Paper Feed Motordrivecircuit; Printhead Drive Circuit - Epson LX-300 Service Manual

Operating Principles
2.3.7 Paper Feed Motor Driver Circuit
Figure 2-18 shows the paper feed motor driver circuit, an open-100P, constant-voltage drive with
1-2 phase excitation.
The ports (pins 137- on the system IC (ICI) are used to control the stepping motor. The pulse
140)
signal
from the
speeds, 800, 900, 1000, 1200, and 1300 pps, to correspond to the idling voltage and the paper
A4 by the IC1. "
via
SYSTEM IC (ICI)
Figure 2-18. Paper Feed Motor Driver Circuit Diagram
2.3.8 Printhead Driver Circuit
Figure 2-19 shows the printhead driver arcuit block diagram. Print data, already expanded into
image data, is split by the CPU block and transferred to the latch arcuit in the gate array block in
the system IC (ICI). Port AN6 (pin 66) of ICI samples the voltage of the +35 VDC line via the A/D
converter. By sampling the +35 VDC line voltage and dete rmining the length of the head drive
signal, it is possible to maintain the energy supplied to the head at a constant level. If the voltage
from the +35V line is HIGH, ICI shortens the output pulse. If the voltage from the +35 VDC line is
LOW, ICI lengthens the output pulse.
SYSTEM IC (ICI)
I
Figure 2-19. Printhead Driver Circuit Diagram
2-16
Q 1 1
- 3 7
PFA '
13s
Q 1 3
I
R
IO
D1
- c ?
R l l
MOTOR ASSY.,PI
' L
VP
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