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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Craig
Sawyers
Sent: Wednesday, March 06, 2019 4:29 PM
To: [email protected]
Subject: Re: [TekScopes] 91% Isopropyl Rubbing Alcohol to clean
potentiometers?

WD40 is a different thing. I think it is mostly a water displacement
compound... and, it is very good at that... for driving water, or
moisture, out of closely fitting parts. It does clean, or dissolve
too. And it will lubricate (at least temporarily... the liquid
lubricant (low viscosity petroleum distillates and very fine mineral
oil?) evaporates fairly quickly, and leaves a white residue (not sure
if the white stuff has lubrication properties.) I have used it to free
really stuck potentiometer shafts, where they pass through the
bushing... the WD40 runs easily into the busing, and some mechanical
force frees up the shaft. I don't like to use penetrating oil. It is
kind of a last ditch thing to try, if other methods fail to unseize
the shaft... and sometimes nothing seems to work too.

There is a subculture of old Teleprinter collectors who have nothing good to
say about WD40. If you use it to lubricate one of those supremely intricate
mechanisms, it dissolves all the old gummy grease and deposits it in the
moving parts. Which totally seizes the mechanism.

The only solution is to totally strip the many hundreds of parts in the
machine, clean every part and reassemble with correct lubricants.

Craig

On 6 Mar 2019, at 22:29, Craig Sawyers <c.sawyers@...> wrote:

WD40 is a different thing. I think it is mostly a water displacement compound... and, it is very
good at
that... for driving water, or moisture, out of closely fitting parts. It does clean, or dissolve
too. And it
will lubricate (at least temporarily... the liquid lubricant (low viscosity petroleum distillates
and very
fine mineral oil?) evaporates fairly quickly, and leaves a white residue (not sure if the white
stuff has
lubrication properties.) I have used it to free really stuck potentiometer shafts, where they pass
through the bushing... the WD40 runs easily into the busing, and some mechanical force frees up the
shaft. I don't like to use penetrating oil. It is kind of a last ditch thing to try, if other
methods fail to
unseize the shaft... and sometimes nothing seems to work too.

There is a subculture of old Teleprinter collectors who have nothing good to say about WD40. If you
use it to lubricate one of those supremely intricate mechanisms, it dissolves all the old gummy grease
and deposits it in the moving parts. Which totally seizes the mechanism.

The only solution is to totally strip the many hundreds of parts in the machine, clean every part and
reassemble with correct lubricants.

Craig

On 06/03/2019 22:03, Roy Thistle wrote:

Hi All:
There are three kinds of pots in common use, that I remember about: these are wire wound, carbon film, and plastic film. Also, there are ceramic film pots now too. I think many of us are familiar with the sound and feel of wire wound pots. The de-greasing, deoxidizing, anti-oxidizing, and lubricating properties of "cleaners" such as they are assumed to be... or claimed to be... seem to make sense to me, for wire wound pots. For carbon film, and plastic film.... and probably ceramic film... I think de-greasing, and lubrication makes sense.
Many of the pots, in the parts lists, of some Tek scopes, are specified as being manufactured by Bournes. If anyone is interested, Bournes publishes a book "The Potentiometer Handbook" in the 1970's... which is 50 years ago... but, I don't think the technology of electro-mechanical pots (like those used in old Tek scopes) has changed that much... except, I don't think they had ceramic film pots... and the build quality was much better? Anyway, pots are interesting... there are linear, log, trig, and multi-turn, as least... and the Bournes book is comprehensive.
Regards.



.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Roy Thistle
Sent: Wednesday, March 06, 2019 3:17 PM
To: [email protected]
Subject: Re: [TekScopes] 91% Isopropyl Rubbing Alcohol to clean potentiometers?

Hi:
I think that high concentration IPA might... but only after prolonged contact (like soaking a part in it, in a closed container) partly dissolve some of the binders, or plasticizers, in rubber or plastic parts (Some of those are to a degree soluble in IPA.) . IPA is, to some extent, going to attack natural shellacs, varnishes, and lacquers (IPA might be similar to the solvents they use.). So caution might be advisable with old electronics, that might have used these in their manufacture.

Most of the chemicals that Bob mentions are de-greasers. As Bob points out acetone (in some nail polish removers) is a strong degreaser (Usually used on bare metal because it can dissolve, or weaken, some plastics, and paints.) Of all the strong degreasers Bob mentions, acetone is available, and is not very toxic (though good ventilation is necessary, and no sparks or flames).

There are also chemicals that are de-oxidizers, anti-oxidants, and lubricants (usually just being one of those kinds of things.) Some "cleaners" claim to be all those things. In other threads there were discussions about the different kinds of Deoxit, for sale. I don't use it. And, I don't know about it. So, I am not saying it works, or it doesn't... I don't know. But, I am listening and researching. The main things that turn me away from "cleaners" is I don't usually know what is in them (So, I don't know what I am using.) That and, the amount of woo around them. They are expensive too. And some of that might be just because people might not know how cheap and available, the chemicals that they use, are (because we don't know what is in them.)

WD40 is a different thing. I think it is mostly a water displacement compound... and, it is very good at that... for driving water, or moisture, out of closely fitting parts. It does clean, or dissolve too. And it will lubricate (at least temporarily... the liquid lubricant (low viscosity petroleum distillates and very fine mineral oil?) evaporates fairly quickly, and leaves a white residue (not sure if the white stuff has lubrication properties.) I have used it to free really stuck potentiometer shafts, where they pass through the bushing... the WD40 runs easily into the busing, and some mechanical force frees up the shaft. I don't like to use penetrating oil. It is kind of a last ditch thing to try, if other methods fail to unseize the shaft... and sometimes nothing seems to work too.

As Bob mentions.... I've had good success with "exercising" a "scratchy" pot too.
Regards

On Wednesday, March 6, 2019, 11:55:07 AM PST, Bob Albert via Groups.Io <bob91343@...> wrote:

For the general information of the group, here is a link to determine characteristics of various solvents, etc.? It provides more information than you will ever want to have.
The Most Complete Free Material Safety Data Sheet (MSDS) list of chemical information on the Internet


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The Most Complete Free Material Safety Data Sheet (MSDS) list of chemica...

Looking for MSDS information regarding the chemicals in a commercial product or a material safety data sheet (MS...
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? ? On Wednesday, March 6, 2019, 11:16:45 AM PST, Roy Thistle <roy.thistle@...> wrote:

Hi:
Lots of companies sell it. I see it on Amazon for 13.00 U.S. a gallon (4, 1 quart plastic bottles.) It is very hydroscopic (absorbs water from the air readily)… so unless you store it over a drying agent, it will tend towards 90%, as it picks up water, from the air that gets into the bottle.
The main advantage of IPA is it is cheap (really cheap compared to proprietary cleaners, like Deoxit). But, another significant advantage is that it is a pure (other than the little bit of water)… it is a pure chemical. So, you know what you are using, and can find out what it will do to what you are using it on (That part needs some research, or advice.). You can get (download) the Material Safety Data Sheet (MSDS), so you can determine how it will affect you, how to use it safely, and how it will affect the environment. The MSDS for many proprietary cleaners don't significantly identify what's in them (it's proprietary).
Regards

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Roger Evans via Groups.Io
Sent: 06 March 2019 20:37
To: [email protected]
Subject: Re: [TekScopes] 7834 with bad HV transformer free to good home

David,

I have a 7934 which is in good health apart from some damage to the storage meshes at the front of the CRT, works fine in non-storage mode. I have been hoping for some time to find a good CRT from a 7834 or 7934 as a replacement. I would be delighted to come and collect. You can contact me at r.g.evans@... to minimise clutter on the list.

Many thanks,

Roger Evans

On Wednesday, March 6, 2019, 11:16:45 AM PST, Roy Thistle <roy.thistle@...> wrote:

Hi:
Lots of companies sell it. I see it on Amazon for 13.00 U.S. a gallon (4, 1 quart plastic bottles.) It is very hydroscopic (absorbs water from the air readily)… so unless you store it over a drying agent, it will tend towards 90%, as it picks up water, from the air that gets into the bottle.
The main advantage of IPA is it is cheap (really cheap compared to proprietary cleaners, like Deoxit). But, another significant advantage is that it is a pure (other than the little bit of water)… it is a pure chemical. So, you know what you are using, and can find out what it will do to what you are using it on (That part needs some research, or advice.). You can get (download) the Material Safety Data Sheet (MSDS), so you can determine how it will affect you, how to use it safely, and how it will affect the environment. The MSDS for many proprietary cleaners don't significantly identify what's in them (it's proprietary).
Regards