Paxar 656 / 636 - Manual (Page 39)

Users Manual Model 656/636 Maintenance / Adjustments • 33
Squaring the Print Head
If the test pattern, printed on a wide web (4" (100mm) plus), is lighter on one edge
than the other, it is possible that the printhead is out of square. This can be detected
by looking at the front edge of the print head in reference to the printhead holder.
To remedy this problem, power off the machine and remove the print head as
outlined in the print head installation information. The printhead adjustment plate
has been manufactured so when properly adjusted the head will be square. The
printhead holder has a locator plate that must be slide up snug against the printhead
mount plate. Install the head and it should be square to the web.
Print Head Tangent Point
The print head pressure adjustment must be done with the head pressure set light.
Turn the pressure screw counterclockwise. Run a test pattern to determine the
adjustment required.
If the entire test pattern is broken up, the printhead is probably not adjusted to the
proper tangent point. To adjust the tangent point loosen the two print head lock
screws one half turn with a 2.5mm ball driver provided in your spare parts kit. Do
not remove the print head from the printer.
Once the screws have been loosened, use the adjustment thumb screw to move the
head forward and backwards. Since the adjustment is very precise, do not turn the
thumb screw more than 1/4 of a turn before running another test pattern to determine
if you are adjusting the print head in the proper direction. Tighten the two mount
screws (Do not over tighten). Run a test pattern again to determine further
adjustment required.
Once you have restored a smooth even test pattern, re-tighten the two print head
mount screws (Do not over tighten) and run one last test pattern.
Registration Sensor Adjustment
Adjusting Print Sensor Position
If you are running sense mark material with a hole or slot for registration:
- Open the feed roller and print head.
- Move the stock by hand in the feed direction until the registration desired is in the
slot window for the pickup sensor.
- Close both the feed and print head.
- Slide the top sensor assembly using the sensor handle while looking at the
registration index sensor. When the light turns on, and stays on, the sensor is over
the registration hole.
If your machine stops, for no apparent reason, while it is in the middle of printing a
batch of tickets, you may be missing sense marks (three consecutive tickets in which
a sense mark was not found). Check for the following:
- The front panel will display a screen indicating that there has been a missed
sensor error.