Date: Fri, 16 Jun 2023 13:59:50 -0700
Reply-To: Roger Whittaker <rogerwhitt1@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Roger Whittaker <rogerwhitt1@GMAIL.COM>
Subject: Re: Contact in, contact out
In-Reply-To: <CDA8DA8E-D11B-4C9C-BDA7-7BA722428AE8@icloud.com>
Content-Type: text/plain; charset="UTF-8"
Dear Contact no Contact
I agree this is a great reminder of the sensibilities of auto electric
diagnostics
love it - bookmarked
On Thu, Jun 15, 2023 at 8:11 PM Alistair Bell <ragnarhairybreeks@icloud.com>
wrote:
> Very nice!
>
> Love this post
>
> Ab
>
> > On Jun 15, 2023, at 8:35 AM, Tom Neal <tneal4242@gmail.com> wrote:
> >
> >
> >>
> >> Richard Koerner <rjkinpb@SBCGLOBAL.NET>
> >> Subject: Microscopic corrosion on electrical contacts
> >
> > About 80% of electrical problems are contact related.
> > The circuit to an electrical device is:
> >
> > Contact in
> > !
> > Device
> > !
> > Contact out
> >
> > I verify contacts first before replacing parts.
> > Even light bulbs. Do they rattle? Can I see the blown filament? If
> not, maybe contact? I don’t even believe apparently dead batteries are bad
> until I’ve proved it with a voltmeter.
> >
> > At HP a guy taught a course “Contact 101”. It was fascinating and went
> into the macro and microscopic world of contacts. Materials theory.
> Actual equations. Pretty cool.
> >
> > Most of our worst class problems at HP were…are you ready for it…contact
> related, usually opens but sometimes shorts.
> > Gold plated finger pore corrosion (need more nickel), micro connector
> contact with high current, squishy connector membranes between VLSI and PC
> board (torquing super important), flex PC finger connectors (good luck,
> don’t work), and throw in IC silver migration that opens up circuits.
> Pile on top very slight salt contamination and a condensing environment
> giving an unwanted contacts between PC traces.
> > So why wasn’t I a mechanical/materials engineer instead of electrical?
> :-).
> >
> > Some key points from Contacts 101:
> > Movable contacts love to be occasionally exercised, which scrubs the
> surface micro corrosion. (Many times an old Vanagon switch works the
> second time.)
> > As we know, non moving contacts do corrode with current going through
> them or even just sitting there. A little dielectric grease, Vaseline, or
> one of my favorites swimming pool silicone grease (seals plumbing, hoses,
> etc. wonderfully, smooths assembly of parts, and reduces wear…magical
> stuff) will give some protection from oxidizing compounds and is a great
> idea.
> > Some contacts just wear out or corrode too much and need replacing. That
> Vanagon horn contact scratches without lubrication and I think only about
> half of mine is still there.
> >
> > Had a nasty intermittent open loop fuel injection for years on a ‘91
> Olds 98. Something to do with the O2 sensor. Replaced them, fiddled with
> the leads, etc. Dealers and mechanics couldn’t find it. Finally it failed
> solidly. The O2 GROUND wire went to a post with the alternator support
> and other big items on it that heated and cooled. Not a pretty place for a
> delicate sensor connector. Design changed in subsequent years, thankfully.
> >
> > The worst problem my van has now is the wires going to the driver door
> are breaking due to 327K miles of flexing. An uncontact problem.
> >
> > So, yep, right on. If long term contact reliability is wanted, get the
> corrosion off and protect the mating surfaces.
> >
> > Happy Vanagon repairing. Tom
>
--
roger whittaker 604.414.6266
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