Service manual
REV.-A
2.3 Control Circuit Operation
The control circuit consists of two circuit boards: the
C094
MAIN (the main control circuit board) and the
C094
PNL (the control panel circuit board). This section describes the operation of these boards.
2.3.1 Control Circuit Operation Overview
The CPU on the C094 MAIN is the 8-bit TM
P90C041F
microprocessor (9.83 MHz). It oversees control of all the
components of the printer. The E05A66YA gate array contains various memory management functions that
control the memory assignment and
1/0
areas. The output signals from each detector are sent to the analog
input
poti
of the CPU. The signals from the control panel are sent to the gate array, which in turn sends LED
signals to the control panel. The two motors (CR and PF) are controlled by signals sent from the stepping
motor control port of the CPU. Figure 2-23 shows the control circuits in block diagram form.
7
ETROM
4K
BIT
Ic
5C1
I
1-
)
7
1
.
n
-
1
CONTROL
b
PANEL
BUITONS
AND LEDS
PG
PE FRONT
.
m
PE REAR
RELEASE
SENSOR
SENSOR
SENSOR
LEVER
SENSOR
.
—
h-
1
CR
HOME
SENSOR
WE-1
D
HEAD
THER-
MISTOR
~
+5vDc
m
Data bus
~
+35vDc
k-~
Addrt?ss
bus
Figure 2-23. Control Circuit Block Diagram
2-22