Epson Stylus PHOTO 890 Service Manual page 54

EPSON Stylus Photo 890/1280/1290
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ASIC(IC19) detects the motor control current value is 720mA.
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P1 (= number of pulses output during the above carriage movement) is
30* or less.
* Specified value that indicates CR is in the home position. (All edges in the
waveform are used in this condition.)
3) The CR motor rotates backward (counterclockwise) to move the carriage back
to the left, and ASIC(IC19) assumes that the carriage enters the CR lock lever
position when the following conditions are satisfied:
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ASIC(IC19) detects the motor control current value is 500 mA.
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Difference between P1 and P2 (= number of pulses output while the CR
moves from the right frame) is 30 or less.
4) The CR motor rotates backward to move the carriage to the right again, and if
ASIC (IC19) detects the motor control current value is 720 mA, it assumes
that the CR comes in back in contact with the right frame.
5) Difference between P1 and P3 (= number of pulses output for the CR's
movement from the CR lock lever position to the right frame) is 4 or less.
When all the conditions in the sequence are satisfied, the printer detects the CR is in
the home position.
o
PTS (Print Timing Signal) production
The circuit produces PTS signal (cycle: 1/360 inches) by dividing waveform
cycles of Phase A. The print timing signal is used to eject ink at a correct timing.
OPERATING PRINCIPLES
Phase A Phase A
Phase B
Phase B
Figure 2-22. Print Timing Signal and Linear Encoder Phase A
Electrical Circuit Operating Principles
1/180"
1/360"
Revision C
54