Last updated: 16 February 2002

Replacing the RA / Azimuth mechanical stop

Sent:	Saturday, February 16, 2002 10:55:29
From: (Clay Sherrod)
Sorry about the hard stop.  The hard stop in the RA is a VERY hard fix
to make; you must remove the entire turntable from the base, and that
means a total disconnect of all wiring going into the DEC arms.  This is
next to impossible to do, because the wiring loom is actually part of
the DEC control panel; there is not place to disconnect, but I have a

** I would NOT recommend this procedure for anyone except someone with
some major electrical experience such as yourself.

1) remove the chrome lock clamp on the azimuth via the tiny set
screw...these strip so be careful

2) carefully remove the base plate being careful to not pull out the
battery wires from the circuit board; here, if you chose and want to
"repair" you can snip the wires and put connectors on them to facilitate
the rest of the repair.

3) once the plate is off and those wires are disconnected, you must NOW
also snip the four (4) wires you see going up into the threaded bolt
that goes through the main drive gear....otherwise you WILL break them
up inside the turntable.  You can also put connectors on here if you
like or mend when you are done.

3) now slowly unscrew the bolt that was beneath the chrome clamp lever
until you can stop and UNTHREAD the RA clutch plate by hand from inside
the do not want to unscrew the bolt so much that the wires
inside it twist and ultimately break.

4) remove the RA gear and clutch  and using large visegrip pliers,
remove the very large RA axis nut you will see completely....

5) once off, you can now pull the entire turntable/fork arm assembly out
of the base.

6) you will clearly see where the RA stops are....what I would suggest
is to NOT attempt to "fix the broken pin" but to carefully insert a new
small self-threading stainless steel screw to serve as a hard stop. 
This will last much longer!

6) reassemble carefully in reverse order and reattach all DEC bundle
wires carefully.

Best of luck!!

Dr. P. Clay Sherrod
Arkansas Sky Observatory

  ----- Original Message ----- 
     Dr. Clay,
     Hello from Bridgeport,Ohio.This is Ron,#202-125.Everything is fine
     here as the last two weekends have been 9-10 viewing.The guided
     tours with the Autostar are such a delight. My daughter, Amy, can't
     believe that she is really looking at Saturn.It is good!

     I might have a problem though. While view terrestial objects with
     the regular hand controller,I think I wiped out the mechanical
     stop. The base free wheels and it doesn't stop to set it in the
     home position.

     I was wondering if you could enlighten me on how to correct this
     problem. I am an electrician by trade so I feel confident opening
     the ETX. Any input would be much appreciated. Thank you

Mike here: As with many of the tips in the Telescope Technical Tips section, doing any of the above will invalidate any warranty and you can end up causing more damage than you started with.

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