Troubleshooting guide

Wheel]. The script ends by saying that the time for the wheel's motion to complete has expired.
The Initialize Wheels button will execute the script engineering.config.filter.grism.decker.wheels.pl, which
will rotate the wheels until the home position switch is activated, tell the controller to zero the position,
and then move to the commanded position. We refer to this as a home-type of limit, or limit switch
operation. The Move Wheels and Move MOS Wheel commands operate in a relative mode, and it will
move the relative number of steps from one position to another, with a small overshoot and reversal to
correct for backlash. We usually recommend the Initialize Wheels button for the first motion of those
wheels, then use the Move Wheels button because the motions are shorter. Since the MOS wheel does
not have an operating limit switch, the relative motion command must be used for all motions.
There are two modes of failure for each wheel.
(1) The limit switch fails to engage. If the wheel operates with a limit-switch home type, then the
wheel can spin endlessly, and the perl script will just give up after some time limit. If you can stop
the wheel and determine the location of the mechanism, it is possible to recover from such a failure
and then use the config.rel.mv.filter.grism.decker.wheels.pl [Move Wheels] command for relative
motion..
(2) The wheel binds, and a grinding noise is audible if you stand next to the dewar. If this happens
there usually is no quick recovery after you have stopped the motor.
Solutions:
a) First, you must stop the wheel that is either spinning endlessly, or is jammed.
1. Type CTRL-Z, type jobs, kill -9 %<jobnumber> if the perl script has not yet finished and you
already know that there is a problem.
2. Type ufmotor -host flmn-2m-1a -port 52004
a) At the motor prompt, type <motor_name>@, where <motor_name> is one of letters a, b, c,
d, or e, where motor a = decker, b = mos, c = filter, d = lyot, and e = grism. This should do a
soft-stop of the motor.
b) Type exit to quit ufmotor.
3. Type turn.off.motor.hold.current.pl
If this does not stop the motion of the wheel (e.g., you can hear it spinning or grinding), the last
recourse is to turn off the motor controller itself. Note: any wheels that use near-home type and
are not at home will be lost when the motor controller is powered up again. You should call for
assistance if this happens. To cycle the power on the controller, telnet baytech as motorpow,
password __________[regular flamingos1a password], and then reboot 1, and logout to exit.
b) If the failure was of the limit switch, you need to recenter the mechanism in question, and
redetermine the home point. The best way to do this is to image a very bright star with the telescope
out of focus by about 3000 units. The wheel probably is not well centered, so use one of the tweak
scripts to adjust it (there are special engineering tweak scripts, in addition to the ones for the decker and
MOS wheels). Then step the wheel by discrete positions, and measure the background. With some
help you should be able to determine where you are, and use the ufmotor command <motor_name>o to
rezero the wheel (yes, that is lower-case "o").
c) Because the MOS wheel is operating in relative motion mode (see above), vignetting problems or
rebooting the motor controller with the MOS wheel not at home (imaging position) will require
adjustment with the engineering.tweak.mos.wheel.pl script, NOT by attempting to home the wheel.
Once it is at the imaging position, set the counter to zero with the ufmotor command bo.
FLAMINGOS@2.1-m, Ver. 2.39, 2011 May 13 Page 38 of 46