Auto Sheet Feeder (Asf) Unit - Epson Stylus COLOR 900 Service Manual

EPSON Stylus COLOR 900/900N
The functions performed by the pump/ASF motor and switching
mechanism depend on both the direction of motor rotation and whether
the ASF or the pump transmission gear is engaged.
Table 2-4. ASF/Pump Motor Functions
Motor direction ASF gear engaged
• Connecting the
Normal rotation
planetary gear set to
(CW)
the ASF unit
• Reverse rotation of the
paper loading roller (for
returning paper to the
hopper)
• Normal rotation of the
Reverse rotation
loading roller (paper
(CCW)
separation, paper
loading)
The pump/ASF motor specifications are as shown below:
Table 2-5. Pump/ASF Motor Specifications
No. Items
1 Type 4-phase / 48-pole / PM-type stepping motor
2 Drive voltage 42 VDC
3 Coil resistance 7.0
4 Drive mode Bipolar constant current drive mode
Pump gear engaged
• Normal rotation of the
pump (absorption)
• Releases the CR lock
• Extends the wiper
• Connecting the planetary
gear set to the pump
mechanism
• Reverse rotation of the
pump motor
• Locks the CR
• Retracts the wiper
Specifications
±
5% (Applied to the driver)
Ω ±
10%

2.2.4 Auto Sheet Feeder (ASF) Unit

The feed rollers in the ASF unit rotate in reverse before transporting
paper into the printer. As shown below, this lifts the return lever, which
in turn pushes any paper back onto the hopper that may have fallen off
during the previous paper feeding. After this motion is completed, the
feed roller rotates in the normal direction to load paper into the printer.
Figure 2-4. ASF Paper Load Mechanism
The ASF unit includes a sensor to detect the home position of the feed
rollers and to time their change in rotation properly. The sensor's drive
voltage is 5.0 V ± 5% and its output signal specifications are as shown
below:
Table 2-6. ASF Sensor Output Signal
ASF Position
Home position
Out of home position
Chapter 2 Operating Principles
Sensor Output
0.7 VDC or less
2.4 VDC or more
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