Last updated: 28 September 2006

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This page is for user comments and information of a general nature or items applicable to all LXD55 and LXD75 models. If you have any comments, suggestions, questions or answers to questions posed here, e-mail them to me and I'll post them. Please use an appropriate Subject Line on your message. Thanks.

Subject:	motor fault related to extra weight of sbig camera?
Sent:	Wednesday, September 27, 2006 18:21:04
From:	jim cadien (jcadien1@cox.net)
I have had my LXD55 for several years now, carrying a black tube C8,
without more than the small, usual problems.  I recently purchased(used)
a Williams Optic Crayford focuser and an SBIG ST7 ccd camera. When I put
them on the back, I need a little additional weight on the front of the
OTA.  The sum of weights of the three items is about 7 pounds.  I now
need to use two 10 pound counterweights, about halfway on the
counterweight shaft.

When I start the autostar, things seem fine.  The mount slews at high
speed.  However, after a few minutes of tracking I get a motor unit

The system seems well balanced, and the behavior is the same in various
positions, with the OTA on both sides of the mount.  Do you feel that
the additional weight is enough to cause the motor problem?  An
additional test, with the camera, but not the focuser and the addional
weight on the OTA.  Needed only one counterweight.  This seems to
operate ok.


Jim Cadien
Mike here: The weights, both counterweights and accessories, add mass that needs to be moved. So even though the system may be in balance, getting things moving and stopping could be a problem.
Subject:	LX90 groups
Sent:	Monday, September 25, 2006 07:08:31
From:	Moss Colin (Colin.Moss@uk.fujitsu.com)
I've read your excellent site on the LXD55 and wondered if you knew of a
similar site specific to the LX90

Many thanks

Colin Moss
Mike here: There is "Jan's Meade LX90 Pages": m1.aol.com/kewtasheck/lx90.html
Subject:	similuarty between LXD75 & LXD55
Sent:	Friday, September 22, 2006 18:41:37
From:	Harold Ogden (hlogden31@msn.com)
I have an LXD75 with autostar that works fine, I just acquired a LXD55
without a autostar and decided to try it out so I hooked up my autostar
from my LXD75 and tried to use it and the LXD55 was squirley the Dec
axis kept on creeping after I aligned it? I did not change the setup to
indicate that I was using a different head. Are they not the same? 
Mike here: You need to CALIBRATE MOTOR and TRAIN DRIVES when switching the Autostar from one mount to the other one.


Thanks I only have one Autostar so I won' t use it I bought another one
online should be next week, the guy I bought it from was using this one
on an ETX70 I wonder if I should clone it from my other one first and
then do what you said arold
Mike here: Are you getting a #494 AutoStar (which is standard on the ETX-70 and doesn't have number keys) or a #497 AutoStar? The LXD55/75 requires the #497.


I should have told you it's a 497  Harold

Sent:	Thursday, September 21, 2006 22:14:29
From:	LOREN MEECH (lameech@msn.com)
Can you recommend any heavy-duty tripods for this telescope (price not a
consideration)?  I have the equatorial...
Mike here: The LXD75 makes a fine upgrade from the LXD75. How much of a heavy duty mount do you need?
Subject:	Polar Alignment
Sent:	Monday, September 18, 2006 09:52:10
From:	Dave Wallace (d_wallace@ecrm.com)
Ken, remember that the polar alignment scope is going to reverse the
image left-right.  If its field of view were large enough to include
Kocheb, then you'd see that star on the opposite side of the polar cross
from Polaris when Polaris was in the circle.  But you're viewing Kocheb
directly when you align the counterweight rod and Polaris through the
finder when you try to set azimuth.  No wonder it's confusing!

Aloha kakau


From:	Ken Archer (kenarcher@iolc.org)
Actually you are correct! I have an extra Polar finder and just looked
through it without the mount attached and the image is inverted. That
makes sense to me now. I could not figure what was happening to the
pointing. When I carried the LXD-75 head in I felt a clunking turns out
the Dec gears were really loose. Duh! Some of us guys are spoiled with
the fixed observatories and don't get enough star party setup time.
Thanks for the great article it makes sense now and thanks for
straightening me out. J

Subject:	Re: Pictor Autoguiding: DEC trouble
Sent:	Sunday, September 17, 2006 03:53:05
From:	Gernot Stenz (stenzg@in.tum.de)
I would like you to know that I could solve the Problem in the
meanwhile. Cleaning, regreasing and readjusting the worm drive brought a
slight improvement for the DEC movement.

But mostly the success was due to a different preparation of the Pictor
calibration routine. Now I move the mount up before starting the
calibration so the Pictor can directly move the DEC axis without having
to slew across the backlash. Now the pictor successfully guides the LXD,
indicated by two pictures stacked from 2 and 4 minute subs:



Thanks everybody, Gernot

    __o  Gernot Stenz  e-mail:stenzg@informatik.tu-muenchen.de        /\
   -\<,          WWW:  http://www4.in.tum.de/~stenzg               /\/--\
_(_)/(_)_Strasbourg - Paris: 3639 km______________________________/      \

Subject:	Polar Alignment question
Sent:	Sunday, September 10, 2006 18:51:13
From:	Ironwood Observatory (kenarcher@ironwoodobservatory.com)
I've alway's enjoyed reading your site in fact today I found the
information on fixing loose gears on my new LXD-75.  I want to ask this
ask a question. The article polar alignment
http://www.weasner.com/lxd/techtips/polar_alignment.html does not agree
with the article about the article showing the Polar alignment scope.

My email is to only clarify the difference that the cross hair in the
polar scope is NCP?  The Kocab aritcle it will assumes that Kocab is on
the other side of the Polar circle between the end of the counter weight
bar and Polaris. Take a look and maybe some clarification.

Please I don't want to dis anyone, only clarify.
Mike here: The crosshair is the NCP but it is not Polaris, which is about a degree away from the NCP. I think that is what both the article on my LXD site and the one on the other site show.


Yes exactly, but if you have Polaris in the circle and Kochab at the end
of the counter weights then the NCP X hair is on the other side of
Polaris. Not on a line between Kochab and Polaris. That is the point I
am making.


Subject:	LXD 75 diagram
Sent:	Thursday, September 7, 2006 08:12:19
From:	Rickie Rainwater (rickie03@sbcglobal.net)
I need a diagram of the meade LXD 75 mount.  I used your site's tech
tips to fix a gear problem, but for dismantling the rest of the mount
for inspecting and cleaning the worm gears ect, I could use a diagram. 
I guess I could wing it, but I prefer not to guess.
Rickie Rainwater
Mike here: Haven't come across one.
Subject:	Hypertune
Sent:	Monday, September 4, 2006 15:05:56
From:	Steve (bullfox@comcast.net)
I finally did the hypertune, and let me say the results are well worth
the time and effort.  The mount is now very smooth and quite, and tracks
without jerking slipping or backlash.  However, I encountered some
problems getting there!  Most of the problems were with the RA motor. 
The screws holding it to its plastic case were so tight the Allen wrench
stripped the heads.  I finally had to cut slots in them with my motor
tool and got them out with a regular screwdriver.  I replaced them with
some short 4-40's.

The worst problem was with the RA encoder.  After replacing the encoder
wheel with the supplied new encoders which I spray painted flat black, 
I noticed that the encoder wheel hub was so crooked on the shaft that
the encoder was rubbing on its pickup for almost half a revolution.  It
takes a .035 Allen head wrench which is not supplied with the hypertune
kit, so I filed down a .050. Allen wrench to get it off the shaft.  It
turned out that the hub was too large for the shaft and no amount of
adjusting would make it run true.  I finally shimmed it with a little
piece of paper cut from the hypertune instructions, and got it to run
dead on.

I reassembled everything.  When I turned on the mount, the RA motor ran
away at high speed, and I got a motor fault error message.  I took it
back apart and could find nothing wrong.  I was afraid I had screwed up
the electronics.  On a hunch, I looked at the RA pickup under a
magnifying glass.  Black paint had rubbed off the encoder wheel onto the
pick up.  After cleaning off the paint, and reassembling everything I
still had the same problem!    This time I let the motor fault error
message run all the way through.  At the end of the message I hit the
enter key on the handbox as the message instructed.  Both motors
hiccupped once and then every thing ran perfectly!

Apparently, the RA pickup had not been getting a signal due to the paint
so the electronics thought the RA axis was jammed.  When I hit enter, it
thought the jam had been cleared, but still needed to reset itself!

Tonight I am going to take it out to the local dark sky site, realign it
and retrain train the drives  and see how it does.  I will let you

Subject:	Pictor Autoguiding: DEC trouble
Sent:	Monday, September 4, 2006 05:16:30
From:	Gernot Stenz (stenzg@in.tum.de)
I have some problems getting the autoguiding on my LXD-75 to work
properly. At the moment I have run out of ideas and wonder if anybody
here has some knowledge that might help me. I have posted a similar
message to the LXD55 Yahoo group.

A few months ago I obtained a #909 APM, yet due to bad weather I hardly
got to test it.  Last month I had a go at a test run and the results
were mixed.  My setup consisted of an ED80 refractor for an imaging OTA
and a 90/1250 Maksutov as guide scope. Guiding was to be done using my
Pictor 201XT guider.  This weekend I was able to conduct a few more test
runs on this matter. Friday night I took a number of 120 seconds subs of
Hickson 10, last night I simply centered on Scheat (w/o really perfect
polar alignment) and gathered a series of 60s subs. These (for those who
are interested) can be found here:


You can see from these frames that guiding in RA is not a problem (in
both cases 2"/pixel). Dec guiding, however, is a really annoying

First of all, for some reason the guider calibration was a bit
troublesome. I had a live webcam view so I could see the calibration
routine go smoothly in RA, yet I always got errors in Dec. Apparently
the backlash compensation can be a bit of a problem when the LXD takes
too long to reverse the Dec direction. I had to fiddle with the
Dec-Percent (between 70 and 80%, quite unusual) and Calibration
parameters quite a bit until I got the Pictor to calibrate.

The guiding went smoothly at first, RA guiding was flawless and so was
Dec guiding... initially. But after a while, when the first Dec
corrections became necessary, the trouble began. Two minute exposures
showed significant deviations in Dec with RA still perfect.

So here I am with a situation completely orthogonal to my previous
guiding experience: RA guiding easy, Dec guiding troublesome. I really
am puzzled. The Dec worm had just been readjusted (although in much
warmer temperatures than we have now), the balancing of the setup was
not off by too much, I cannot really explain what caused the
not-smooth-at-all Dec movements during calibration. The seeing
deteriorated quite a bit later in the night, but if the guider was to
chase the seeing it should show up in both RA and Dec.

I see the following parameters that can be tweaked:

1) Dec worm play
2) Pictor calibration times
3) Dec gear position before calibration
4) Autostar Dec percent for calibration
5) Autostar Dec percent for guiding

I played around with these values quite a bit, but for the time being I
can only switch between the guiding lagging behind or the guiding
overshooting. For the Friday night run the worm was adjusted rather
tightly, for last night I loosened it a bit. Still in both cases Dec
corrections seemed a bit jumpy when they fist kicked in and smoothed out
only a bit later into the movement (very much unlike the Vixen mount).

Does anybody have an idea how to get the Dec drive to behave?

CS Gernot

    __o  Gernot Stenz  e-mail:stenzg@informatik.tu-muenchen.de        /\
   -\<,          WWW:  http://www4.in.tum.de/~stenzg               /\/--\
_(_)/(_)_Strasbourg - Paris: 3639 km______________________________/      \

Subject:	LXD 76 RA motor 
Sent:	Friday, September 1, 2006 12:14:29
From:	Rickie Rainwater (rickie03@sbcglobal.net)
How do you disassemble the RA motor to check for loose or mis aligned
Rickie Rainwater
Mike here: Remove the inspection port cover on the housing. There is also one on the DEC motor housing.

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