Subject: DIS turrett detent problem solved

From: Jon Brinkmann

Submitted: Mon, 28 Jul 1997 17:39:09 -0600 (MDT)

Message number: 37 (previous: 36, next: 38 up: Index)

Mike Carr, Richard Lucinio, Charles Corson and myself solved a
long-standing DIS problem two weeks ago.  The problem was that the
"dis home" MC command leaves the detent retracted, so the turret is not
locked in place.  This produces random errors in the low-res spectra,
since the low-res position is the home position.

The problem existed due to a code change made several years ago in the
Mirella code on the DIS PC, in which an extra command was added to home
the detent after the turret was homed.  This "DHOME" command retracts
the turret.  I deleted the command from the source file, with the
result that the detent now functions properly.

We also checked the mechanical integrity of the turret wheel assembly.
No mechanical problems were found.

We have performed several tests of the turret registration (take a
spectra, change the configuration, return to the original configuration
and take another spectra) in the past two weeks.  We see variations on
the order of one pixel, which while not optimal, are much better than
previously reported.

Jon Brinkmann
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