wondered if people here think that it might do the job - or
> would I be better off trying harder to source this De-oxit?
>
>

** CO will probably do nothing for your noisy pot.

You need a good grease solvent that is slow evaporating and able to penetrate small spaces plus leaves a thin layer of light mineral oil behind.

CRC 2-26 is one such as is the ubiquitous WD40.

Results are almost instant an there is no need to remove the product afterwards as there can be with Deoxit.

Both are also good cleaners for switches and connectors.

Use only as much as needed to get a result - ie not much.


.... Phil

[RMD]

+1 WD40. One little squirt usually effects a permanent (or at least
for many, many years) cure.

Ross

[~misfit~]

Thanks Phil, I'll get some tomorrow hopefully. I only have 808 silicone oil
spray and CRC 5-56 which I use for general automotive stuff and as a
de-facto cutting oil when drilling and tapping metal. It seems that some
2-26 will be a good addition to the cupboard. Come to think of it I have
another Sansui amp in storage with 'slider' linear pots that are noisy
too...

Cheers,

[~misfit~]

Thanks Ross.

[Phil Allison]

~misfit~ wrote:

>
> >
> > ** CO will probably do nothing for your noisy pot.
> >
> > You need a good grease solvent that is slow evaporating and able to
> > penetrate small spaces plus leaves a thin layer of light mineral oil
> > behind.
> >
> > CRC 2-26 is one such as is the ubiquitous WD40.
> >
> > Results are almost instant an there is no need to remove the product
> > afterwards as there can be with Deoxit.
> >
> > Both are also good cleaners for switches and connectors.
> >
> > Use only as much as needed to get a result - ie not much.
>
>
> Thanks Phil, I'll get some tomorrow hopefully. I only have 808 silicone oil
> spray and CRC 5-56 which I use for general automotive stuff and as a
> de-facto cutting oil when drilling and tapping metal. It seems that some
> 2-26 will be a good addition to the cupboard. Come to think of it I have
> another Sansui amp in storage with 'slider' linear pots that are noisy
> too...
>

** Sliders are not the same as rotary pots - be very careful how much WD40 is used or you may remove all the grease that makes the traveller move so smoothly.

The very best way to deal with sliders is to remove and disassemble them - clean completely with WD40 and wipe dry with a tissue or rag. Then regrease the traveller to frame surfaces and reassemble.

I have use a white coloured "marine grease" made by Valvoline with success.

Comes up working like new, long as the track and contact fingers are not too worn.


... Phil

[Ian Field]

"~misfit~" <shaun.at...@gmail.com> wrote in message
news:nc3fc7$jc1$1...@dont-email.me...

Instead of WD40, I use GT85 - same thing except its PTFE enhanced, so far
there's been no problems with PTFE particles lifting wipers.

The more recent the equipment; the more likely to be ABS plastics in various
assemblies - that stuff disintegrates if you spray it with hydrocarbon
solvent.

The old method was rub the track with pencil graphite, but it contains clay
which is abrasive. The heavier the black, the less clay, YMMV.

[~misfit~]

Good info - thanks.

> The old method was rub the track with pencil graphite, but it
> contains clay which is abrasive. The heavier the black, the less
> clay, YMMV.

Yes I've found instructions on doing that during my searches for 'noisy
volume control repairs' - they say use a 4B pencil. Mind you just as many
people say not to do that with equipment manufactured after WWII.

Cheers,

[~misfit~]

Once upon a time on usenet Phil Allison wrote:

Thanks for that Phil. The unit with the sliders is only occasionally used
and I'm not sure I'll bother trying to fix it unless it gets much worse. It
only crackles a bit at low volumes currently.

I'll head out to try to get some CRC 2-26 in a while. It seems it's not a
commonly stocked item even with stores who have a CRC stand or section of
shelving so I may have to order it. Bunnings have it on their site for
$24.99 for a 300ml can but say not available in all stores and the local
Bunnings is very small and usually orders most 'slow movers' in from a
bigger store.

[pedro]

On Sun, 13 Mar 2016 23:31:28 +1300, "~misfit~"
<shaun.at...@gmail.com> wrote:

>Once upon a time on usenet RMD wrote:
>> On Sun, 13 Mar 2016 12:13:36 +1300, "~misfit~"
>> <shaun.at...@gmail.com> wrote:

>>> However at lower volumes the channels drop in and out as I turn the
>>> dual ganged volume pot. I've read on line that to fix this sort of
>>> thing you just spray "De-oxit" into the pot and turn it back and
>>> forth a few times.

>> +1 WD40. One little squirt usually effects a permanent (or at least
>> for many, many years) cure.

I would avoid WD40 or any other product which leaves any oily residue.
Great for nuts and bolts, but on electrical contact surfaces it
becomes a dust-and-crud magnet.

[Fred Smith]

On 2016-03-14, pedro <m...@privacy.net> wrote:

>
> I would avoid WD40 or any other product which leaves any oily residue.
> Great for nuts and bolts, but on electrical contact surfaces it
> becomes a dust-and-crud magnet.

I know that's the theory, but I've been spraying RP7/WD40 in pots
for forty odd years to shut them up and never had a problem. The
device has invariably died before pot noise became a nuisance
again.

[Phil Allison]

pedro wrote:
>
>
> >> +1 WD40. One little squirt usually effects a permanent (or at least
> >> for many, many years) cure.
>
> I would avoid WD40 or any other product which leaves any oily residue.
> Great for nuts and bolts, but on electrical contact surfaces it
> becomes a dust-and-crud magnet.
>

** Superficially, this sounds like a genuine concern - which experience shows is of no consequence in practice. Consider the following facts:

1. The insides of pots, switches relays etc which are themselves hidden inside equipment are not subject to dust. Slider pots may be, but most have curtains protecting them.

2. Metal surfaces coated in an oily film are protected against corrosion due to exposure to moisture or damp air. A coating of light oil has been proved to improve electrical contact by reducing resistance build up as surfaces wear.

3. Pots and most switches have a wiping action between contacting surfaces that displaces light oil. Same goes for connectors.

4. Applying a little WD40 or similar to non-functioning pots, switches and connectors makes them work again in seconds and keep on working.

5. Applying any of the fast evaporating, oil free cleaning products to the same tasks has no permanent effect.



... Phil

[Clocky]

Yeah, and that is why you don't use WD40 and similar products on locks
as it gunks them up and makes the problem worse in the long run.
Locks have keys inserted repeatedly and dust and muck can be introduced
that way. That's not really the case with pots.

The concerns are valid to some degree but I've done it many times and it
works well.

[~misfit~]

Well my can of CRC 2-26 has fiunally arrived. However the amp's no longer
got available bench space as other projects are underway so I'll try it
later [TM].

Oh, I found some Akai ASE-30 two-way headphones for $5 at the Salvation Army
thrift store the other day and the pots on those are scratchy too. They also
'break down' when playing 'busy' music (but sound good with jazz etc.) so
maybe replacing the ~40 year old 22 uF NPE capacitors inside them will fix
that? Here's hoping because I just happen to have some sitting around that
were for a speaker crossover re-build that hasn't happened (yet!).