System Reset Circuit - Epson LQ-2180 Service Manual

LQ-2180
The following table lists the each function of the main components of
the C272 MAIN board.
Table 2-1. Functions of the Main Board
IC Name Location
CPU IC4
Gate Array IC3
EEPROM IC5
ROM IC10
RAM IC8
CG-ROM IC7
SLA7024M IC11
A2917 IC12
Operating Principles
Function
Detects conditions of various sensors and
controls phase change for the CR motor.
Control the functions below:
• Memory management
• Printhead drive
• Phase change for the PF motor
Contains such information as the factory
setting values for the various adjustments
and the operational record of the printer.
Contains the control program.
Manages the following functions:
• Buffer used to receive data
• Data Extension
• CPU working area
Contains font data.
Constant current drive IC for CR Motor
Constant current drive IC for PF Motor
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2.1.2 System Reset Circuit

The reset IC (IC2) outputs a reset signal under the conditions below to
feed back the status to the CPU and the gate array:
† The printer is turned on or off.
† The voltage level drops due to abnormal condition.
Receiving the signal, the CPU and the gate array immediately shut off
the operation of each IC to prevent the printer from falling into abnormal
status caused by unstable power supply.
P S T 5 9 2 ( I C 2 )
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Control Circuit
C P U ( I C 4 )
1 2 3
V o u t
/ R S T
2
M R E S
V c c 3 G . A ( I C 3 )
7 4
/ R S T
G N D 4
Figure 2-3. Reset Circuit
Revision A
26