Platen Gap Adjustment - Epson LQ-670 Service Manual

Chapter 2 Operating Principles

2.1.5 Platen Gap Adjustment

Platen gap (the gap between platen surface and print head) allows the printer to use different thickness of
paper by setting appropriate gap so that the different thickness of paper can avoid getting printing dirt or
picking the ribbon accidentally. Adjustment mechanism consists of the CR guide shaft, parallelism
adjustment bush, adjust lever and PG detector.
The rotating center of the CR guide shaft is angled to the rotating center of the adjust lever. Rotating the
adjust lever enables the print head to get closer to or away from the platen surface. The parallelism
adjustment bush should set the CR guide shaft parallel to the platen surface. The PG detector detects the
position of the adjust lever and changes the printing speed to the copy mode when using the thick paper
and setting the adjust lever more than 2 levels.
Type
Switch Rating
Switch Mode
2-10
Figure 2-7. Platen Gap Adjustment Mechanism
Table 2-10. PG Detector Specification
Category Specification
Mechanism Type
0.6 1.0mA, 5VDC 5%
Normal Mode : Open
Copy Mode : Short (more than 2 levels)
Rev. A