Operating Principles
LX-300 Service Manual
2.3 CONTROL CIRCUIT
The
control circuit consists of the
C130
MAIN board
assembly.
This
-on
describes
the major
(
:
“
components and explains how the board works.
2.3.1 Control Circuit Operation Overview
The printer’s system
IC
contains a CPU
(pPD78C10A-type)
that
mm at
14.74
MHz, a gate array
(E05A79-type) and a main RAM ( 8KB
SRAM).
It oversees
control
of
all
the
components in the
printer. The printer uses the E05A90 gate array to control address
decodins parallel
communidion.s,
PF
motor drive signals, etc.
Table
2-5 shows
functions
of main
IC
and
arcuits.
Figure 2-18 shows the control circuits in block diagram form.
Table 2-8. Functions of the Main
IC
Ic
Location
Function
CPU Block: 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
SYSTEM
IC
ICI
Gate Array Block: Controls the functions below.
w
Address decoding
. Parallel communications
●
Impact
head drive control
. CR motor control
Main RAM Block: Holds the CPU
worldng
area and various buffers.
ROM
El
Contains the program that runs the CPU and holds the character
design (also called the character generator).
RESET
IC
A2
Hardware reset function
EEPROM
A3
An electrically writable and erasable ROM used to hold such
information as the TOF
pos
it-km
and bidirectional adjustment value.
Serial l/F
IC
IC2 Driver / receiver
_&m
1+
SYSTEM
IC
RESET
IC
*
(lCl)
4
(AZ)
.~w
.h#Jwfax4usY#J
PROM
.mww
RELEASE
(El)
Ai
LEVER
~:
SENSOR
::
+5V
OC(VL)
:
(OPTION)
!
. . . . . . . . . . . . . . . . . . .
Figure 2-12. Control Circuit
Block Diagram
(~
“
..-.
/
r
.,,
,
--
,.
2-12
Rev.A
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