Paxar 656 / 636 - Manual (Page 38)

32 • Maintenance / Adjustments Users Manual Model 656/636
Print Head Adjustment
Tangent
Proper print head tangent is perhaps the most important adjustment to make. A
printhead which is not properly adjusted will result in poor print quality, poor heat
dissipation and possible ink wrinkling problems. When the machine was
manufactured, the print head was adjusted to the proper tangent point on the platen
roller, however, with print head replacements the tangent point for the new print
head may change. It is necessary to understand how to properly adjust the printhead.
Clean Platen Roller
You may determine if the printhead has been adjusted properly by performing a test
pattern as documented elsewhere in this manual. A properly adjusted print head will
produce an even grid of chevrons when the test pattern is performed. Before
making any judgments as to the quality of the printhead, it is absolutely
necessary to ensure that the platen roller and the printhead is clean of all
debris. Clean the platen roller located immediately beneath the print head with a
clean cloth and a small amount of alcohol. Be careful not to damage the platen roller
while cleaning. If the roller is worn, replace the roller.
Print Head Pressure Setting
The print head pressure setting is very important. Keep the lightest setting possible.
This will improve print head life while maintaining quality print.
The printer has been factory set. Further adjustment of pressure adjusting screw
should be minimal.
If readjustment is required, proceed as follows: Power on the printer. Remove the
ink and card stock from the printer. With the print head open, turn the pressure
screw counterclockwise until it does not contact the printhead mount plate, it should
slide freely back and forth. Close the print head. Slide the pressure screw until it sits
directly over the center of the web. Turn the pressure screw clockwise until it makes
contact with the head mount plate plus 1/2 turn to add pressure. As the web width
changes adjust the pressure screw accordingly.
Download the proper format for the stock that is loaded. Press start. The print quality
should be acceptable if the pressure screw is properly positioned.
Once the print quality is acceptable, start to back off the screw until the print begins
to fail. Once the print is starting to fail, increase the pressure by 4 clicks. Minimum
pressure should be used when running narrow webs, wide webs require slightly
greater pressure. Additional print quality will be obtained by adjustments of the
Tangent point, (see Print Head Tangent Point)
If you are unable to correctly adjust the screw for good print, call for service.