Telescope Power

or, What needs to be powered on for telescope to work correctly.

• Power Rack:The rack at the base of the stairs, which contains power supplies for telescope motors and relays, ra drive, and ra preload.
• Relay Control Box:The large white cabinet just inside the hallway, which mostly contains relays necessary for telescope motion.
• 4x4 Control Box:The gray box on the wall next to the Relay Box, contains the logic cards for the shutter and filter wheel.

Also remember that the telescope brakes need air pressure -- make sure the breaker for the air compressor is on downstairs.

Power Rack There is a white breaker switch at the top right of this box. It needs to be in the up for normal observing. Next down in the rack is the telescope drive power supply Turn the knob to check the four voltages: neg hi: 250V (neg) pos hi: 250V neg low: 60 (neg) pos low: 60 Below the drive power supply is the preload motor supply. All four dials should read about midrange. Possible Problems: If the breaker is tripped or off there will be no telescope motion and there will be no mains or drive voltages sent to the to the relay box. If one or more of the supply voltages is not correct some of the set, search, or slew drive rates will be strange, and may only drive in one direction. Combinations of these voltages are applied to the motor windings to control both the RA and DEC motions. They also supply current to solenoids that switch the direction of search and slew in RA. They also power a solenoid in the DEC gearbox to switch from slow to fast motion. PH does not know how direction is changed in DEC drive.

Relay Cabinet The are three breakers inside the cabinet on the top left. Only the upper one is used at present. The top breaker should be switched to the left (on) for normal observing. The switched power for the 4x4 control box passes through this cabinet, but bypasses this breaker. See the to be written section on Handpaddles & Telescope control. In the meantime the basic components are labeled on this closeup of the interior. There are spares for most of the things that are likely to fail in the bottom of the cabinet.

4x4 Control Box If this box is not powered up and the RS232 cable connected then wombat will appear hung. There is an opto-isolator connected to the RS232 line on the inside of the box to prevent damage due to lightning strikes. A red reset button can be used to reboot the single board computer used to control the filterwheel/shutter. However this usually happens when the telescope power is cycled. This computer is programmed in forth, hence the weird word you type to move the filterwheel. Spares for many of the driver chips are either in the bottomof the cabinet or in the electronics lab.