Original manual text written by Wm. J. Wiegert.
This page is provided for customers who have purchased a No-Harm GoTo Dob telescope or major components thereof. Please feel free to comment on the accuracy of this information and/or provide suggestions for improvement. Changes can usually be made in a few minutes if need be.
Thanks
Lenord Stage
PRE-STARTUP INFORMATION
The steps involved in set-up and operation of your GOTO System are quite simple. However, you should read these instructions carefully, and do a “practice run” indoors (or in daylight) to familiarize yourself with the “feel” and location of all the components. For instance, the motor-cables are fitted with DB-9 connectors on each end. Both cable ends are female. In darkness it can be difficult to match their profiles to the male ends on the PCB for a proper connection. It is therefore strongly advised that you identify or mark these connectors in a way that will make it easy to mate them in dim light. Forcing them together incorrectly will damage the connectors, and adversely affect operation of the system. Color-coding is recommended (we suggest yellow and black – Note: red will of course be difficult to distinguish in red light).
THE CABLES
There are three (3) sets of cables:
A. One (1) “Telephone” cord
Connects the handpad to the control-box containing
the Printed Circuit Board
(PCB). It is Omni-directional.
NOTE: - This is NOT a standard phone cord. It is
a straight through data cord.
B. Two (2) Motor-Control cables with DB-9 connectors (9-pin).
One is for the ALT motor. One is for the AZ motor.
Both are light brown with
gray connectors on each end.
C. Power cables. (These are bundled from the PCB).
Two (2) battery clamps.
One BLACK (for the NEGATIVE battery
terminal). One RED (for the POSITIVE battery
terminal).
| NOTE: It is always advisable to connect & disconnect the NEGATIVE side first. |
Caution:
• There is only minimal strain-relief on these power cables.
• Handle them carefully.
• Always ensure slack.
• Avoid pulling or tugging.
THE HANDPAD – DESCRIPTION
There are
six buttons and one switch on the handpad. Four buttons represent back-and-forth
directions in each axis. The 2-position switch (in the center of the 4
directional buttons) toggles between slew speed and slow motion.
The other 2 buttons control many other functions such as the Grand
Tour mode. (In Grand Tour, Each time a button is pressed in one direction,
the telescope slews to the next object in the Tour. Conversely, if the
other button is pressed, the telescope slews back to the previous object).
To utilize the handpad, all the cables must be connected, and the program must be running. Connect the cables as described above in STEP 1.
SYSTEM SETUP
1.) Place the Azimuth (Az) axis base on a level surface.
a.) This doesn't need to be a “scientific” endeavour. Just ensure that the base is as level as possible and practical. We suggest using a carpenter's level if in doubt. Get the base as close to level as you can. The Az. Base is equipped with levering feet to assist you.2.) Place the Rocker Box on the Az base. Make use of the locators (depressions) provided.
3.) Ensure that the manual Az axis Placement-Bolt is loose.
a.) Move the Rocker Box manually so that the front side is facing close to South. The Altitude gear train should be to the west.4.) Connect the laptop and pcb to the battery or inverter as necessary. Connect the plugs to the pcb and laptop, if equipped, too. Make sure you do not touch either connector together.
b.) Snug up the Manual Placement-Bolt “hand-tight.” Do NOT over-tighten. This step protects against accidental bumping of the scope during use.
5.) Connect the motor cables to the motors and PCB. (The connector farthest from the spacebar on the laptop is the Alt. connection). A misconnection here will not result in damage. You can swap them out when you have the program and circuitry running.
DO NOT TURN ON THE PCB YET !
1.) Place the Tube (or Tube-Cradle if equipped) with the gear, inside the Rocker Box.
a.) Ensure that the gear slip-clutch is loosened, and that it is properly installed onto the axle (move it back and forth to be sure).2.) Point the tube horizontally.
3.) Make the tube exactly horizontal (use a level) and pointing due South.
4.) Tighten the slip-clutch on the Alt-gear. Ensure that the gear is properly meshed with the worm on the geartrain. Open the Alt geartrain cover to be sure. Position the blue gel so that it shields the stepper with the cover closed. In the future, you may find that it's not needed. Close the cover and latch it.
STARTUP
2.) Select option #3 (Type [3], then press any key). Ignore the on screen display items with the exception of the warning that tells you when to turn on the pcb !
3.) Turn on the PCB when prompted to do so.
INITIALIZING THE SYSTEM
1.) With the Optical Tube LEVEL, and pointing South, use the arrow keys
to highlight COORDINATES; select AltAz. Press [ENTER].
2.) Enter the values 0 (Zero) for Alt., 180 for Az.
3.) Arrow over to the RESET menu; select AltAz, and press [ENTER].
You can point the tube in any direction you wish as long as the AltAz coordinates are properly entered into the program. Remember, that with this system, Zero Alt is when the Optical Tube is HORIZONTAL, not vertical. This feature cannot be changed. |
ALIGNING THE SYSTEM
1.) Type [D] to bring up the DATA files.
2.) Select the [bstars.dat] file. This brings up the list of Bright
Stars for system-alignment. This option is usually [C].
3.) Select a bright star that you are familiar with, and that you can
see in the sky. Type its corresponding letter.
| For purposes of indoor trial and practice, it's advisable to use a planisphere, or to make an educated guess of where a star is located. This may prevent the system from seeking a star that is at Nadir (through the floor). |
4.) Use the handpad to slew the scope to the star you just selected.
a.) Use the Mode switch in the middle of the 4 buttons to toggle between slow-motion and slew speed.
b.) Notice which of the 4 direction buttons move the scope in each direction. Confirm this by looking at the left side of the center section of the main display. This is a good time to just move the scope around via the handpaddle.
| When you performed step #2 under INITIALIZATION, you told the program roughly where it was pointing. This is useful, as the Alt axis will only move 90 degrees. The program will not allow more movement than that which is preset in the config.dat file (90 degrees). You can edit this by opening the file in any text editor. Look in the [*** limit move section ***] |
5.) When you have the star roughly centered, but BEFORE you center it
EXACTLY, go to the laptop and select [hpmode].
6.) Type [B] (turns [init auto] ON). This tells the program via initialization,
that it is centered on the star that you just selected, and allows high
level function communication through the handpad.
7.) When the first star has been centered in the eyepiece at medium
power, press one of the two non-directional buttons.
a.) Look at the screen: The INIT section changes from 0 to 1 (first star alignment INITIALIZED). If not, press the other button.8.) After the first star is initialized, select another bright star from the dat files as done in step #1.
9.) Repeat steps #2 through #8. The INIT section should read “2”.
10.) If Tracking does not come on automatically, press [T]. This toggles Tracking on / off.
11.) To GoTo another object, select it from the dat files by pressing D.
12.) Press the number one to have the scope slew to that object.
ALTERNATE ALIGNMENT METHOD
1) Select option #2 at start up.
2) Point the scope as you usually would to Polaris
3) Select Polaris from the Bstars.dat file (press [D], then chose Polaris
from the Bstars.dat file.
4) Reset the Alt/Az coordinates from the reset menu
5) Reset the Equatorial coordinates.
6) Slew the scope via the handpad (via the motors, not manually) to
another bright star.
7) Press [D] then [C] to pull up the Bstars.dat file
8) Select the letter of the bright star you chose in step #6.
9) Arrow over to the Init menu.
10) Arrow down to the init2 item and press [ENTER]. (You can
later learn which button to press on the handpad to do this).
11) Press [D] and select an object to GoTo.
12. Press the number one (1) on the keyboard to slew the scope to the
selected object.
| This presupposes that you have entered your correct site coordinates (File/Site) and that they are accurate. This method of initialization is perfectly suitable for casual observing. If greater accuracy is desired, you can initialize on a third star or use the other procedure covered earlier in this manual. |
TRACKING AND FINDING OBJECTS
1.) Check to ensure that the system is tracking properly.
a.) The object or star should remain in the same place in the field of view, without drifting.
b.) The image should remain stable, and should not exhibit a “heartbeat” or a “pulse” in cadence with the sound of the motors.
| If the system tracks poorly or the target drifts rapidly out of the field of view, it is likely due to a one-star-only initialization, or the same star was used for both INITs. |
2.) Type [D] to bring up the data files.
a.) Select a category of objects, and then chose an object by typing its letter.3.) With the handpad in SLEW mode, GOTO the object you just selected.
4.) When the telescope stops moving look in the eyepiece, and verify that it's in the field of view.
5.) Re-center the object.
6.) When ready, type [D] again, and select another object.
7.) To view more objects, repeat steps # 2 through # 5.
TROUBLE SHOOTING
1.) Causes for poor operation:
a.) Wrong date or time (errors of plus or minus 12 hours are common)!
b.) Incorrect Latitude or Longitude.
c.) Wrong time zone, or incorrect input of daylight savings time.
d.) Poor backlash compensation. (See separate procedure on Backlash Compensation).
USER ADJUSTMENTS:
Unequal motor step-sizes can contribute to noise. Your motors were bench-tested and tuned to an elementary level, to ensure that all steps are reasonably equal. Minor improvement in step size accuracy can be made by the user, but it is only necessary if you anticipate long exposure (high magnification) CCD astrophotography. You can obtain details of the procedures to accomplish this on the scope-drive Yahoo Group archives.
STEPPER NOISE (continued)
Other user adjustments include motor torque, which can affect noise.
Here is a brief procedure:
1. Open scope.exe into the ‘equatorial’ mode, and select option #1.
2. Connect a stepper to the Az/RA connector and cable. You can do this
while the stepper is attached to the geartrain. We suggest using the Alt.
axis for this.
3. Press [T] and turn on the PCB as instructed by the software.
4. Open the Motors/MSParms menu item.
5. “What?? You gotta’ be kidding me!”
6. Calm down, this is not that difficult.
7. The two values you need look for are the MSDelay and MSPause. These
two are the power settings.
8. MSDelay is a coarse adjustment and MSPause is the fine adjustment.
9. Msdelay adjusts the pitch and MSPause adjusts the “volume”.
a. Notice the PWM value on the lower third of the main screen. It should read between 25-35. When you increase or decrease the MSDelay value (coarse adjustment) this value changes quickly.
b. When you increase or decrease the MSPause, (fine adjustment) the value changes slowly. Lower numerical values in MSPause correlate to higher current-draw from the battery, and higher pitched sounds from the motors. (Volume also increases with pitch).
c. We don't recommend using a value higher than 35. However some users run theirs as high as 200.
d. When you adjust the steppers in this fashion, you must note whether or not the worm shaft is moving while the scope is tracking during your adjustments. It is entirely possible to adjust out all of the torque from the steppers, (resulting in very quiet operation, but without any torque to operate the system).
BACKLASH COMPENSATION
Contributed by Jerry Pinter (Edited by Bill Wiegert)
| “Without backlash compensation, prior to every change of direction
for slewing, microstepping, and tracking, the motors will spin for awhile
and the [program] will think the scope is moving (and thus will change
the coordinates on the screen). However the scope [itself] is not yet moving.
This creates errors in pointing accuracy.
“Backlash can cause serious slewing, finding and tracking errors, especially if the backlash is a significant portion of the field of view. “Also, when tracking an object for CCD imaging, if backlash is not compensated
for, the object will drift across the [field of view] before backlash is
taken up. With backlash properly compensated for (as described below),
everything is taken care of automatically. The [program] knows exactly
where the scope is pointing during initialization, resets, and slews. When
the scope slews to an object, [that] object will land on the CCD chip,
and tracking will start immediately after the motors take out the slop,
leaving the object in the same place within the field of view. It's important
to have the scope balanced (alt axis) since any imbalance will tend to
make the backlash appear only in one direction, which will [tend to spoil]
the backlash compensation.
|
|
A. The procedure is best done in full daylight, and with the aid of an assistant. B. A laser pointer taped to the scope is extremely helpful in performing this routine, (to project a dot onto a wall or fence). Or you can use an eyepiece equipped with a crosshair. C. In either case, put an eyepiece in the focuser. D. Have a pencil or some masking tape handy for marking reference points on the wall (to help determine when the dot or crosshair moves). E. Connect all wires and cables, and start the program as normal. Tracking must be OFF. |
1. Connect each stepper to the pcb, power up the laptop and select option
1 when prompted. Turn on the pcb power.
2. Press ‘m’ on the keyboard. This brings up a window that allows adjustment
of Microstepping speed.
| 3. IMPORTANT: Record the current number! Write it down! (You will need to retype it at Step 16). |
4. Type in a small number, (i.e. – 100, 200, or 300). This will enable
a finer and more accurate movement. Make certain that your motors will
turn that slow! Press ENTER.
5. Using the handpad, microstep for awhile in one direction. Move the
scope enough to take up any backlash. Then STOP. Remember which button
you just used!
6. If using a laser pointer, mark a line or place a strip of tape at
the dot. If using a crosshair eyepiece, guide an assistant in marking a
line or placing a strip of tape where the crosshairs intersect.
7. Press ‘r’ on the keyboard, then use an arrow key to highlight ‘HOME’.
8. Press ENTER. This zeros the Alt-Az coordinates.
9. Look in the eyepiece. Using the OPPOSITE handpad button, reverse
the motor direction. The motor will begin running but the scope will lag
behind. STOP IMMEDIATELY when the scope starts moving (when the laser-dot
or crosshair just begins to move on the image in the eyepiece).
10. Note that the Alt-Az reading is no longer Zero. Read and record
the new Alt-Az coordinates to determine your amount of backlash (in degrees).
11. Repeat this routine several times (the more – the better!) going
back-and-forth in opposite directions. Re-mark the location each time with
pencil or tape. Take your time. Record all the readings in EACH AXIS.
12. Calculate an AVERAGE for each axis.
• (Add the readings, then divide by the total number of readings).
| example: .100 + .300 + .200 + .100 + .100 = .800 divided by 5 = .160 |
13. Convert the AVERAGE to arcminutes (multiply it by 60).
| example: .160 X 60 = 9.60 arcminutes |
14. In the program, highlight “CONTROL” with the LEFT or RIGHT arrow
key.
15. Highlight the submenu item “BACKLASH” with the UP or DOWN arrow
key.
16. Enter the new Alt-Az values as prompted. Record these numbers elsewhere
for future reference.
| 17. IMPORTANT: Go back into the Microstepping screen (type ‘m’) and retype the original number you wrote down in step 2. |
• After entering the new backlash parameters, repeat the routine as
a test.
• The scope should now "take up the slack" prior to microstepping,
[and function as though backlash
was non-existent].
“[As a test], quickly depress [and release] a handpad pushbutton. You should hear the motors spin, but the scope should not move much at all, and the altaz coordinates should not change appreciably. Even though the motors are spinning to take up the backlash, the scope is not moving and [thus] the altaz coordinates do not change in value.”
JP/bw
STEPPER SPEED ADJUSTMENTS
If your scope has trouble when slewing, as in sputtering or stalling out completely, you may need to adjust the Half Step parameters (HSParms). Fear not, this is easy to do and requires nothing more than opening the program.
1. Open scope.exe to the Equatorial alignment,
option 1 at start up.
2. Turn on the pcb and have the steppers connected.
3. Highlight the motors/hsparms menu, press enter.
4. Press enter once to have the cursor blinking
at the Max Delay line. This value in parenthesis is the speed the steppers
start at when slewing. Typically 1000 is fine. You might raise that to
1200 or so. Type in 1200 and press enter.
5. Mindelay is the value given for the top slewing
speed of the motors. Whatever I have put there, add 300 to it to start.
6. Leave the next value alone. You need not type
anything, just press enter.
7. The next value is the HS Ramp. This is the
amount of time that it takes to go from the start speed to top slewing
speed. The value should be one or 2. Change it to 4.
8. Leave the next two values alone and just press
enter to leave the menu.
9 When the menu is clear, and you are back to
a normal screen, try slewing the scope with the handpaddle. If the steppers
don't stall or sputter, you have figured out the problem.
You can go back and lower the values you changed to get the maximum slewing speed out of the motors without stalling. For the Ramp, I like one or two for a value. You can use whatever you are comfortable with though.
The other values can be changed in increments
of 50 or so to get the fastest slew speed without stalling the motors.
TRACKING TORQUE ADJUSTMENTS
Should you find that the tracking is not working well, or at all, you may have adjusted out the torque in the motors to quiet them down. See the warning in step 9d of the stepper noise adjustment above.
HOT KEYS
ALL OF THE HOT KEYS CAN BE FOUND IN THE FILE MENU OF THE SCOPE PROGRAM.
EVOLUTION SETUP
The Evolution system will require a little set up and a little tweaking of the values inside the scope.exe program. Neither of these valuse is difficult to get, they only require a little patience and a couple of tools.
First is the stepsizes. This is the setting that tells the program when you have moved x number of degrees. It is a must for getting any kind of decent accuracy out of the program. This valuse is put into the Motors/AZStepsizes menu of the scope.exe program. You will need a decent carpenters level and a cheap laser pointer.
First, determine the gear ratio of the gearhead
for each axis. You should have been told what that is. If not, send an
e-mail to Lenord and find out. Second, you need the diameter of the Alt
bearing you are driving for the Alt value (and the diameter of the ground
board for the Az axis). Third, the number of steps per revolution your
steppers have. That value will be either 200 or 400 and should be marked
on the stepper face.
Now, take the three values and multiply them
together, in any order. That should look like this:
400 X 12 X 50 = 240,000 for an Alt axis
One of the numbers for the Az. axis will be the diameter of your ground board divided by the diameter of the Az splined roller.
Take the value and divide it into 1296000. (the number of arc seconds in a circle)
This time it will equal 5.4. the value should always be between about 2 and 12. If you get something strange, like .145 or something, and after an attempt to figure out what you did wrong, send Lenord an e-mail.
After you have the base values, input, follow the instructions for setting the backlash above.
After doing that, we will do the Alt axis as an example first here, affix the level to the end of your OTA/secondary cage. Set at completely vertical. Use the level to make sure it is "perfectly vertical" (pointed straight up). Reset the Alt axis coordinate value to zero and slew until the OTA is perfectly horizontal. You should have a value in the program close to 90 degrees. If it is of, you need to modify the Alt axis' AZstepsizes value until it reaches 90 when the Alt axis moves 90 degrees.
As you get closer to 90 degrees displayed when the axis is moved 90 degrees, you need to recalculate the backlash compensation to keep things accurate.
The laser pointer is used on the Az axis when you are slewing it around to determine the step size value. Just affix it to the rockerbox somewhere, turn it on and mark where it is pointed. That is your start and stop point. Alternatively, you can make a 90 degree mark on your ground board somewhere and use that.
Do remember to set the values to what they should be in the Motors/ReverseAZMtrs menu item. That value changes the coordinates from rising or lowering in value as each axis of the scope is moved. For those that don't know already:
In Azimuth: as the rockerbox moves clockwise, the coordinate value needs to rise in value. At 12 o'clock it needs to be zero. At 3 o'clock it needs to read 90 degrees etc.
In Altitude: When the OTA is pointed at Zenith, the value should increase as is goes to the horizontal position.
SOFTWARE UPDATES
From time to time Mel Bartels updates the scope.exe program. You can
always look for the current version of the program at his website
To update your software, it is really easy to do. All of the current
settings you have in the program, backlash, microstepping speed etc., all
stay with the program. This is what you need to do:
Make a backup copy of the scope.exe program and the config.dat file on a separate floppy disk. Save these in case something goes wrong.
Download the zipped file to your computer.
Unzip it into a directory.
Take ONLY the file called scope.exe from the archive and put it on
a floppy disk.
Take that file and overwrite the current version of scope.exe on your
scope computer.
Done.
For those of you that forgot how to do this in DOS, the instructions are below. I'll assume you can put a single file onto a floppy from a Win xx computer.
Insert the floppy
Open scope and exit until you get the c:/scope prompt
Type this: copy a:/scope.exe
DOS will ask if you want to overwrite the current version of scope.exe,
press Y
Type scope at c:/scope
The new scope version will open.
You can check to make sure this is the new version by looking at the
top line of the program for the compiled date.