Differences

This shows you the differences between two versions of the page.

--- hardware [2024/05/03 16:28] – astroadmin
+++ hardware [2025/08/13 18:20] (current) – holtz
@@ Line 7: / Line 7: @@
 Mounted on the side of the telescope is a 6" two-element refractor guide scope.
-Telescope communication and control is via a [[http://www.siderealtechnology.com/ |Sidereal Technology Servo Controller II]].
+The telescope was upgraded around 2010: the analog motors were replaced with digital servo motors, and the gear system replaced with a belt drive system, using 3/8" wide trapezoidal belts. On the RA drive, the motor wheel has 15 teeth, while the wheel on the RA worm has 30 teeth.
+Telescope communication and control is via a [[http://www.siderealtechnology.com/ |Sidereal Technology Servo Controller II]]. The Servo Controller II is located in the base of the telescope. Driver/receiver RS-422 extenders for the encoder connections were purchased from US Digital, with EA-R-L-10-W5 for the receivers and EA-D-L-10-??? for the drivers.
 Although the SciTech controller can independently control the telescope, we conntinue to power up the Boller and Chivens system for several reasons: 1) it activates the torque motors that may help to push against the worm drive, 2) it activates the telescope hardware horizon limits. There is a relay attached to one of the web power switches which turns on the telescope power. There is a second relay attached to a separate controllable outlet that can be used to override the hardware limits; this must be used only with great understanding and care!
@@ Line 55: / Line 58: @@
 Dome shutter power is provided by a 15W/1A amorphous solar panel (NPower 15W Solar 12V Battery Charger) on the exterior of the dome, approximately 90° to the right of the slit. This solar panel is protected with 1/4" plexiglass and a styrofoam shock absorber. There are two spare solar panels in the building. Power is routed through a charge controller (7A max) to a 12V battery mounted to the interior of the dome; if replacing this, make sure that the wires are secured such that they will not catch on anything during dome rotation. In case of emergency, a 12V battery trickle charger is stored in the computer room.
+The dome shutter has limit switches which are triggered at either end of travel by small ramps that are welded to the dome that push up on one of two roller switches mounted on the right side of the shutter. There is also a large double-direction switch that kills power to the motor in the event that the limit switches fail to do so through the control card, although this switch needs to be adjusted so that it gets triggered before the shutter is sufficiently closed to prevent further motion.
 The dome communicates with the other electronics via a magnetic induction loop. This is the thin wire on dowels on the ledge running around the bottom of the dome interior. Be careful around the wire, as it could break easily. Automation is provided by a [[http://diffractionlimited.com/product/maxdome-ii-observatory-dome-control-system/ |Diffraction Limited Maxdome II dome controller]]. The two Maxdome circuit boards are encased in metal boxes, one next to the manual rotation controls and one inside the manual slit control box. These circuit boards have status LEDs, visible through small holes in the boxes; this can be useful for troubleshooting. See below for more details on these cards
@@ Line 60: / Line 65: @@
 The dome rests on 13 4"x1.5" rolling bearing phenolic [[https://www.grainger.com/product/Caster-Wheel-4-in-Wheel-Dia-55KC34?opr=PDPDAM&analytics=msubItems_1G450&position=1|caster wheels]] (link updated on May 3rd, 2024) with a 1 5/8" hub length and 3/8" bore. The axles are 2.5" long hex bolts (3/8" diam, about half an inch of thread.) There is an approximately 5" clearance between the bottom of the dome and the ledge; a typical emergency tire-replacement jack is sufficient to raise the dome enough for wheel replacement. There are also several identical horizontal wheels, which are not load bearing.
-Jon and Zach replaced the wheel that is south of due east on May 3rd, 2024.
+Jon and Zach replaced the wheel that is south of due east on May 3rd, 2024. This failed again in early 2025, perhaps because the caster was compromised. New casters were purchased and welded into place by NMSU F&S, and new wheels installed (see maintenance log).
 Dome is controlled by ACP; don't connect to the dome in MaximDL. Note that the dome is set up such that it will automatically close if it does not detect a signal from the control computer; so if you're up there doing maintenance and open it to let some light in, make sure the computer is on so it doesn't close itself.