Switching Actuator Positions:
 

WARNING (for case of SPARO only): The Helium level in the SPARO Helium-4 reservoir should be no more than about half-full when making a course actuator switch.  This is because SPARO will be turned nearly horizontal during this process.

WARNING:  Check where the sun is.  The telescope should never point with 25 degrees of the sun.
If you want the current position of the sun, go to comsoft, select (position->planets->sun) and comsoft will display it for you.  VCS will also display the position of the sun with the position::sunNow command.

The coarse actuator should only be moved when the fine actuator is near its lower limit for the currently available range.  Ignoring this constraint could lead to the screws hitting one another.  There are some hardware interlocks to prevent this from happening, but you should always be careful when changing actuator positions.

The coarse actuator box will not allow you to move the coarse actuator until a magnetic limit switch trips on the top of the fine actuator.  The current upper and lower actuator positions to trip this switch are approx. -44.0 in the upper actuator position and approx. -0.68 in the lower actuator position.  The exact values are written on the comsoft monitor.

If you need to stop the telescope from moving for any reason, any of the big red STOP switches will work, as will the power switch on the coarse elevation box.

Moving the Coarse Actuator (upper to lower):

  1. For case of SPARO only: Remove the flow meter attachment from the Helium-4 fill tube of SPARO.
  2. Turn on the power switch on the coarse actuator box (top of Rack#3).  You must do this first so you will see the coarse actuator enable light, once the telescope reaches the correct position.
  3. Using comsoft, move to lower limit (near elevation = -44.0, see note on comsoft monitor)

    4. The green "coarse enable" light should come on, on the coarse actuator box.
  4. Disable the El techron by setting the power amp enable switch on the El PID box to the off position.
  5. Turn off the brake power supply (HP 6299)
  6. Check that the coarse actuator power supply (Lambda LK-361-FMOV at the bottom of Rack #3) is on.
  7. Initiate coarse actuator movement by pressing the toggle switch towards 'move to 0'.
  8. The telescope will stop at the other limit on its own.  When done, turn off the coarse elevation box, turn of the course actuator power supply (Lambda), and turn on the brake power supply (HP 6299).  Then press  F9  on the comsoft PC, and turn on the enable switch on the PID.
  9. Using comsoft, move the telescope back up to the desired elevation, and reinstall the flow meter attachment onto the Helium-4 fill-tube on SPARO.

 

Moving the Coarse Actuator (lower to upper):

  1. For case of SPARO only: Remove the flow meter attachment from the Helium-4 fill tube of SPARO.
  2. Turn on the power switch on the coarse actuator box (top of Rack #3).  You must do this first so you will see the coarse actuator enable light, once the telescope reaches the correct position.
  3. Using comsoft, move to lower limit (near elevation = -0.68, see note on comsoft monitor).  [Note: this is in comsoft notation, ie  just above the horizon]

    4. The green "coarse enable" light should come on, on the coarse actuator box.
  4. Disable the El techron by setting the power amp enable switch on the El PID box to the off position.
  5. Turn off the brake power supply (HP 6299)
  6. Check that the coarse actuator power supply (Lambda LK-361-FMOV at the bottom of Rack #3) is on.
  7. Initiate coarse actuator movement by pressing the toggle switch towards 'move to 45'.
  8. The telescope will stop at the other limit on its own.  When done, turn off the coarse elevation box, turn of the course actuator power supply (Lambda), and turn on the brake power supply (HP 6299).  Then press  F9  on the comsoft PC, and turn on the enable switch on the PID.
  9. For case of SPARO only: Reinstall the flow meter attachment onto the Helium-4 fill-tube on SPARO.


If for some reason the coarse actuator gets stuck,  don't panic.  Go out and look at it to be sure it's not physically conflicting with anything. If not, you may have to apply some heat to it.  Rotate the telescope 180 degrees ( so the coarse actuator is facing the man door).  Go up, open the man door, extend the plank and examine the coarse actuator.  If there is nothing obviously wrong you might try applying heat to the ball-screw nut.  In the past two heat guns c-clamped to the telescope frame worked well as a heat source.

Again, BEWARE THE SUN!