Service Checks; Auto Gap Service Check - Lexmark 4227 - Forms Printer B/W Dot-matrix Service Manual

4227-300

Service checks

Auto Gap service check

Theory of operation
The Auto Gap motor and Gap Home sensor automatically set the
printhead gap for the thickness of paper being used by rotating the
eccentric carrier shaft. The printer detects maximum gap with the
Gap Home sensor, and minimum gap by driving the printhead
against the platen. In addition to compensating for the thickness of
the paper itself, the printer must increase the air gap for thicker
papers.
With Auto Gap On, the following occurs:
•
POST
•
Auto Gap resets.
•
The printer unloads paper, if it is loaded, to prepare to measure
the travel span.
•
The Auto Gap motor drives the printhead against the platen to
measure the total travel span.
•
Auto Gap resets again, to make room for paper to be loaded.
•
The paper feeds to the print line.
•
The Auto Gap motor drives the printhead against the paper to
measure the total travel span minus the paper thickness.
•
Auto Gap resets again.
•
The printhead moves to the appropriate gap position for the
installed paper.
•
The Ready LED comes on, the carrier centers, and the paper
moves to the tearoff position.
Diagnostic information
2-11