Vixen SPHINX SXD Mount - Manual (Page 41)

Page 42
Backlash Compensation
Backlash is a momentary stoppage in the movement of the telescope due to a sluggish
engagement of the gears. It occurs when the direction of the movement is reversed. The
backlash does not occur while the telescope moves at constant tracking speed.
The backlash compensation can adjust time lag when the direction of the telescope
movement is reversed and it allows you to make smoother motor control for comfortable
operation. Nevertheless, some backlash is necessary for the motor to operate smoothly.
Checking the backlash compensation
To verify the amount of backlash compensation, it is easiest to use a bright planet, star of
the first magnitude or the Moon.
(1) Polar align the mount exactly so as to point the R.A. axis of the mount to the North Pole
(or South Pole) of the sky.
(2) Change the screen to SCOPE MODE, and down the speed of the telescope to the slowest
or the second slowest with the Zoom+ key.
(3) Center your target celestial object in the field of view of the telescope, and then press the
RA+ key to verify how the object moves in the field of view.
*It may not move immediately as you press the RA+ key. Continue pressing the key until
it starts moving.
(4) Press the R.A.- key to verify how it moves in the field of view.
If there is a time delay before the object start moving when you press the key, it indicates
that the amount of backlash compensation in the R.A. is too small. On the contrary, if the
object moves quickly and extensively as you press the key, it shows the amount of the
backlash compensation in the R.A. is too large.
(5) Next, press the DEC+ key and press the DEC- key in turn to verify how the object moves
in the field of view.