At 7:53 PM +0000 5/17/02, olympus-digest wrote:
>Date: Thu, 16 May 2002 20:08:02 -0400
>From: "Jim L'Hommedieu" <lamadoo@xxxxxxxx>
>Subject: Re: [OM] Light Meter Problem
>
><Amazed> They used "radiator" flux within a camera? </Amazed>
>
>- ----- Original Message -----
>From: "John Hermanson" <omtech@xxxxxxxxx>
> > Could be a bad meter ground strap or corroded battery wire. Olympus
> > mistakenly used acid soldering flux on the battery wire during some of the
> > production, which practically guaranteed meter problems (eventually. )
I assume that they had a batch of components with hard-to-solder connections.
This can happen if the components have been stored too long. Many years ago, I
had a batch of Nixie tubes (neon numerical display tubes) whose kovar leads
could not be soldered with rosin flux (used in radio solder). The solution was
to dunk the leads in battery acid (sulphuric acid, 20trength) to clean the
oxide off, wash in very hot water to get the acid off, dry with a towel, and
then solder the tubes into the circuit. Worked great, no corrosion. The
drying step was optional, by the way.
To this day, I prepare Keystone battery holders for use by using tinner's flux
to solder the terminal rivet to the connection tab. One applies the tinners
flux using a toothpick, just a little is wicked into the space between rivet
and tab. Then, proceed with soldering iron and radio solder. When done, wash
the battery holder with very hot water. Later, install the battery holder in
the circuit. If this step is omitted, the battery holders develop intermittant
connections as the atmosphere causes corrosion betweem rivet and tab.
Tinners flux is a yellow fluid consisting of hydrochloric acid plus zinc
chloride dissolved in water, and is available in little bottles at hardware
stores and Sears. Tinners flux is used to soft-solder ordinary steel, and will
work on clean stainless steel as well.
The moral in this heresy is that if you are going to use acid flux, use the
real stuff (very little is needed) to tin the part, wash the residue off with
hot water, and then solder the wire in with radio solder. Acid-core solder
isn't that good, and the residue is almost impossible to remove. Even with the
liquid acid flux, don't use it inside an electronic assembly, as the fumes will
get everywhere. Do the tinning elsewhere, clean up as best you can, install
the part, and then attach the wires with radio solder.
Joe Gwinn
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