Epson Stylus Pro 7400, Service Manual

Page: 154 / 428

EPSON Stylus Pro 7400/7800/9400/9800 Revision B
Operating Principles Print Mechanism Components 154
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PG HP Sensor (Platen Gap HP Detection)
A shield is attached on the shaft of the PG slide gear (on the carriage) which works
with the pump motor. The sensor detects the edge of the shield to adjust height of
the print head.
It is shaped like a cam to realize five head positions relative to the mechanical
home position.
NOTE: Error number displayed when the total pulse count has exceeded 1000:
0001000C PG origin detection error (Service Call Error)
Figure 2-4. Head Slide (PG Change) Initialization Sequence
Table 2-4. Pulse Positions
Position
Gap
Width
Application
Pulse Count from Origin
(Converted to 2-2 Phase Excitation)
Maximum 2.6mm For thick paper 193
Large 2.1mm For paper which can be soiled
if setting is for thin paper 409
Medium 1.6mm For particular thin paper
which can be easily scratched 625
Small 1.2mm For thin paper 841
Minimum 0.8mm For film type media 1057
One round --- --- 1080
Pump motor runs forward until PG_HP sensor turns
OFF
Sensor is OFF?
Start
Pump motor runs forward until PG_HP sensor turns ON
Yes
No
Yes
No
No
Yes
Sensor is OFF?
Sensor is ON?
Pump motor runs forward until PG_HP sensor turns
OFF
No
Sensor is OFF?
Yes
Pump motor runs forward by 841 pulses
(to the “small PG” position)
Pump motor runs forward by 48 pulses
(to release the epicyclic gear)
End
Sequence for moving to pseudo-vacuum position
Pump motor runs forward by 15 pulses
after PG_HP sensor turns ON