Background

This document descibes the procedure for turning off power to the DEIMOS science CCD array or the Flexure Compensation System (FCS) detector system.

Procedure

1. Log into deimosserver using the dmoseng account.
2. From the command line prompt in an xterm window, initiate a remote controlled shutdown of the DEIMOS science CCD controller analog power. To power down the DEIMOS science CCD controller, use either:

   	powerdown

   or

   	powerdown deiccd

   To power down the DEIMOS FCS CCD controller, use:

   	powerdown deifcs

   The script will ask you to confirm that you REALLY want to power down the DEIMOS science (deiccd) CCD controller. Answer either yes or YES and then hit the RETURN key.

   This command should, after a delay of about 40 seconds, cause the analog switches in the dewar electronics to open up (thus electrically isolating the CCD mosaic inside the dewar from the outside world) and then cause analog power (+35 volts, +16 volts, and -16 volts) to be removed from the backplane of the DEIMOS science CCD controller.

   This command takes about 1 minute to complete. When it is done, it will either confirm that the analog power down sequence was successful, or it will tell you why it was not. If the powerdown command did not succeed, then contact the DEIMOS instrument team in Santa Cruz for troubleshooting assistance.

Transcripts

Science CCD System

Here is a transcript of a successful completion of the DEIMOS powerdown command on the science CCD crate:

	
	**** WARNING ****
	CYCLING POWER ON THE CCD CONTROLLER WILL INJECT CHARGE INTO THE CCDS.
	THIS INJECTED CHARGE WILL TAKE 10 TO 20 HOURS TO DECAY AFTER POWER ON.
	YOU SHOULD AVOID POWERING DOWN THE CONTROLLER IF YOU ARE PLANNING TO
	OBSERVE WITH THIS CCD WITHIN THE NEXT 24 HOURS.
 
	ARE YOU SURE YOU WANT TO CONTINUE WITH THIS POWER DOWN SEQUENCE? (yes/no)
	yes
	
	Will proceed with power down sequence in 10 seconds

	Waiting 60 seconds for power down sequence to complete
 
	The CCD controller for service deiccd has been powered down
	It is now safe to turn off the main power switch on the front panel
	of the DEIMOS science CCD controller power supply chassis that is
	located in bay 8 of the DEIMOS electronics ring
 
      

FCS CCD System

Here is a transcript of a successful completion of the DEIMOS powerdown command on the FCS CCD crate:

	**** WARNING ****
	CYCLING POWER ON THE CCD CONTROLLER WILL INJECT CHARGE INTO THE CCDS.
	THIS INJECTED CHARGE WILL TAKE 10 TO 20 HOURS TO DECAY AFTER POWER ON.
	YOU SHOULD AVOID POWERING DOWN THE CONTROLLER IF YOU ARE PLANNING TO
	OBSERVE WITH THIS CCD WITHIN THE NEXT 24 HOURS.
 
	ARE YOU SURE YOU WANT TO CONTINUE WITH THIS POWER DOWN SEQUENCE? (yes/no)
	yes
 
	Will proceed with power down sequence in 10 seconds
 
	Powering down DEIMOS CCD controller service deifcs

	Waiting 60 seconds for power down sequence to complete
  
	The CCD controller for service deifcs has been powered down
	It is now safe to turn off the main power switch on the front panel
	of the DEIMOS FCS CCD controller chassis that is located 
	in bay 10 of the DEIMOS electronics ring
      

If the powerdown sequence is not successful, the following message will be shown in the terminal:

	Waiting 60 seconds for power down sequence to complete
	
	The +35 volt analog power for this controller did not turn off
	The +/- 15 volt analog power for this controller did not turn off
	The analog switches in the dewar did not open as commanded
 
	*** The power down sequence for DEIMOS CCD controller service deifcs
	*** was not successful.  Please call UCO/Lick at UC Santa Cruz
      

To power down the FCS CCD in an orderly manner when the command powerdown deifcs fails, modify the following keywords:

	modify -s deifcs utbn2fil=off
	modify -s deifcs utb30ven=disabled
	modify -s deifcs utb15ven=disabled
	modify -s deifcs utbn2htr=off
      

You can check that the system was powered down correctly by running again the commabnd powerdown deifcs. The output should be as follows:

	The CCD controller for service deifcs has already been powered down