Epson LX-300 Service Manual

Operating Principles
LX-3(M Service Manual
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- 140) on the system IC (ICI) are used to control the stepping motor. The pulse
signal
from the IC1 controls four transistors and the stepping motor. l%e motor is driven at fiv
e
speeds, 800, 900, 1000, 1200, and 1300 pps, to correspond to the idling voltage and the paper
handling condition. The ICI controls motor speed. At the holding time, The pFCOM voltage is
chang4-VP into VL
via A4 by the IC1. “
SYSTEM IC (ICI)
MOTOR ASSY.,PI
(
R84 Q11
PFA
-
’
37
PF~
13s
R86
PFA
Q1
PFA
PB- ‘3
Ra5 Q13
Pm
R87
Q14
Pm
PFB
‘“O
nm7
I
‘1
*
‘L
VP
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.
Printhead
SYSTEM IC (ICI)
I 1 ‘~
HD1
HD2
HD3
HD4
HDs
HD6
HD7
HDs
HD9
F14
;p~~
At&
68
RIO
D1
~
-c?
Rll
Figure 2-19. Printhead Driver Circuit Diagram
( {“ ‘:
( <<-:
2-16
Rev.A

Epson LX-300 Specifications

General

Print Method	9-pin impact dot matrix
Interface	Parallel
Paper Handling	Friction feed, tractor feed
Weight	4.4 kg
Operating Environment	Temperature: 5 - 35°C, Humidity: 10 - 80%