EdgeGroove3244.spt is used to determine the best drum position for the plate edge detect sequence. This script is suppleid by the Thermal 2 group.

The 3244 version requires a plate to be loaded and assumes the host controller is an MPE.

The problem in the 3244 application is that the edge detect groove is so close to the leading edge clamp that there is no way to get a leading side signal from which to derive the best edge detect drum position. By doing the second pass over plate we can observe where the leading edge limit is.

• The first pass is done at a carriage position where there must be no plate. The focus lens is contracted, for earliest exit of the focus beam from the edge detect groove.
• The second pass is done at a carriage position where there must be a plate. The focus lens is extented for latest clearing of the clamps. The scripts asks for the carriage positions. Note that one cannot do an edge detect to know, because it doesn't work yet.

To create the worst case conditions, the focus laser transmitter is turned on at full power and the focus receiver is at full gain for the edge detect groove pass. Thus the focus SUM signal will rise to saturation as fast as possible. The on-plate pass is done at nominal settings for the active media.

The resulting graphs represent the limit possible for a given head install on a given machine. Select the operating drum position for edge detect in the middle of the O.K. area.

IMPORTANT NOTE: The off plate carriage position must be selected so that the focus beam end up over one of the wide grooves for the clamp bands, since the edge detect drum position must take into account the case where the plate edge is over one of these grooves. The default off plate carriage position should put you over one of these grooves. This requirement reduces the margin for the drum position significantly.

In the example graphs below, one was done properly, and one was done without the focus beam over a clamp band groove.

IMPORTANT NOTE: There is somewhat of a problem in the case of the 3244 engine in that there is not a single EPOS that will satisfy all the possible conditions at once. See the third Graph below, where the on plate part of the graph was done at the operating point for the media (NOTE: The script has been modified to do this now also), preventing widening of the results due to finite focus beam width (it was also done at higher resolution).

When to run this script: Anytime a TH2 head is installed, or its mounting is adjusted, on a 3244 engine. Or, if you ever have troubles with image shifting in the subscan direction and towards the home position.

Instructions:

1. Mount a plate.
2. Run the script.
3. Enter the best drum EPOS. For example:
   

   >> set drum epos
   NVS drum subsystem:
   edge_position = 425  Saved = 425  Default = 450   tach ticks
   Range: 0 to 36000
   >> set drum epos 402
   NVS drum subsystem:
   edge_position = 402  Saved = 425  Default = 450   tach ticks
   >> nvs save drum epos
   Saving drum edge_position