[sf-lug] SF-LUG meeting notes for Sunday December 3, 2017
jim
jim at well.com
Thu Dec 7 14:05:45 PST 2017
great page. I book-marked it. Thanks.
On 12/07/2017 09:03 PM, maestro wrote:
> jim,
> if they happen to be copper there's this:
>
> <https://www.doityourself.com/stry/how-to-clean-copper-contacts>
>
>
> which you most likely know with all your experience(s)...
>
>
> also have you tried 'upping' your alc. level(s) with isopro. or everclear?
> just curious as to whether you found much more benefit to vodka...
>
>
> message ends.
> __________________
>
>
> On Thu, Dec 7, 2017 at 12:45 PM, jim <jim at well.com
> <mailto:jim at well.com>> wrote:
>
>
> yeah, but now the challenge for me is
> to see if/how to apply some AC voltage to
> the secondary and see what appears on the
> primary. I'll use my Variac to adjust the
> applied voltage.
> There's an olde tyme trick of using
> identical transformers, tying the two
> secondaries together, then applying VAC
> to the primary of one and getting more or
> less the same voltage at the primary of
> the other, a DIY isolation transformer.
>
> More practically, given contacts that
> are accessible, what are good solvents to
> clean them? Acetone? Ethyl alcohol (I use
> vodka)? other?
>
>
>
>
>
> On 12/07/2017 04:40 PM, Michael Paoli wrote:
>
> From: jim <jim at well.com <mailto:jim at well.com>>
> Subject: Re: [sf-lug] SF-LUG meeting notes for Sunday
> December 3, 2017
> Date: Thu, 7 Dec 2017 03:43:13 +0000
>
>
>
> 600VDC? with a 10MOhm resistor. Great
> tip!
>
>
> And really only a "great tip" if one knows what the heck one is
> doing, and also only quite applicable to the repair of a
> sealed magnetic reed relay switch - where one does not and
> cannot have physical access to the electrical closure contacts
> of the switch itself. If one can actually reasonably get
> access to the physical electronic switch closure contact
> points (or similar for relay), then there are generally other
> highly preferable methods for dealing with non-conductivity at
> physical closure on contacts due to oxides or pitting or the
> like.
>
> Random: that sealed magnetic reed switch keyboard - probably only
> keyboard I have that *may* be safe to use in an explosive gas
> environment. *May*? Well, that would also depend upon additional
> factors such as other materials used (e.g. sufficiently
> anti-static /
> static resistant materials, etc.). With magnetic reed relay
> switch,
> the actual switch closure contacts are inside a sealed glass
> envelope,
> so no environmental exposure on those, thus the slightest of
> potential
> spark there is isolated from surrounding environment ... no
> KABOOM! from
> switch contacts opening/closing in explosive gas environment.
> And remember, smell gas? Don't switch anything on or off -
> and that includes
> most flashlights, etc., and certainly don't strike a match or
> lighter or
> the like. And also take precautions to avoid static discharge.
> Most all switches aren't sealed like magnetic reed relay switches.
>
> https://en.wikipedia.org/wiki/Reed_switch
> <https://en.wikipedia.org/wiki/Reed_switch>
>
> Another type likewise sealed:
> https://en.wikipedia.org/wiki/Mercury_switch
> <https://en.wikipedia.org/wiki/Mercury_switch>
> But those are much less common these days - notably due to their
> containing mercury (toxic). Also, just because you have an older
> "silent" type switch, doesn't mean it's a mercury switch or
> the like - some "silent" type switches just use a much quieter
> switch closure mechanism, and no environmental isolation of the
> switch contact points. But *some* older "silent" type switches
> may in fact be mercury switches. Sometimes they're also used
> for their gravitational dependency/orientation - e.g. as an
> anti-tip switch to shut off an electric heater if it's knocked
> over. But probably relatively useless for, e.g. keyboard,
> but magnetic reed relay switches work fine there ... though
> not a particularly economical way to manufacture a keyboard
> certainly at least by today's standards and technologies.
>
> On 12/07/2017 03:23 AM, Michael Paoli wrote:
>
>
> oh, and I did have one key on a Cromemco 3102 terminal
> which I'd received
> which didn't work (magnetic reed relay switch ... and
> ... how'd I repair it?
> switch physically closed contacts, but not
> electrically - sealed in a glass
> envelope - apply a rather high voltage (about 600+
> VAC) very limited current
> (about a 10+M Ohm resister in series) ... burnt off
> whatever (oxide?) was
> preventing electrical contact, without welding the
> contacts together - has
> worked fine ever since) ... and after that on the
> Zareason,
>
>
>
> _______________________________________________
> sf-lug mailing list
> sf-lug at linuxmafia.com <mailto:sf-lug at linuxmafia.com>
> http://linuxmafia.com/mailman/listinfo/sf-lug
> <http://linuxmafia.com/mailman/listinfo/sf-lug>
> Information about SF-LUG is at http://www.sf-lug.org/<br>
> Related Information <br>
> http://www.shallowsky.com/blog/
> <http://www.shallowsky.com/blog/><br>
> http://explainshell.com/ <br>
>
>
>
> _______________________________________________
> sf-lug mailing list
> sf-lug at linuxmafia.com <mailto:sf-lug at linuxmafia.com>
> http://linuxmafia.com/mailman/listinfo/sf-lug
> <http://linuxmafia.com/mailman/listinfo/sf-lug>
> Information about SF-LUG is at http://www.sf-lug.org/<br>
> Related Information <br>
> http://www.shallowsky.com/blog/ <http://www.shallowsky.com/blog/><br>
> http://explainshell.com/ <br>
>
>
>
>
> --
>
> *~the quieter you become, the more you are able to hear...*
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://linuxmafia.com/pipermail/sf-lug/attachments/20171207/f571c649/attachment.html>
More information about the sf-lug
mailing list