Thanks to everyone that has responded to this problem. John Piper told me
today ( from Meade's Engineers ) that when the east key is pressed that
this slows the RA motor speed in 1/2 not stopping it so that loading is
maintained on the worm gear. He is sending me a new hand controller N/C (
very nice as the controller is over 1 year old ). I know this is somewhat
OT, But here goes I even changed the alignment of the ST-4 head 90 deg. to
see if the guiding problem was in the relays. I was able to guide in dec.
with very low errors and the RA errors stayed in a ping pong pattern
4,3,-E,-3 ECT. Anyone know how fast the LX200 can receive and execute drive
commands ? Maybe I can get it to guide with slower exposures. Any
suggestions ? The scope tracks well it RA when manually guiding so I don't
have to make that many corrections but I would like to be able to
autoguide. I will check out the articles on electrical concerns.

Thanks
Doug
----------
R. A. wrote: Thursday, March 26, 1998 9:38 PM
>
> I have been somewhat reluctant to get involved with this issue. I am not
an
> expert on the RA drive. (I know quite a bit about the Dec drive)
>
> As far as the keypad signals go, I suggest you look on my web site under
the
> topic Electrical Concerns/LX200 Analysis/LX200 Keypad operation. There
is a
> detailed description of the signals sent by the keypad to the LX200 main
> computer and vice versa.
>
> I will stat my belief about what is hapening to the RA drive. I believe
that
> when East is pressed the RA drive motor stops to allow the universe to
move
> ahead as it tends to move to the west. When the West key is pressed, the
drive
> motor moves more rapidly than the normal motion needed to keep up with
the
> motion of the universe.
>
> I believe what probably happens is that when the East is pressed and the
drive
> motor stops, the worm settles into the worm gear and hold the telescope
> stationary. Then the universe moves to the west and apparently the
telescope
> moves to the east. The keypad sends one string of 0s and 1s to the
computer to
> accomplish this action. (see above reference)
>
> When the east key is released, the drive motor now starts to move inte
worm in
> the normal siderial direction at siderial rate. However, there is some
lash in
> the RA drive mechanism, just as there is in the dec mechanism. They are
all
> but identical. While this lash is being absorbed, the telescope
continues to
> not move for up to several seconds. Thus the star field continues to
drift
> with respect to the telescope until the lash is taken up.
>
> There is no provision for lash adjustment in the RA drive. If the RA
drive is
> not perfectly adjusted, there will be lash and possibly even retromotion
for
> the same reasons that these defects exist in the dec drive.
>
> A description of the dec drive will give insight into the RA drive as
well. Se
> such under the topic Mechanical Concerns/LX200 Mechanical Concerns/Repair
of
> the dec drive.
>
> I hope these comments will help explain the possible problems with the RA
> drive.
>
> Doc G <http://www.mailbag.com/users/ragreiner>
>

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