Date   

Re: AP GTO troubleshooting notes

Roland Christen
 

In a message dated 3/13/2001 4:53:23 AM Pacific Standard Time,
tedi@... writes:



Symptom 1 - hand controller 'dies'. Everything is going fine, then
there's some relay clicking noises coming from the mount followed by
no buttons doing anything.

The problem is not a relay in the mount. The clicking comes from the speaker
in the keypad. It can happen one of two ways, either there is a momentary
power interruption from the power supply, in which case the keypad logic
resets, or there is an internal loose connection or other problem inside the
keypad. We are continuing to work with the keypad manufacturer on this, but
so far they have not been able to pinpoint the cause of the problem. The
power connector is a possibility, but we have not found it to be the source
in the majority of the cases. When the power interruption occurs and there is
a clicking noise, the keypad is the only thing that resets, the servodrive
continues to function. In our new keypad software, the keypad will
automatically recover from any power interruption in the keypad. The servo
itself can ride through short spikes on the line because it has built in
capacitors. We have asked the keypad manufacturer to add capacitors to their
circuit, and they are studying the feasibility. The software solution will
make the system much more stable and rugged and eliminate the occasional
resets.

Roland Christen


Re: Chip for 1200-GoTo

Roland Christen
 

In a message dated 3/12/2001 6:32:15 PM Pacific Standard Time,
eroelmx@... writes:


you press #9 key in the Menu or
the menu key to recalibrate to the new position due to the centering
of the object, but if you keep the #9 key pressed, then the object
starts moving in a jerky motion as you say, getting out of the center
position. My question was if that is normal and if I just have to hit
#9 key once, or there is something wrong in my procedure
You only press the #9 key once, quickly. This sends a message to the servo to
update the position of the object. Keeping the button depressed will continue
to send updates at a rate of 3 or 4 per second. Each time you send an
update, the servo microprocessor has to interrupt the normal driving routines
and do an extensive calculation for the update co-ordinates. It is no wonder
then that the drive will look somewhat jerky. Please push the button once,
quickly and be done with it. This Recal really does not need to be done all
the time anyway.

Roland Christen


Re: Chip for 1200-GoTo

eroelmx@...
 

--- In ap-gto@y..., chris1011@a... wrote:
In a message dated 3/12/2001 12:44:05 PM Pacific Standard Time,
eroelmx@y... writes:


I do not know if it is normal that when recalibrating and keeping
the
button on, the mount moves very slowly and in step like manner in
RA,
so please let me know.
I don't know what you mean by keeping the button on. Are you
depressing the E
or W button in 1x? in .5x? or in .25x? or 12x? or what? In any
case, pressing
the E-W buttons should cause the star to move smoothly east or west
at the
guiding rates. If you do not depress the button, does the mount
track the
star at all? Or is there a jerky back and forth motion?

Roland Christen
Roland:
Sometimes the lenguage barrier betrays me and have trouble trying to
explain what I want. Well what I meant is that when you goto an
object and it is not in the center of the field, then after centering
it with the hand pad (E-W-N-S keys), you press #9 key in the Menu or
the menu key to recalibrate to the new position due to the centering
of the object, but if you keep the #9 key pressed, then the object
starts moving in a jerky motion as you say, getting out of the center
position. My question was if that is normal and if I just have to hit
#9 key once, or there is something wrong in my procedure.
This weekend I will go to the observatory to check the RA gear play,
my polar alignment and if there is something else that I could check
please let me know, the observatory is about 80 miles from home, so
it is a 2 hour drive, that is why I would appreciate if there is
something more mechanical or electronic to check while being there.
Receive my best regards,
Eric.




Re: Chip for 1200-GoTo

eroelmx@...
 

--- In ap-gto@y..., chris1011@a... wrote:
In a message dated 3/10/01 7:13:33 PM Central Standard Time,
eroelmx@y... writes:

<<
> > I am having trouble with the tracking, PEC and goto.
> > Thanks, >>

Ok, after reading your other two emails, I believe you have trouble
with the
tracking, pec and goto. But you give me no information to make an
accurate
diagnosis of your problems. Obviously, if all our mounts had this
trouble, we
would not sell any. On one hand, I can probably explain everything
you see on
improper setup, without blaming the mount at all, which would maybe
not be
correct. I am not there, so I cannot check things out for you. You
will have
to be my eyes and ears, and tell me what you see based on waht I
tell you in
this Email and following ones.

1. It is easy and tempting to explain all faults by saying
something is wrong
with the chip. That may or may not be the case. As an example, in
an
automobile, there is a chip that controls a lot of functions. Let's
say the
car runs rough and also won't go straight down the road, instead
keeps
heading for the ditch. A good mechanic would check out the spark
plugs and
wires, and also the wheel alignment, tire pressure, and perhaps ask
if the
driver really had his hands on the wheel while driving. So, for
now, lets
forget about changing the chip, and try to weed out the herrings
from the
mackerel.

2. The mount won't rack the Moon. Well, I would expect that. The
Moon does
not have one tracking rate, neither does it track parallel to the
earth. I
have done a lot of lunar photography, and can tell you that you
cannot track
the Moon accurately with any kind of mount without changing the
altitude and
azimuth alignment. The Moon is a special case, that is not
adequately covered
in any book that I know of. It would seem that one could dial in a
lunar
rate, and the Moon would stay still in the eyepiece. At low power,
yes. At
high power, not at all. The Moon's distance from the earth varies
from day to
day, so the rate at which it moves from east to west varies also.
There is no
one lunar rate. The Moon also moves up and down in its orbit,
sometimes beign
high in the sky, other times being very low. The Moon's orbit is
not parallel
to the earth, so simple polar alignment will not follow the Moon's
motion.
There will always be declination drift, as the Moon moves between
its
northern and southern nodes. If you want the Moon to stay still at
high
powers, you will have to radically change both the elevation of
your polar
axis, and the azimuth angle. Otherwise, it will slowly drift away
in your CCD
camera field. I do this whenever I want to precision high
resolution
photography of the Lunar surface. One would think that the dec
drift could be
counteracted by following it with the dec motor. This is difficult
to do
smoothly because there is a limit to how slowly a servo motor can
be run
before it becomes almost stepper like in its action. The drift in
Dec and RA
is many times slower than the sidereal rate ( varying between 3 to
20 times
slower), that no single motor circuit can be built to smoothly and
accurately
follow this motion, and also slew at 1200 times sidereal. The mount
would
have to have 2 sets of motors, one for slewing, and one for very
slow
motions. This means 4 gears etc.

So, at this point, I say that the Moon is a special case, a red
herring, so
to speak, that is not the fault of the mount, no matter how much
you like it
to be.

3. Slow RA drift. In 99% of the cases where a mount will not follow
the stars
for a period of time, the person did not polar align it properly.
Do you
understand that this can be the case? In fact, one way TO polar
align a mount
is to monitor the RA drift over time, and correct the altitude
angle of the
polar axis. Did you do this to the 1200 mount? The mount cannot do
this by
itself, it is somethign the user must do. Please do not rely on the
Polar
routine in the keypad, it is only approximate. At the powers you
are using
your telescope, you must drift align. Did you drift align the Polar
axis?

4. Slow Dec drift. Same thing applies here. A slow dec drift is
always caused
by the azimuth axis being aimed wrong. The dec axis will
not "drift" due to
faulty motors or chips, the motors are not turning in the dec axis,
unless
you want to go somewhere else.

5. The GOTO does not accurately place the object in the field of
view. If the
mount is not polar aligned, I would expect exactly that. Also, what
affects
GOTO accuracy on a German mount is the degree to which your
telescope is
orthogonal to the polar axis.

6. The PEC will not "fix" the star drift. If the mount is not
properly polar
aligned, I would expect that too. PEC is not intended to fix drift
due to
polar misalignment. It is ONLY intended to counter the slow
periodic back and
forth motion due to worm gear error. Do you understand why this is
so, and
why you cannot use PEC to "fix" polar misalignment drift?

If we can agree on the above, an it makes sense to you, we can
proceed to
what could perhaps be possible problems with the mounting.

7. Let us assume that you have polar aligned the mount properly,
but the
mount will not track a star for more than a few minutes. Now we
need to see
whether the motor is actually turning. Using the crosshairs of a
reticle
eyepiece, can you determine the drift rate? Is it 15 arc seconds
per second?
If so, the RA motor is totally stopped. You can see for yourself
very quickly
by removing the motor gear cover (the one with 6 small screws) and
see if the
motor shaft is turning. Is the motor shaft turning?

Perhaps the motor is turning, but doing so in an erratic manner.
This can be
caused by the worm gear being jammed into the worm wheel. Although
we do
everything possible to adjust the worm mesh, do to shipping
mishandling we
cannot always guarantee that the worm will not be forced into tight
mesh
because of some heavy blow the package received while being dropped
out of
the airplane onto the tarmack below. How do you check this? It is
exceeasy.
There is one gear in the motor gear train that is attached by a
screw. Remove
the screw, and pull the gear out. Now the motor runs free without
any load.
Now you can also check the worm pressure with your own fingers.
Simply turn
the little spur gear that is attached to the end of the qworm. Does
it move
smoothly, or do you need an Olympic wrestler or long crow bar to
turn it? If
it does not turn freely and smoothly, there you have your problem
of the
erratic motion. To fix it, you simply have to adjust the worm
tension. But
before you do that, you need to answer all the above questions so I
can get a
better idea of where your mount might be at fault.

8. There is a very slight chance that the drive rate of the mount
is not
correct due to a faulty motor drive circuit, but this is highly
unlikely. If
it is, there are a few things you can do in the control box to
trace this
down, but I would rather rule out all mechanical things first.

I hope this gives you enough information to start your analysis.
Please check
these things out, and if you have any questions, do not hesitate to
write to
me.

Roland Christen


O.K.Roland:
I will go step by step per your instructions. I do not blame the
chip, but actually the 1200 mount looks so impressive and rugged,
that I never even thought of a mechanical problem concerning the RA
gears. I will open the gear case to find out if it has a hard spot,
on the other mounts I have found those problems and fixed them qquite
easely.
As for the Moon, yes I know of the difficulties in tracking that
object due to the inherent movements an specially the declination
drift, but what I meant is that it was worse than the normal scenario.
I drift align using the normal procedure and sometimes the one Chuck
Vaughn uses, with a Star 20º N of the equator. After careful
aligning
using a 9mm or a 12.5 reticule eyepiece with sometimes a barlow, I
can wait for up to one to three hours and then check if the Star
still is in the E-W reticule line, then I assume it is well polar
aligned. I have never aligned the mount with the Hand Pad, what I
have done is to advance the time to get an orthogonal check with the
OTA on both sides of the meridian, so I know my telescope is as near
perfect as possible in orthogonalism.
I also know that the PEC just corrects the periodic error in the RA
gears, that is why I mentioned a "Right to Left" oscillation in the E-
W axis, I don´t expect to correct declinatio drift nor polar
misalignment.
I do not know if it is normal that when recalibrating and keeping the
button on, the mount moves very slowly and in step like manner in RA,
so please let me know.
I really want to thank you for your support and help, next weekend I
will try to give more details to you.
Sincerily,
Eric.


Re: Chip for 1200-GoTo

Roland Christen
 

In a message dated 3/12/2001 12:44:05 PM Pacific Standard Time,
eroelmx@... writes:


I do not know if it is normal that when recalibrating and keeping the
button on, the mount moves very slowly and in step like manner in RA,
so please let me know.
I don't know what you mean by keeping the button on. Are you depressing the E
or W button in 1x? in .5x? or in .25x? or 12x? or what? In any case, pressing
the E-W buttons should cause the star to move smoothly east or west at the
guiding rates. If you do not depress the button, does the mount track the
star at all? Or is there a jerky back and forth motion?

Roland Christen


Re: Calibration - 1200GTO

Joe Marietta <jmarietta@...>
 

Got it
Thanks again
Joe

----- Original Message -----
From: <chris1011@...>
To: <ap-gto@...>
Sent: Monday, March 12, 2001 10:17 AM
Subject: Re: [ap-gto] Re: Calibration - 1200GTO


In a message dated 3/12/2001 5:54:32 AM Pacific Standard Time,
jmarietta@... writes:


In the note below, you state, go to a 2-star calibration, enter a
star and press goto, then use the buttons to center the star.

Did you mean to say: first center the star with the buttons, then
press GOTO?

Aquire the first star by pushing the telescope manually to the star
position,
center it in the crosshairs, then press GOTO. If your mount is properly
polar
aligned already, you can then exit without going to the second star. If
you
wish to use a second star to polar align your mount, enter the star,
press
GOTO, then center it in the field with the alt-az adjusters. Do as many
iterations as you need to get an accurate alignment.

Roland Christen







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Tracking Problems Due to Inadvertent PEC Training

David H. Roberts
 

I suspect that this couldn't happen with an GTO mount, but it can (and
did) happen with my 400 QMD. While fiddling with the hand controller in
the dark, I accidentally engaged the PEC training without realizing it.
The result was that all of the motor-driven slews that I did over the
next few minutes were recorded as "corrections." As a result, the scope
could no longer track at all, as it followed the large "corrections"
that I had programmed in. It took quite a while to figure that one out.

......................................................................
. David H. Roberts .
. William R. Kenan, Jr. Professor of Astrophysics (781) 736-2846 .
. Physics Department, Yalem 326, MS-057 FAX: (781) 736-2915 .
. Brandeis University roberts@... .
. Waltham, MA 02454 USA http://pc.astro.brandeis.edu .
......................................................................


Re: Digest Number 246

David H. Roberts
 

ap-gto@... wrote:


To UNSUBSCRIBE, or for general information on the ap-gto list
see http://groups.yahoo.com/group/ap-gto
------------------------------------------------------------------------

There are 2 messages in this issue.

Topics in this digest:

1. Re: Chip for 1200-GoTo
From: eroelmx@...
2. Re: Re: Chip for 1200-GoTo
From: chris1011@...

________________________________________________________________________
________________________________________________________________________

Message: 1
Date: Sun, 11 Mar 2001 14:56:37 -0000
From: eroelmx@...
Subject: Re: Chip for 1200-GoTo

--- In ap-gto@y..., eroelmx@y... wrote:
--- In ap-gto@y..., chris1011@a... wrote:
In a message dated 3/10/2001 11:31:21 AM Pacific Standard Time,
eroelmx@y... writes:


I am having trouble with the tracking, PEC and goto.
Thanks,
In what way are you having trouble with the tracking, PEC and
Goto?
The new
chip does not change these functions. Are you properly polar
aligned? If not,
you will not track accurately in RA or Dec, and your Goto
accuracy
will be
poor. PEC will also not correct RA drift due to poor polar
alignment.

Roland Christen
Roland:
I have the mounting very well polar aligned, I have it permanently
mounted on a pier at the observatory. Also the OTA is orthogonal
with
mounting axes. Several months ago, I wrote Marjorie explaining her
what my problem is, but gladly I will explain it again.
1.- When you try to track a Star using sidereal speed, the star
keeps
wandering my reticule center (My scope has a 5000 focal lenght), so
with the 12.5 mm. reticule we are taking about 400X, it shows a
periodic error plus the Star drifts slowly away.
2.- When I try to train manually the Pec at this power, the trained
tracking is worse than with the PEC off, I have retrained it many
times but with no correction, I have even tried an St-4 guider for
training, I have trained my 12"LX200 with it and it tracks very
good.
3.- When I image planets at the prime focus (5000mm), I use an
HX516
ccd camera. I have used the solar tracking speed, though the
sidereal
speed works better. When you center the image, the planet starts
drifting right and left (periodic error) until finally the planet
slowly drifts away after 15 to 20 minutes. I have tried the PEC but
it tracks worse, so I am sticking to the sidereal tracking speed.
I also have the Digital Voice and works very good, but not the
tracking.
4.- When I use the Go-to function, I put a 45mm or 50mm eyepiece to
get around 100X to 111X and a wider field of view. I put the clock
on
time and because the mount is permanently fixed, I just go to a
Star
(not Planet or the Moon) and make a recalibration, just check that
the telescope was not moved since parked, I do another goto to a
near
object, usually is in the field, then I center it and hit the
recalibrate button, then the object begins to move very slowly if I
keep the button on, so what I do is just hit rapidly the
recalibrate
function and then the Menu.
Then if I go to another object, most of the time I will not find it
in the field.
Marjorie told me thatt he new chip would fix my problem, so that is
why I found this e-group web and wrote you.
My mounting has the electronics on top of the R.A. axis with the
plugs facing south, I think the new model looks up.
So as you see I have some problems with my mount, hope you can help
me fix them.
I send my best regards,
Eric Roel.
Roland:
I forgot to tell you that in #4.-, when I do the first or subsequent
recalibrations, if I keep the button on the object it moves step-like
and very slowly. When imaging the Moon, the tracking error is much
worse than with Planets and Stars, even using Lunar tracking speed,
actually it looks like there is no difference using any of the
available tracking speeds. I use 600 for slewing, that way the motors
do not wear too much, aside of that the mount is free, the dampers
are well tightened as not to stop the axes but just enough to have a
nice soft feel. I always do a drift align every month or so, so I can
tell you that the mount is well polar aligned.
In the same observatory I have a 12"LX200 and one of your 6"
f/12 "Superplanetary" triplet refractors, mounted on an HGM-200
equiped with the "Gemini" goto system, both telescopes can track
incredibly well, even that the LX200 has toy electric motors (tough I
did make the axes orthogonal using a laser, changed the declination
teflon bearings for needle bearings, took out the image shift using
bearings and taking the mirror flop out), the Gemini tracks like
anything I have ever seen, it keeps the object for hours without
drifting at all, before the Gemini installation it step-tracked. That
is why I expect much more from your flagship mount, now I just use it
for Moon and Planetary imaging using sub second integrations due to
the poor tracking. Hope this helps to see what is wrong.
Thanks, Eric.
________________________________________________________________________
________________________________________________________________________

Message: 2
Date: Sun, 11 Mar 2001 22:58:19 EST
From: chris1011@...
Subject: Re: Re: Chip for 1200-GoTo

In a message dated 3/10/01 7:13:33 PM Central Standard Time,
eroelmx@... writes:

<<
> > I am having trouble with the tracking, PEC and goto.
> > Thanks, >>

Ok, after reading your other two emails, I believe you have trouble with the
tracking, pec and goto. But you give me no information to make an accurate
diagnosis of your problems. Obviously, if all our mounts had this trouble, we
would not sell any. On one hand, I can probably explain everything you see on
improper setup, without blaming the mount at all, which would maybe not be
correct. I am not there, so I cannot check things out for you. You will have
to be my eyes and ears, and tell me what you see based on waht I tell you in
this Email and following ones.

1. It is easy and tempting to explain all faults by saying something is wrong
with the chip. That may or may not be the case. As an example, in an
automobile, there is a chip that controls a lot of functions. Let's say the
car runs rough and also won't go straight down the road, instead keeps
heading for the ditch. A good mechanic would check out the spark plugs and
wires, and also the wheel alignment, tire pressure, and perhaps ask if the
driver really had his hands on the wheel while driving. So, for now, lets
forget about changing the chip, and try to weed out the herrings from the
mackerel.

2. The mount won't rack the Moon. Well, I would expect that. The Moon does
not have one tracking rate, neither does it track parallel to the earth. I
have done a lot of lunar photography, and can tell you that you cannot track
the Moon accurately with any kind of mount without changing the altitude and
azimuth alignment. The Moon is a special case, that is not adequately covered
in any book that I know of. It would seem that one could dial in a lunar
rate, and the Moon would stay still in the eyepiece. At low power, yes. At
high power, not at all. The Moon's distance from the earth varies from day to
day, so the rate at which it moves from east to west varies also. There is no
one lunar rate. The Moon also moves up and down in its orbit, sometimes beign
high in the sky, other times being very low. The Moon's orbit is not parallel
to the earth, so simple polar alignment will not follow the Moon's motion.
There will always be declination drift, as the Moon moves between its
northern and southern nodes. If you want the Moon to stay still at high
powers, you will have to radically change both the elevation of your polar
axis, and the azimuth angle. Otherwise, it will slowly drift away in your CCD
camera field. I do this whenever I want to precision high resolution
photography of the Lunar surface. One would think that the dec drift could be
counteracted by following it with the dec motor. This is difficult to do
smoothly because there is a limit to how slowly a servo motor can be run
before it becomes almost stepper like in its action. The drift in Dec and RA
is many times slower than the sidereal rate ( varying between 3 to 20 times
slower), that no single motor circuit can be built to smoothly and accurately
follow this motion, and also slew at 1200 times sidereal. The mount would
have to have 2 sets of motors, one for slewing, and one for very slow
motions. This means 4 gears etc.

So, at this point, I say that the Moon is a special case, a red herring, so
to speak, that is not the fault of the mount, no matter how much you like it
to be.

3. Slow RA drift. In 99% of the cases where a mount will not follow the stars
for a period of time, the person did not polar align it properly. Do you
understand that this can be the case? In fact, one way TO polar align a mount
is to monitor the RA drift over time, and correct the altitude angle of the
polar axis. Did you do this to the 1200 mount? The mount cannot do this by
itself, it is somethign the user must do. Please do not rely on the Polar
routine in the keypad, it is only approximate. At the powers you are using
your telescope, you must drift align. Did you drift align the Polar axis?

4. Slow Dec drift. Same thing applies here. A slow dec drift is always caused
by the azimuth axis being aimed wrong. The dec axis will not "drift" due to
faulty motors or chips, the motors are not turning in the dec axis, unless
you want to go somewhere else.

5. The GOTO does not accurately place the object in the field of view. If the
mount is not polar aligned, I would expect exactly that. Also, what affects
GOTO accuracy on a German mount is the degree to which your telescope is
orthogonal to the polar axis.

6. The PEC will not "fix" the star drift. If the mount is not properly polar
aligned, I would expect that too. PEC is not intended to fix drift due to
polar misalignment. It is ONLY intended to counter the slow periodic back and
forth motion due to worm gear error. Do you understand why this is so, and
why you cannot use PEC to "fix" polar misalignment drift?

If we can agree on the above, an it makes sense to you, we can proceed to
what could perhaps be possible problems with the mounting.

7. Let us assume that you have polar aligned the mount properly, but the
mount will not track a star for more than a few minutes. Now we need to see
whether the motor is actually turning. Using the crosshairs of a reticle
eyepiece, can you determine the drift rate? Is it 15 arc seconds per second?
If so, the RA motor is totally stopped. You can see for yourself very quickly
by removing the motor gear cover (the one with 6 small screws) and see if the
motor shaft is turning. Is the motor shaft turning?

Perhaps the motor is turning, but doing so in an erratic manner. This can be
caused by the worm gear being jammed into the worm wheel. Although we do
everything possible to adjust the worm mesh, do to shipping mishandling we
cannot always guarantee that the worm will not be forced into tight mesh
because of some heavy blow the package received while being dropped out of
the airplane onto the tarmack below. How do you check this? It is exceeasy.
There is one gear in the motor gear train that is attached by a screw. Remove
the screw, and pull the gear out. Now the motor runs free without any load.
Now you can also check the worm pressure with your own fingers. Simply turn
the little spur gear that is attached to the end of the qworm. Does it move
smoothly, or do you need an Olympic wrestler or long crow bar to turn it? If
it does not turn freely and smoothly, there you have your problem of the
erratic motion. To fix it, you simply have to adjust the worm tension. But
before you do that, you need to answer all the above questions so I can get a
better idea of where your mount might be at fault.

8. There is a very slight chance that the drive rate of the mount is not
correct due to a faulty motor drive circuit, but this is highly unlikely. If
it is, there are a few things you can do in the control box to trace this
down, but I would rather rule out all mechanical things first.

I hope this gives you enough information to start your analysis. Please check
these things out, and if you have any questions, do not hesitate to write to
me.

Roland Christen

________________________________________________________________________
________________________________________________________________________

Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
--
......................................................................
. David H. Roberts .
. William R. Kenan, Jr. Professor of Astrophysics (781) 736-2846 .
. Physics Department, Yalem 326, MS-057 FAX: (781) 736-2915 .
. Brandeis University roberts@... .
. Waltham, MA 02454 USA http://pc.astro.brandeis.edu .
......................................................................


Re: Calibration - 1200GTO

Joe <jmarietta@...>
 

Hi Roland,

Finally had a clear night to test out this calibration message you
send me back in Feb.

I wanted to ask you the following:

In the note below, you state, go to a 2-star calibration, enter a
star and press goto, then use the buttons to center the star.

Did you mean to say: first center the star with the buttons, then
press GOTO?

Thanks

Joe



--- In ap-gto@y..., chris1011@a... wrote:
In a message dated 2/9/01 4:20:44 PM Central Standard Time,
jmarietta@e... writes:

<< Why can't you simply find a star and sync
the mount? >>

You can. Go to 2 star, enter a star, press goto, with the buttons,
center the
star in your eyepiece, then exit. You are done. In the new version
3, you
will be able to also manually push the scope to a star, center it
in the
eyepiece with the buttons, find the star in the star list and press
sync. You
are done. The objects you can sync on will include the solar system
objects,
as well as all stars and deep sky objects in any of the menus.

Roland Christen


Re: Calibration - 1200GTO

Roland Christen
 

In a message dated 3/12/2001 5:54:32 AM Pacific Standard Time,
jmarietta@... writes:


In the note below, you state, go to a 2-star calibration, enter a
star and press goto, then use the buttons to center the star.

Did you mean to say: first center the star with the buttons, then
press GOTO?

Aquire the first star by pushing the telescope manually to the star position,
center it in the crosshairs, then press GOTO. If your mount is properly polar
aligned already, you can then exit without going to the second star. If you
wish to use a second star to polar align your mount, enter the star, press
GOTO, then center it in the field with the alt-az adjusters. Do as many
iterations as you need to get an accurate alignment.

Roland Christen


Re: Chip for 1200-GoTo

Roland Christen
 

In a message dated 3/10/01 7:13:33 PM Central Standard Time,
eroelmx@... writes:

<<
> > I am having trouble with the tracking, PEC and goto.
> > Thanks, >>

Ok, after reading your other two emails, I believe you have trouble with the
tracking, pec and goto. But you give me no information to make an accurate
diagnosis of your problems. Obviously, if all our mounts had this trouble, we
would not sell any. On one hand, I can probably explain everything you see on
improper setup, without blaming the mount at all, which would maybe not be
correct. I am not there, so I cannot check things out for you. You will have
to be my eyes and ears, and tell me what you see based on waht I tell you in
this Email and following ones.

1. It is easy and tempting to explain all faults by saying something is wrong
with the chip. That may or may not be the case. As an example, in an
automobile, there is a chip that controls a lot of functions. Let's say the
car runs rough and also won't go straight down the road, instead keeps
heading for the ditch. A good mechanic would check out the spark plugs and
wires, and also the wheel alignment, tire pressure, and perhaps ask if the
driver really had his hands on the wheel while driving. So, for now, lets
forget about changing the chip, and try to weed out the herrings from the
mackerel.

2. The mount won't rack the Moon. Well, I would expect that. The Moon does
not have one tracking rate, neither does it track parallel to the earth. I
have done a lot of lunar photography, and can tell you that you cannot track
the Moon accurately with any kind of mount without changing the altitude and
azimuth alignment. The Moon is a special case, that is not adequately covered
in any book that I know of. It would seem that one could dial in a lunar
rate, and the Moon would stay still in the eyepiece. At low power, yes. At
high power, not at all. The Moon's distance from the earth varies from day to
day, so the rate at which it moves from east to west varies also. There is no
one lunar rate. The Moon also moves up and down in its orbit, sometimes beign
high in the sky, other times being very low. The Moon's orbit is not parallel
to the earth, so simple polar alignment will not follow the Moon's motion.
There will always be declination drift, as the Moon moves between its
northern and southern nodes. If you want the Moon to stay still at high
powers, you will have to radically change both the elevation of your polar
axis, and the azimuth angle. Otherwise, it will slowly drift away in your CCD
camera field. I do this whenever I want to precision high resolution
photography of the Lunar surface. One would think that the dec drift could be
counteracted by following it with the dec motor. This is difficult to do
smoothly because there is a limit to how slowly a servo motor can be run
before it becomes almost stepper like in its action. The drift in Dec and RA
is many times slower than the sidereal rate ( varying between 3 to 20 times
slower), that no single motor circuit can be built to smoothly and accurately
follow this motion, and also slew at 1200 times sidereal. The mount would
have to have 2 sets of motors, one for slewing, and one for very slow
motions. This means 4 gears etc.

So, at this point, I say that the Moon is a special case, a red herring, so
to speak, that is not the fault of the mount, no matter how much you like it
to be.

3. Slow RA drift. In 99% of the cases where a mount will not follow the stars
for a period of time, the person did not polar align it properly. Do you
understand that this can be the case? In fact, one way TO polar align a mount
is to monitor the RA drift over time, and correct the altitude angle of the
polar axis. Did you do this to the 1200 mount? The mount cannot do this by
itself, it is somethign the user must do. Please do not rely on the Polar
routine in the keypad, it is only approximate. At the powers you are using
your telescope, you must drift align. Did you drift align the Polar axis?

4. Slow Dec drift. Same thing applies here. A slow dec drift is always caused
by the azimuth axis being aimed wrong. The dec axis will not "drift" due to
faulty motors or chips, the motors are not turning in the dec axis, unless
you want to go somewhere else.

5. The GOTO does not accurately place the object in the field of view. If the
mount is not polar aligned, I would expect exactly that. Also, what affects
GOTO accuracy on a German mount is the degree to which your telescope is
orthogonal to the polar axis.

6. The PEC will not "fix" the star drift. If the mount is not properly polar
aligned, I would expect that too. PEC is not intended to fix drift due to
polar misalignment. It is ONLY intended to counter the slow periodic back and
forth motion due to worm gear error. Do you understand why this is so, and
why you cannot use PEC to "fix" polar misalignment drift?

If we can agree on the above, an it makes sense to you, we can proceed to
what could perhaps be possible problems with the mounting.

7. Let us assume that you have polar aligned the mount properly, but the
mount will not track a star for more than a few minutes. Now we need to see
whether the motor is actually turning. Using the crosshairs of a reticle
eyepiece, can you determine the drift rate? Is it 15 arc seconds per second?
If so, the RA motor is totally stopped. You can see for yourself very quickly
by removing the motor gear cover (the one with 6 small screws) and see if the
motor shaft is turning. Is the motor shaft turning?

Perhaps the motor is turning, but doing so in an erratic manner. This can be
caused by the worm gear being jammed into the worm wheel. Although we do
everything possible to adjust the worm mesh, do to shipping mishandling we
cannot always guarantee that the worm will not be forced into tight mesh
because of some heavy blow the package received while being dropped out of
the airplane onto the tarmack below. How do you check this? It is exceeasy.
There is one gear in the motor gear train that is attached by a screw. Remove
the screw, and pull the gear out. Now the motor runs free without any load.
Now you can also check the worm pressure with your own fingers. Simply turn
the little spur gear that is attached to the end of the qworm. Does it move
smoothly, or do you need an Olympic wrestler or long crow bar to turn it? If
it does not turn freely and smoothly, there you have your problem of the
erratic motion. To fix it, you simply have to adjust the worm tension. But
before you do that, you need to answer all the above questions so I can get a
better idea of where your mount might be at fault.

8. There is a very slight chance that the drive rate of the mount is not
correct due to a faulty motor drive circuit, but this is highly unlikely. If
it is, there are a few things you can do in the control box to trace this
down, but I would rather rule out all mechanical things first.

I hope this gives you enough information to start your analysis. Please check
these things out, and if you have any questions, do not hesitate to write to
me.

Roland Christen


Re: Chip for 1200-GoTo

eroelmx@...
 

--- In ap-gto@y..., eroelmx@y... wrote:
--- In ap-gto@y..., chris1011@a... wrote:
In a message dated 3/10/2001 11:31:21 AM Pacific Standard Time,
eroelmx@y... writes:


I am having trouble with the tracking, PEC and goto.
Thanks,
In what way are you having trouble with the tracking, PEC and
Goto?
The new
chip does not change these functions. Are you properly polar
aligned? If not,
you will not track accurately in RA or Dec, and your Goto
accuracy
will be
poor. PEC will also not correct RA drift due to poor polar
alignment.

Roland Christen
Roland:
I have the mounting very well polar aligned, I have it permanently
mounted on a pier at the observatory. Also the OTA is orthogonal
with
mounting axes. Several months ago, I wrote Marjorie explaining her
what my problem is, but gladly I will explain it again.
1.- When you try to track a Star using sidereal speed, the star
keeps
wandering my reticule center (My scope has a 5000 focal lenght), so
with the 12.5 mm. reticule we are taking about 400X, it shows a
periodic error plus the Star drifts slowly away.
2.- When I try to train manually the Pec at this power, the trained
tracking is worse than with the PEC off, I have retrained it many
times but with no correction, I have even tried an St-4 guider for
training, I have trained my 12"LX200 with it and it tracks very
good.
3.- When I image planets at the prime focus (5000mm), I use an
HX516
ccd camera. I have used the solar tracking speed, though the
sidereal
speed works better. When you center the image, the planet starts
drifting right and left (periodic error) until finally the planet
slowly drifts away after 15 to 20 minutes. I have tried the PEC but
it tracks worse, so I am sticking to the sidereal tracking speed.
I also have the Digital Voice and works very good, but not the
tracking.
4.- When I use the Go-to function, I put a 45mm or 50mm eyepiece to
get around 100X to 111X and a wider field of view. I put the clock
on
time and because the mount is permanently fixed, I just go to a
Star
(not Planet or the Moon) and make a recalibration, just check that
the telescope was not moved since parked, I do another goto to a
near
object, usually is in the field, then I center it and hit the
recalibrate button, then the object begins to move very slowly if I
keep the button on, so what I do is just hit rapidly the
recalibrate
function and then the Menu.
Then if I go to another object, most of the time I will not find it
in the field.
Marjorie told me thatt he new chip would fix my problem, so that is
why I found this e-group web and wrote you.
My mounting has the electronics on top of the R.A. axis with the
plugs facing south, I think the new model looks up.
So as you see I have some problems with my mount, hope you can help
me fix them.
I send my best regards,
Eric Roel.

Roland:
I forgot to tell you that in #4.-, when I do the first or subsequent
recalibrations, if I keep the button on the object it moves step-like
and very slowly. When imaging the Moon, the tracking error is much
worse than with Planets and Stars, even using Lunar tracking speed,
actually it looks like there is no difference using any of the
available tracking speeds. I use 600 for slewing, that way the motors
do not wear too much, aside of that the mount is free, the dampers
are well tightened as not to stop the axes but just enough to have a
nice soft feel. I always do a drift align every month or so, so I can
tell you that the mount is well polar aligned.
In the same observatory I have a 12"LX200 and one of your 6"
f/12 "Superplanetary" triplet refractors, mounted on an HGM-200
equiped with the "Gemini" goto system, both telescopes can track
incredibly well, even that the LX200 has toy electric motors (tough I
did make the axes orthogonal using a laser, changed the declination
teflon bearings for needle bearings, took out the image shift using
bearings and taking the mirror flop out), the Gemini tracks like
anything I have ever seen, it keeps the object for hours without
drifting at all, before the Gemini installation it step-tracked. That
is why I expect much more from your flagship mount, now I just use it
for Moon and Planetary imaging using sub second integrations due to
the poor tracking. Hope this helps to see what is wrong.
Thanks, Eric.


Re: Chip for 1200-GoTo

eroelmx@...
 

--- In ap-gto@y..., chris1011@a... wrote:
In a message dated 3/10/2001 11:31:21 AM Pacific Standard Time,
eroelmx@y... writes:


I am having trouble with the tracking, PEC and goto.
Thanks,
In what way are you having trouble with the tracking, PEC and Goto?
The new
chip does not change these functions. Are you properly polar
aligned? If not,
you will not track accurately in RA or Dec, and your Goto accuracy
will be
poor. PEC will also not correct RA drift due to poor polar
alignment.

Roland Christen
Roland:
I have the mounting very well polar aligned, I have it permanently
mounted on a pier at the observatory. Also the OTA is orthogonal with
mounting axes. Several months ago, I wrote Marjorie explaining her
what my problem is, but gladly I will explain it again.
1.- When you try to track a Star using sidereal speed, the star keeps
wandering my reticule center (My scope has a 5000 focal lenght), so
with the 12.5 mm. reticule we are taking about 400X, it shows a
periodic error plus the Star drifts slowly away.
2.- When I try to train manually the Pec at this power, the trained
tracking is worse than with the PEC off, I have retrained it many
times but with no correction, I have even tried an St-4 guider for
training, I have trained my 12"LX200 with it and it tracks very good.
3.- When I image planets at the prime focus (5000mm), I use an HX516
ccd camera. I have used the solar tracking speed, though the sidereal
speed works better. When you center the image, the planet starts
drifting right and left (periodic error) until finally the planet
slowly drifts away after 15 to 20 minutes. I have tried the PEC but
it tracks worse, so I am sticking to the sidereal tracking speed.
I also have the Digital Voice and works very good, but not the
tracking.
4.- When I use the Go-to function, I put a 45mm or 50mm eyepiece to
get around 100X to 111X and a wider field of view. I put the clock on
time and because the mount is permanently fixed, I just go to a Star
(not Planet or the Moon) and make a recalibration, just check that
the telescope was not moved since parked, I do another goto to a near
object, usually is in the field, then I center it and hit the
recalibrate button, then the object begins to move very slowly if I
keep the button on, so what I do is just hit rapidly the recalibrate
function and then the Menu.
Then if I go to another object, most of the time I will not find it
in the field.
Marjorie told me thatt he new chip would fix my problem, so that is
why I found this e-group web and wrote you.
My mounting has the electronics on top of the R.A. axis with the
plugs facing south, I think the new model looks up.
So as you see I have some problems with my mount, hope you can help
me fix them.
I send my best regards,
Eric Roel.


Chip for 1200-GoTo

eroelmx@...
 

Roland:
I own one of your 1200 GoTo mounts, I would like to know about the
new chip, I am having trouble with the tracking, PEC and goto.
Thanks,
Eric.


Stiff axis 600E

Joe Morris <joemorris@...>
 

Both the dec. and RA axis are so stiff when released that it's hard to
tell if they are properly balanced. Any suggestions to correct this?


latitude adjustment

Colt Bednorz <colt@...>
 

Roland and the group,

Maybe I don't read so well. I thought that I read in the 1200
manual that to change the latitude I had to unbolt things and
move the entire assembly to another hole and rebolt something,
in other words take the R.A. assembly apart.
Well, all you do is loosen a knob and turn another knob
In light of how simple this was, the answers I received
were incredibly polite.
"You turn a knob you idiot" would have been my answer.<vbg>
Maybe someone did say this. <g>
After setting the latitude, and sighting through the bore hole
even with no polar scope, I ended up with incredibly minor drift
adjustments. I spent about an hour and a half drift aligning,
and the results were very good. It didn't take this long, I adjusted
between reruns of the Sopranos. <g>
The mount behaves wonderfully and tracks as I expected- perfect.
Now I can see how Ray was able to get those unguided H-a
images with his small refractor. The star sat on the cross hairs
of an illuminated reticule for 3/4 of an hour long episode.
I wouldn't ordinarily post this, but the list seems a little slow today.

Colt Bednorz

P.S. How are those 250 mm refractors comming along?
You could manufacture 10 of these provided that one of them is mine.


Lubricant leak AP900

C. G. Anderson
 

Also, my mount leaks a clear yellow oil from the seam between both
halves of both axis. Any else have this problem?

Chris
--
"They say travel broadens the mind.
So I went over the falls in a barrel"
T. Dolby


AP900GTO dec play

C. G. Anderson
 

My mount has always (as far back as I can remember) had quite a bit of
play in the declination axis. I called once and someone at AP talked me
through some sort of adjustment, but it seems to have worn off. Does
anyone know the procedure that could post it here?

Chris

--
"They say travel broadens the mind.
So I went over the falls in a barrel"
T. Dolby


Re: Chip for 1200-GoTo

Roland Christen
 

In a message dated 3/10/2001 11:31:21 AM Pacific Standard Time,
eroelmx@... writes:


I am having trouble with the tracking, PEC and goto.
Thanks,
In what way are you having trouble with the tracking, PEC and Goto? The new
chip does not change these functions. Are you properly polar aligned? If not,
you will not track accurately in RA or Dec, and your Goto accuracy will be
poor. PEC will also not correct RA drift due to poor polar alignment.

Roland Christen


Re: Stiff axis 600E

Roland Christen
 

In a message dated 3/10/2001 9:39:54 AM Pacific Standard Time,
joemorris@... writes:


Both the dec. and RA axis are so stiff when released that it's hard to
tell if they are properly balanced. Any suggestions to correct this?



Stiff lubricant on the gears perhaps.

Roland Christen