[TenTec] Orion encoders

[M. P. Haynes]

Hi Paul,

>From my experience in the medical electronics industry, I would say the
optical encoders are devices that have a moderate failure rate, in other
words over the life of the device (equipment it is used in) the chances
are probably about 25% for it to fail.  These failures do not necessarily
come after a long use, they could fail early on just as easily.  The
symptoms can be no output, output in one direction only or eratic
operation in either direction.  If you put a scope on the two output
lines you will usually see one whose output is slightly low compared to
the other or one whose output never fully goes "low" (logic level) due to
an offset in the output transistor of that channel.  These are devices
that produce a series of pulses on two output lines.  They have a disc
internal to them that has a series of slits that enable light from a
photodiode to be seen by a phototransistor on each of the channels.  The
earliest ones used an incandescent bulb in them to generate a visible
light beam but most today use infrared solid state devices. These pulses
have a 90 degree phase difference as the encoder knob is turned.  The
direction of rotation is determined by which line "leads" the other in
output.  I hope this explaination helps.

73,

Pat Haynes-K4BEH


On Tue, 9 Aug 2005 00:37:33 -0500 "Glassrus" <glassrus at houston.rr.com>
writes:
> 
> 
> > Every component chosen for use will have some failure rate.  First 
> time 
> in my ham career that I have seen an optical encoder actually fail 
> in 
> service.  Hope it is also the last.  73 bob de w9ge
> 
> I hope so too, but I must report that I have an apparent encoder 
> failure. I
> posted the other day that the PBT/BW encoder on my Orion (with less 
> than
> fifty hours on it) would only encode up, not down. I called Ten Tec 
> and
> explained the problem. I was immediately told that it was most 
> likely the
> rotary encoder. I asked if they had seen this problem before, but 
> got an
> evasive answer. As the unit is under warrantee, and as I was told 
> that it is
> a pain in the hind quarters to replace, I shipped the monster back 
> to the
> place of its birth. Hopefully I will see it again before the 
> Autumnal
> Equinox.
> 
> I wonder if we will see more failures of encoders, or if the Rubin 
> Curse has
> once again visited my doorstep, blessing me with the failure of a 
> part that
> should never fail.
> 
> Your encoders may vary,
> Paul Rubin N8NOV
> Houston, TX
> 
> 
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