Operating Principles
LQ-300 Service Manual
2.3 CONTROL CIRCUIT
The control circuit consists of the C143 MAIN board assembly. This section
desuibes
the major
components and explains how the board works.
2.3.1 Control Circuit Operation Overview
The printer has a CPU
(TMP90C041)
that runs at 9.8304 MHz, a gate array (E05B02-type), a
PS-RAM
(256K-bit),
a ROM (4 or
8M-bit),
etc. It oversees control of all the components in the
printer. The printer uses the E05B02 gate array to control memory management, parallel
communications, PF motor drive signals, etc. Table 2-8 shows functions of
ICS
and circuits. Figure
2-12 shows the control circuits in
bl&k diagram form.
Table 2-8. Functions of the Main
IC
Ic
I
Location
CPU
I
ICI
+
IC2
EEPROM
IC3
R----R-
Function
Receives data from the host computer and sends it to the input buffer
in RAM (under interrupt processing control). Extends the input data
held in the buffer to create image data. Loads this image data to the
image buffer in RAM. Transfers the image data to the
Printhead
drive circuit. Also controls various parts of the printer mechanism,
such as
PF motor control and color select motor control.
Controls the functions below:
● Input/Output Control
● Memory Management
. Bit Manipulation
● Interface Control
. Expanded Parallel Port
.
Printhead
Control
● Motor Control
An electrically
writable
and erasable ROM used to hold such
information as the TOF position and bidirectional adjustment value.
Driver / receiver
Hardware reset function
Power off detection
Contains the program that runs the CPU and holds the character
design (also called the charaoter generator).
Input buffer
I
1
1
Printhead
Temp.
1
Power Off Sensor
I
Printhead
DRV.
Sensor
I
I
L
I
v
A
<
+35 V Sensor
*
Panel
SWILED
~
Gate Array
4
PE Sensor
1
Parallel l/F
EEPROM RESET
‘
p
”
Y
&kiiEl
4 Release Lever Sensor
D
A
Serial l/F
Color Ribbon Sensor
-.,
f
,.,
.-
.
.
.
Figure 2-12. Control Circuit Block Diagram
2-12
Rev.A
To Next Page
Loading...
