When power is applied to the SiTech controller and a handpad direction button is pressed,
the motor slowly increases, faster and faster until it's full speed.
The motor encoder is not supplying feedback. Check cabling, connectors, and encoder You
can swap the altitude and azimuth motors for testing. See if the problem follows the motor, or if the
problem remains. If the problem remains, there may be an issue with the controller. If it follows the
motor, it is definitely a wiring or encoder problem.
Motor runs away as soon as power is applied or commanded to move. After running fast for
a short time, it stops, and the light flashes.
The motor encoder relationship to the motor polarity is wrong. See section on “Setting Up
When commanded to move, the motor starts ramping up, then stops, and the LED flashes.
It could be that you are using higher voltage motors with only 12 volts applied to the
controller. Either slow down the speed, or use a higher voltage on the power to the controller.
Nothing works at all, and the two LED's are on very faintly.
There is a major problem with the CPU. If you were using version 1.3 or earlier, there was a
bug that allowed a remote chance of the flash memory to be erased. You will have to send the
controller back to the factory for a re-program.
Motor gets abnormally hot:
Check the motor current. You can do this using the ServoConfig software. The motor
current appears on the main screen. If more than 0.5 amp while the scope is moving slowly, you may
have more friction on the gear train, or maybe your scope is out of balance. Sometimes worm gears
add a lot of friction to a drive system. Be sure the thrust clearance on the worm is not too tight, and be
sure the worm pressure against the wormgear is not too much. Be sure lubricant is applied properly.
Upon applying power, one of the motors starts slewing, all by itself. Nothing will stop it.
Unplug the handpad and see if it still happens. If it stops moving, you've a faulty handpad.
If it keeps on moving, it may be there is a problem with the digital input for the handpad. Please
Handpad Operation Troubleshooting:
I'm using an old style handpad (the one with a center switch) and the scope only moves in
two directions instead of 4.
Check that the internal jumper is set properly for the old handpad.
Some of the switches don't work properly.
Use the ServoConfig software. At the main screen, look at the virtual handpad. Pressing
each handpad button should make the appropriate virtual button highlight. If not, check the handpad
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for problems. If the virtual handpad works properly, check the slew and pan rates.
DragNTrack & SlewNTrack modes:
I initialize on the zenith, then the celestial pole, but it doesn't track properly.
Maybe the firmware version of the SiTech controller is version 1.5 or lower. If so, please
upgrade to version 1.6 or later. There was a bug in the calculate latitude routine in versions 1.5 or
I live in the southern hemisphere, and the tracking is the wrong direction. I have initialized
on the Zenith, then the south celestial pole.
The SiTech controller has no way of knowing which hemisphere it's in when initializing on
the Zenith or the Altitude. You've got to set the Latitude to a negative number (using ServoConfig)
before it will work properly. Once a negative, the initialization process will always keep it a negative
I know the Latitude is correct, but it doesn't track properly.
1. If you've a clutched telescope, check for clutch slippage on tracking. Sometimes the
clutches will work on a slew, but will slip during tracking.
2. Double check the encoder and motor ticks per scope revolution for altitude and azimuth.
3. Be sure the scope encoder and motor encoder polarity is set up properly. You can do this at the
main screen of the ServoConfig program. While you watch the scope encoder and motor encoder
location for the altitude, raise the scope. Both the Scope encoder and the Motor encoder should
increase. Check also the azimuth. They should both increase when the scope moves from north to
It tracks fairly ok, but I think it should track better.
This could be caused by several factors, the most common one is celestial pole misalignment.
Use the maps provided in this document, and star hop to the celestial pole.
It could be that the latitude isn't set up properly.
It could be that your mount is not level in the north/south direction.
It could be that your drive system or encoders are slipping.
It could also be caused by the wrong values in the scope encoder configuration (or Motor Encoder if
using the SlewNTrack mode). To check this, use ServoConfig and from the main screen, keep clicking
on the “Get Angles” button. Start at the horizon then move the scope to the zenith. *It should have
moved 90 deg's. Do the same for the azimuth. Moving you scope clockwise will give you an increase,
starting at North, should be 0, then to the East as 90, South, is 180, West is 270, etc.
Also check the motor encoder ticks per rev. If these are wrong, the motors will operate at the wrong
rates. Keep in mind that the tracking math is proven, and it works great. When things are set up
properly, and you've a good mount with no slippage, the scope should track with only 3 or 4 arc
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minutes of drift per hour. Howard Banich can track an object at 450 power for an hour in his 28 inch
*Important Note: If you are using ServoConfig version 0.9, the Azimuth reads backwards from above
description when clicking on Get Angles!!!
The telescope doesn't track at all sometimes.
Solutions: 1. Press the top right key to turn tracking on or off.
2. Be sure it really is in the DragNTrack mode. LED 2 should turn on and off every 8 seconds or so. If
it does this, it really is in the DragNTrack (or SlewNTrack) mode. If it doesn't do this, the scope is not
in the DragNTrack or SlewNTrack mode.
Problem: I'm using an old style handpad (the one with a center switch) and the DragNTrack doesn't
Solution: If you are using an old style handpad, and you are using Servo version 1.5 or earlier, you
must enter negative values for the Slew and Pan rates. After you check this, be sure the scope moves
from north to east when pressing the right button, and be sure the scope moves up when pressing the up
I have an equatorial telescope. The telescope tracks fine for a while, then stops.
Using ServoConfig, increase the Platform Goal to a number greater than 9,999,999 or less
The equatorial mode works, but the direction is the wrong way.
Using ServoConfig, change the Platform Goal from positive to negative (or vice versa).
The equatorial mode works, but the stars drift in Right Ascension.
Check for slippage if a roller drive. Also check the Equatorial rate using ServoConfig.
Argo Navis™ mode:
The Argo Navis™ mode doesn't work at all. I pressed both top left and top right buttons
simultaneously. The encoder values don't change on the Argo Navis™ when I move the scope.
Controller firmware must be at least version 1.6. Argo Navis™ firmware should be at least
1.1.6 Check the serial cable. Check that the SiTech controller is configured for Argo Navis™. Check
that the Argo Navis™ Com Port is set up to run the SiTech command at startup. Check that the Argo
Navis™ serial port is set for 19200 baud.
I don't have encoders on my scope, and I'm trying to use the Argo Navis™, but the encoder
locations on the Argo Navis™ don't change when I move the scope.
Be sure the SiTech controller is in the SlewNTrack mode.
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I can do a normal Argo Navis™ Initialization, but the tracking and GoTo's are inaccurate.
Set up your telescope in the DragNTrack (or SlewNTrack if you don't have scope encoders)
mode. Be sure to get that working well. If the DragNTrack (or SlewNTrack) doesn't work properly,
neither will the Argo Navis™ mode. Be sure the Argo Navis™ is set up properly. Check the encoders
on the Argo Navis™. They should change at the same angles as you move the telescope. If not, check
the Argo Navis™ encoder resolution. It should be +18,000. Check the motor and scope encoder
values in the SiTech configuration. If necessary, use ServoConfig and Ticks Determination to find the
encoder values. Remember, the math in the Servo controller has been proven, time and time again, it is
a mechanical or a configuration problem.
When I do a slew, the telescope moves close to the object, then moves again about the same
distance in azimuth, or altitude.
Sounds like one of your scope encoders is not working properly. Check the scope encoders
and/or wiring. This is easiest using the ServoConfig main screen.
I have an equatorial mount, and I'm writing my own software to control the scope. The
declination doesn't guide properly.
The controller adds or subtracts the guide rate to the current rate. It is possible if your
declination motor is at it's destination, the guide mode gets mixed up. Try giving the motor a
command to move “far far away”, with a rate of ZERO. This should fix the problem. This is not an
issue with Servo version 1.6 or later.
The guiding doesn't seem to work properly.
Connect up the autoguider and try the test mode on your guiding software. Run the
ServoConfig software. Be sure each of the virtual handpad keys are highlighted when the guider is
guiding in a particular direction. Be sure that the SiTech controller is in the Guide mode.
It doesn't seem to guide at all, but it is panning or slewing when guide commands are sent.
Be sure it's in the guide mode. This is a software issue if using the ASCOM software or
ScopeII. If in DragNTrack or Equatorial mode, hold down the top right key, and press the right key to
toggle the guide mode. If you are using the Radio Handpad Reciever, and are using the guiding input
provided, this shouldn't be a problem, because the controller will automatically