Paul Burridge wrote:

Hi,

I bought a big bag of surplus assorted trimmer pots at a radio rally 2
years ago. They're all unused, which I assumed meant they'd be
trouble-free. However, many of them seem to have gone very 'noisy' and
if one tries to wind them from one end to the other, the resulting
voltage readings jump around a lot and often have 'blank' areas for
part of an arc where no contact seems to be being made between wiper
and track. I immediately suspected that they'd probably require a good
dousing with switch-lubricant, but I'm not sure if that's the best
remedy and even if it is, there doesn't seem to be any serviceable
access into them through which one might be able to spray some lube.
The ones I have are between a quarter and one-half inch in diameter
approx and have a protective casing around them, unlike the good old
skeleton presets one could get at easily. Anyone care to give me any
tips on the best way to revitalise these old pots?

Thanks.


A trimmer pot shouldn't be intended for use in a circuit requiring
frequent adjustment - which means that the noisy behavior you
see may not be a show stopper. You can crank the thing through
a few cycles which may clean it well enough for use. If you are
going to toss them anyway, then experiment to see if you can salvage
them. Someone mentioned WD-40. You could dunk one in
isopropyl alchohol and crank it while immersed, then let it air dry.
It's worth experimenting, even if you end up tossing them all.
At least you'll learn what doesn't work!

wrote:

Paul Burridge wrote:

Hi,

I bought a big bag of surplus assorted trimmer pots at a radio rally 2
years ago. They're all unused, which I assumed meant they'd be
trouble-free. However, many of them seem to have gone very 'noisy' and
if one tries to wind them from one end to the other, the resulting
voltage readings jump around a lot and often have 'blank' areas for
part of an arc where no contact seems to be being made between wiper
and track. I immediately suspected that they'd probably require a good
dousing with switch-lubricant, but I'm not sure if that's the best
remedy and even if it is, there doesn't seem to be any serviceable
access into them through which one might be able to spray some lube.
The ones I have are between a quarter and one-half inch in diameter
approx and have a protective casing around them, unlike the good old
skeleton presets one could get at easily. Anyone care to give me any
tips on the best way to revitalise these old pots?

Thanks.

A trimmer pot shouldn't be intended for use in a circuit requiring
frequent adjustment - which means that the noisy behavior you
see may not be a show stopper. You can crank the thing through
a few cycles which may clean it well enough for use. If you are
going to toss them anyway, then experiment to see if you can salvage
them. Someone mentioned WD-40. You could dunk one in
isopropyl alchohol and crank it while immersed, then let it air dry.
It's worth experimenting, even if you end up tossing them all.
At least you'll learn what doesn't work!
In the old days (many years ago) we used "Quietrole", a red liquid,
on pots. It contained carbon tet AND a lubricant (I was told back then)
and it worked very well. Of course that was on the older rotary pots
in use at the time.
I think that stuff may still be available in a spray can, but it
has been quite a few years since I bought a can of it. --Phil

--
Phil Munro Dept of Electrical & Computer Engin
Youngstown State University
Youngstown, Ohio 44555

Phil Munro wrote:
In the old days (many years ago) we used "Quietrole", a red liquid,
on pots. It contained carbon tet AND a lubricant (I was told back then)
and it worked very well. Of course that was on the older rotary pots
in use at the time.

DeOxit makes a 5% spray that's good. However, the OP says he can't see a
way into the trimmer body.

--
If Kerry can't cope with the "Republican Attack Machine",
how can he hope to deal with Al Qaeda?

clifto wrote:

Phil Munro wrote:

In the old days (many years ago) we used "Quietrole", a red liquid,
on pots. It contained carbon tet AND a lubricant (I was told back then)
and it worked very well. Of course that was on the older rotary pots
in use at the time.

DeOxit makes a 5% spray that's good. However, the OP says he can't see a
way into the trimmer body.

With the Quietrole stuff and the old rotary pots, we used to have
some success with taking the knob off and dropping some liquid on the
shaft. It didn't work as well (as fast) as squirting it into the open
spot on the pots, but it would work many times.
But as I remember it, it was important to get something specifically
for cleaning pots, since carbon tet by itself would not leave behind
the appropriate lub for a lasting solution. --Phil
--
Phil Munro Dept of Electrical & Computer Engin
Youngstown State University
Youngstown, Ohio 44555