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Was: Re: [OM] Film to flange distance in various OM bodies Is: [OT] Adj

Subject: Was: Re: [OM] Film to flange distance in various OM bodies Is: [OT] Adjustments
From: Motor Sport Visions Photography <msvphoto@xxxxxxxxxxx>
Date: Mon, 22 Jan 2001 10:01:25 -0800
In a message dated 1/19/2001 clintonr@xxxxxxxxxxxxxxxx writes:

<< We had to replace the main circuit of an OM-3Ti not too long ago --
got
it in and went to adjust it -- no adjustments!  Turns out, the
functional values are programmed into an eeprom, reminiscent of the
OM-77!  I wonder if that's to make it CE certified? >>

Could it be a running change? Nice of Olympus to inform you two if that
were the case ;-)

I recall the trend in the late 80s in consumer video cameras to replace
all variable resistor potentiometers with "EVRs" or electronic variable
resistors that were only adjustable when stepping through a test
sequence and adjusting the hex value for that step's EVR. The reasons,
in consumer electronics, for this was (of course) cost and reliability.
Once the settings were made, mis-adjustment due to a variable resistor
changing value simply did not happen. It also was *much* easier to
perform a full (video cameras have *a lot* of adjustments)
alignment...point the sucker at the light box, plug the (not cheap) box
in to the PCB, and step through the procedure making adjustments as
required. Once comfortable with a given brand/model one could perform a
full video camera alignment quickly and easily...it took a job that
previously took hours at times and reduced it to ~30 minutes or so. EVRs
are also much less expensive than analog variable resistors.

Now, it seems unlikely that Olympus would have gone this way in evolving
the OM-3Ti and OM-4Ti seeing as how it appears to all us users they are
not evolving their designs...but stranger things have happened. The
added cost benefit for manufacturing complex electronics with EVRs
instead of analog trim pot is in the ability to replace calibration
technicicans on assembly lines with computerized automated text fixtures
which resulted in more predictable output and lower labor costs. Again,
doesn't make much sense in the OM world unless they have been producing
more cameras more recently than we envision.

My consumer electronic tech .02 cents worth anyway...back to you two
esteemed experts now.

Mike Veglia
Motor Sport Visions Photography
http://www.motorsportvisions.com

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