Epson Stylus Pro 7400 Service Manual page 154

EPSON Stylus Pro 7400/7800/9400/9800
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)
Table 2-4. Pulse Positions
Gap
Position Application
Width
Maximum 2.6mm For thick paper
Large 2.1mm For paper which can be soiled
if setting is for thin paper
Medium 1.6mm For particular thin paper
which can be easily scratched
Small 1.2mm For thin paper
Minimum 0.8mm For film type media
One round --- ---
Operating Principles
Pulse Count from Origin
(Converted to 2-2 Phase Excitation)
193
409
625
841
1057
1080
Print Mechanism Components
Start
Sequence for moving to pseudo-vacuum position
Sensor is OFF?
No
Pump motor runs forward until PG_HP sensor turns
OFF
No
Sensor is OFF?
Yes
Pump motor runs forward until PG_HP sensor turns ON
No
Sensor is ON?
Yes
Pump motor runs forward by 15 pulses
after PG_HP sensor turns 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
Figure 2-4. Head Slide (PG Change) Initialization Sequence
Revision B
Yes
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