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Old 08-07-2018, 11:07 PM
gary
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Join Date: Apr 2005
Location: Mt. Kuring-Gai
Posts: 5,914
Argo Navis Daytime Encoder Test

Quote:
Originally Posted by troypiggo View Post
I don’t often do visual and my Argo Navis has been in storage pretty much since I bought it. Will be pulling the dob out soon and wanted to test the AN/encoders etc still working. Is there a way to test in daylight without having to actually align?
Hi Troy,

You might like to perform what we refer to as the Daytime Encoder Test.

Here is the test as copied directly from the User Manual pp 123-124 :-

Quote:
Originally Posted by Argo Navis User's Manual Daytime Encoder Test
During the day, using a high-powered
eyepiece or cross-hair reticle, center a
distant fixed terrestrial object.
Power on Argo Navis and after it
has initialized, spin the DIAL until the
display reads –

MODE ENCODER

then press ENTER. Now spin the DIAL
until the display reads –

AZ/ALT ENC STEPS
+0000 *0000

When in this mode, the value of Azimuth
steps range from 0 to the number of steps
set in SETUP AZ STEPS minus 1. Altitude
steps range from 0 to the number of steps
set in SETUP ALT STEPS minus 1.
If your mount is of the style that allows
you to lock the Alt (or Dec) axis, lock it.
Take note of the left-hand displayed
value, which is the Az (or RA) encoder
count.

Rotate the mount through 360° in Az
(RA) and re-center the object. Take note
of the displayed Az encoder count value.
Ideally, it should be within an encoder
step or two of the value from which you
started. Keep in mind that the displayed
count “wraps”, so that, for example, a
value that is equivalent to the number of
steps set in SETUP AZ STEPS minus 1 is
only 1 step away from a count of zero.
Now exercise the scope back-and-forth
in Az (RA) to attempt to induce any
potential encoder shaft slippage error, or
the like. Again, re-center the object and
check that the displayed value has
returned to within a step or two of what it
originally was.

Now take note of the right-hand
displayed value, which is the Alt (or Dec)
encoder count.

If your mount is of the style that allows
you to lock the Az (or RA) axis, lock it.
Now exercise the scope up-and-down
in Alt (Dec) to attempt to induce any
potential encoder shaft slippage error, or
the like. Again, re-center the object and
check that the displayed value has
returned to within a step or two of what it
originally was.

To diagnose for hysteresis effects,
carefully observe the display in MODE
ENCODER whilst moving the scope to-and
fro. When you begin to move the scope,
look for any noticeable delay or “lag” from
the time the scope starts to move to the
time MODE ENCODER registers motion.
Start by rotating the mount in one
direction, then stopping and reversing the
direction of travel. If you notice the above
mentioned lag effect from when the scope
begins to move, this is a telltale sign of
hysteresis. It is best rectified by inspecting
your encoder mounting hardware for any
‘play’ and then applying a mechanical fix.
Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au
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