Contact cleaner for TEK 465B?

[et...@whidbey.com]

I have a Tektronix 465B. I bought it used because it was one of the
scopes recommended by folks who post here and on the electronics basic
group. And I know hardly anything about oscilloscopes. It has worked
very well until two days ago. The volts/div switch has one position
where the display gets all wanky. I thinks that's the proper technical
term. When any other position is chosen on the switch the display
works perfectly. In the one bad position the display shows different
types of wankyness as I wiggle the selector knob slightly back and
forth. So I'm thinking about spraying some Deoxit D5 into the switch.
I'll probably need to remove the scope cover to do this. Is this a bad
idea? Is there a better solution?
Thanks,
Eric

[Jeff Liebermann]

"Cleaning the Volts/Div Attenuator Switch Contacts in Tektronix 4XX
Oscilloscopes"
<http://fullnet.com/~tomg/tekclean.htm>

"Topic: Contact Cleaner and Switch lubricant"
<https://www.eevblog.com/forum/chat/contact-cleaner-and-switch-lubricant/>

"Tek 465 Cleaning"
<https://www.raynetrepair.us/tektronix-465/cleaning.html>
The recommendation of using WD-40 is controversial.


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Fox's Mercantile]

On 10/21/18 7:44 PM, Jeff Liebermann wrote:
> The recommendation of using WD-40 is controversial.

I refuse to use WD-40 for anything on equipment other than
removing adhesive residue.



--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

[Jeff Liebermann]

On Sun, 21 Oct 2018 21:30:37 -0500, Fox's Mercantile <jda...@att.net>
wrote:

>On 10/21/18 7:44 PM, Jeff Liebermann wrote:
>> The recommendation of using WD-40 is controversial.

>I refuse to use WD-40 for anything on equipment other than
>removing adhesive residue.

I use Goof-Off, which is 25% to 50% mineral spirits. My thinking is
anything that stinks that bad must be powerful stuff.

Wired Magazine send some WD-40 to a lab to check its composition.
<https://www.wired.com/2009/04/st-whatsinside-6/>
Mineral oil, decane, nonane, tridecane, tetradecane, dimethyl
naphthalene, and cyclohexane. Mostly mineral oil, which is the
primary ingredient of most commercial solvents, cleaners, and
penetrating oils. The others are made from kerosene, naphtha, or
stoddard solvent, which I consider to be fairly similar:
<https://www.cdc.gov/niosh/ipcsneng/neng1381.html>
For example, Caig Deoxit Gold is 75% "oderless mineral spirits":
<https://system.na3.netsuite.com/core/media/media.nl?id=1567&c=ACCT113328&h=b0ad953fc4fc4d2d52cc&_xt=.pdf>
Bottom line: They're all basically the same stuff with a few
additives.

All contact cleaners include a mild acid to remove the surface oxides
from the contacts. In the distant past, Cramolin Red contained 95%
naphtha and 5% oleic acid for the purpose. Oleic acid is food safe
which makes it the ideal oxide remover. You can also get it cheap on
eBay if you want to mix your own.
<https://www.ebay.com/sch/i.html?_nkw=oleic+acid>

The problem with oleic acid is that it has to be removed after it
strips off the oxides from the contacts or it will eventually corrode
any exposed copper. That caused problems for Caig, so they removed it
from the mix to be replaced with less aggressive oxide strippers.

Incidentally, if you also want an organically lubricated and smelling
oscilloscope, a little olive oil, which is 55% to 83% oleic acid,
might be an interesting substitute.
<https://en.wikipedia.org/wiki/Olive_oil#Constituents>

[gregz]

Some cam switches I think I just used alcohol. I never did, pbut thinking
of lube or cleaner lube, I love CRC 2-26.

Greg

[jurb...@gmail.com]

Yeah, don't use WD-40 on that. If you really MUST have a lube in there use LPS-2. Then of course give it a squirt of solvent.

I don't like ANYTHING about those switches. I understand why they did it but still just don't like them.

Good luck with it.

[Chris Jones]

Have a look in the service manual - it is online, or at least the one
for the 475 is, and that is the same construction style.

I recall reading that because the contacts are gold, they don't tarnish
and just need the dirt cleaned off, and would not benefit from any oily
residue (as left by many contact cleaner sprays). Also, since they are
open to the ventillation air, any oily residue will make dust stick to
it and bring back the problem sooner than with just a cleaning.

I expect that the recommended cleaning solvent is probably some sort of
Freon, but in the absence of that, pure isopropanol is probably ok.

The little contact forks that press against the PCB traces are very
delicate, so don't touch them with hard objects unless you know what you
are doing.

A problem that I had, with similar symptoms, is that the little
attenuators are socketed, and I had dirty sockets on one of mine.
Pulling out that attenuator and reseating it fixed it - the switches
were not the problem that time.

There is a table in the service manual telling you which attenuators are
switched in for which vertical volts/div setting. Using this table and
your observations about the "wankyness" on each range, you could
probably narrow it down to one attenuator, so that you have to mess with
it in the minimum number of places.

[jjh]

Depending on the switch type, I use the following 'contact cleaners' from:
Caig - Deoxit
CRC contact cleaner
Chemtronics contact cleaner, cleaner&lube
LPS products

I will never let WD40 near any of my electronic stuff or mechanical stuff. Come to think of it, I don't let it near anything I work on.

For Tek scopes of that vintage, where lube is used, the original lube has dried out. After cleaning (to remove the dirt & oxidation, as well as the old lube), it is recommended to relube it. Its been a while since I did this and don't remember what I used, but IIRC, the Tek SM cited the product.

There is a tek scope NG. If you post your question on there, I am sure you will get excellent pointers.
Good luck
J

[et...@whidbey.com]

Thanks everyone for the replies regarding the cleaning of the switch
contacts. I knew you all would come through with good info. Thanks
Jeff especially for the links about cleaning these exact switches. I
figured they would just be some sort of rotary switch. But they are
more complex and take special care. Now that I have the info I am
gonna use it to get the switching working correctly. And to avoid the
rush I'll clean all the other switch contacts too. I guess a machine
shop with oil mist in the air is not the best place for the scope to
be stored. Who knew? I'll have to put it in the separate office.
Eric

[Phil Hobbs]

On 10/21/18 11:42 PM, Jeff Liebermann wrote:
> On Sun, 21 Oct 2018 21:30:37 -0500, Fox's Mercantile <jda...@att.net>
> wrote:
>
>> On 10/21/18 7:44 PM, Jeff Liebermann wrote:
>>> The recommendation of using WD-40 is controversial.
>
>> I refuse to use WD-40 for anything on equipment other than
>> removing adhesive residue.
>
> I use Goof-Off, which is 25% to 50% mineral spirits. My thinking is
> anything that stinks that bad must be powerful stuff.

Goof-off has n-methyl 2-pyrrolidone (NMP) in it, and that stuff goes
through your skin super fast. It's not especially dangerous as organic
solvents go, but still it's best to wear gloves.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

[Jeff Liebermann]

On Mon, 22 Oct 2018 16:35:54 -0400, Phil Hobbs
<pcdhSpamM...@electrooptical.net> wrote:

>On 10/21/18 11:42 PM, Jeff Liebermann wrote:
>> On Sun, 21 Oct 2018 21:30:37 -0500, Fox's Mercantile <jda...@att.net>
>> wrote:
>>
>>> On 10/21/18 7:44 PM, Jeff Liebermann wrote:
>>>> The recommendation of using WD-40 is controversial.
>>
>>> I refuse to use WD-40 for anything on equipment other than
>>> removing adhesive residue.
>>
>> I use Goof-Off, which is 25% to 50% mineral spirits. My thinking is
>> anything that stinks that bad must be powerful stuff.

>Goof-off has n-methyl 2-pyrrolidone (NMP) in it, and that stuff goes
>through your skin super fast. It's not especially dangerous as organic
>solvents go, but still it's best to wear gloves.

Sorta, kinda, maybe. Goof-Off is the brand name, which includes a
variety of products:
<https://goofoffproducts.com/products/>
I should have been more specific. I use Goof Off Gunk and Adhesive
Remover:
https://goofoffproducts.com/product/gunk-adhesive-remover-12-oz/
I use it for removing labels, not for cleaning switch contacts.

The MSDS shows no sign of NMP but does contain oleic acid, ethanol,
ethylene glycol (anti-freeze), ether, limonene, and benzyl alcohol.
<https://goofoffproducts.com/wp-content/uploads/2017/08/GunkAdhesiveRemoverMSDS.pdf>
One of these is probably as bad as NMP because when I use it without
gloves, my hand still reek from the stuff and feel oily hours later,
even if I wash my hands several times. I've also ruined at least two
computer keyboards when the solvents removed the white lettering from
the keycaps, even though I thought I had thoroughly washed my hands.

Goof-Off does make one product with NMP. Their Pro Stength Super Glue
Remover contains NMP:
<https://goofoffproducts.com/product/pro-strength-super-glue-remover-4-oz/>
<https://goofoffproducts.com/wp-content/uploads/2017/08/ProStrengthSuperGlueRemoverMSDS.pdf>
There might be other Goof-Off products that use NMP, but I didn't feel
like going through all the MSDS documents.

An EPA report on NMP use, mfg, distribution, processing, disposal,
etc. See Pg 3 through 13 for other products that contain NMP:
<https://www.epa.gov/sites/production/files/2017-02/documents/nmp.pdf>

As you mention, it doesn't appear to be very toxic:
<https://en.wikipedia.org/wiki/N-Methyl-2-pyrrolidone>
<https://www.epa.gov/sites/production/files/2015-04/documents/methyl.pdf>

[~misfit~]

I'll second the 2-26. It's the aerosol can I'd least like to do without for
electronics work.
--
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)

[Jeff Liebermann]

On Tue, 30 Oct 2018 12:47:40 +1300, "~misfit~"
<shaun.at...@gmail.com> wrote:

>Once upon a time on usenet gregz wrote:
>> Some cam switches I think I just used alcohol. I never did, pbut
>> thinking of lube or cleaner lube, I love CRC 2-26.

>I'll second the 2-26. It's the aerosol can I'd least like to do without for
>electronics work.

Ok, let's see what you get for your money with CRC 2-26:
<https://www.crcindustries.com/products/2-26-174-multi-purpose-precision-lubricant-16-fl-oz-02007.html>
<http://docs.crcindustries.com/msds/2007.pdf>

Chemical Name CAS No %
Distillates (petroleum), 64742-47-8 70 - 80
hydrotreated light
Light mineral oil 8042-47-5 10 - 20
n-Butyl stearate 123-95-5 3 - 5
Fatty Acids, C18-unsatd, 61788-89-4 1 - 3
Dimers
Petrolatum 8009-03-8 1 - 3

Nice job of obfuscating the actual contents, but the CAS numbers
should produce something helpful.

Looks like it's mostly light petroleum distillate, which means
kerosene (paraffin) or something similar. Kerosene can be both a
solvent and a lubricant.

Light mineral oil probably means light mineral oil or white paraffin
oil. Yet another lubricant.

n-Butyl stearate is a fatty acid based on zinc. It's food safe and
kinda waxy. My guess is that it acts as a coating over the contacts
to prevent further oxidation.

Fatty Acids, C18-unsatd, dimers. C18 would be oleic or possibly
linoleic acid. I would guess linoleic acid which is a quick drying
oil. It reacts with oxygen in the air to form a protective coating.

Petrolatum is another name for petroleum jelly or something similar.
No clue what it's doing in the mix.

[Phil Allison]

Jeff Liebermann wrote:

> On Tue, 30 Oct 2018 12:47:40 +1300, "~misfit~"
> <shaun.at...@gmail.com> wrote:
>
> >Once upon a time on usenet gregz wrote:
> >> Some cam switches I think I just used alcohol. I never did, pbut
> >> thinking of lube or cleaner lube, I love CRC 2-26.
>
> >I'll second the 2-26. It's the aerosol can I'd least like to do without for
> >electronics work.
>
> Ok, let's see what you get for your money with CRC 2-26:

https://www.crcindustries.com/products/2-26-174-multi-purpose-precision-lubricant-16-fl-oz-02007.html

http://docs.crcindustries.com/msds/2007.pdf

** OMG !!!

CRC 2-26 now comes in a big, plastic hand sprayer - like weed killer.



.... Phil

[gregz]

My first purchase was large can 12 oz. ? home Depot for about $4, then they
just had smaller cans for MORE money.

Greg

[Jeff Liebermann]

On Mon, 29 Oct 2018 19:03:50 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:
(...)
><https://www.crcindustries.com/products/2-26-174-multi-purpose-precision-lubricant-16-fl-oz-02007.html>

>
>Fatty Acids, C18-unsatd, dimers. C18 would be oleic or possibly
>linoleic acid. I would guess linoleic acid which is a quick drying
>oil. It reacts with oxygen in the air to form a protective coating.
>
>Petrolatum is another name for petroleum jelly or something similar.
>No clue what it's doing in the mix.

I have a guess(tm) as to why the petroleum jelly. It evaporates, but
much slower than linoleic acid, which turns to goo as soon as it hits
the air. That might clog the nozzle of the pump type spray bottle.
Mixing with petroleum jelly should slow down the reaction so that it
turns to goo after it's sprayed on the parts that needs lubrication or
rust protection.

[gregz]

Jeff Liebermann <je...@cruzio.com> wrote:
> On Mon, 29 Oct 2018 19:03:50 -0700, Jeff Liebermann <je...@cruzio.com>
> wrote:
> (...)
>> <https://www.crcindustries.com/products/2-26-174-multi-purpose-precision-lubricant-16-fl-oz-02007.html>
>>
>> Fatty Acids, C18-unsatd, dimers. C18 would be oleic or possibly
>> linoleic acid. I would guess linoleic acid which is a quick drying
>> oil. It reacts with oxygen in the air to form a protective coating.
>>
>> Petrolatum is another name for petroleum jelly or something similar.
>> No clue what it's doing in the mix.
>
> I have a guess(tm) as to why the petroleum jelly. It evaporates, but
> much slower than linoleic acid, which turns to goo as soon as it hits
> the air. That might clog the nozzle of the pump type spray bottle.
> Mixing with petroleum jelly should slow down the reaction so that it
> turns to goo after it's sprayed on the parts that needs lubrication or
> rust protection.
>

The spray action is different from many aerosols. You can get a very
controlled slow output that actually seems to bubble out. It covers parts
nicely.

Greg

[mail...@btinternet.com]

Deoxit Gold - swear by the stuff since it helped us to get this going
system again after 20+ years in a field with the doors open!
http://www.bmpg.org.uk/

Mike

On Mon, 22 Oct 2018 10:45:13 -0700 (PDT), jjh <jjh...@gmail.com>
wrote: