Control Circuit Operation; Control Circuit Operation Overview - Epson LQ-870 Service Manual

2.3 CONTROL CIRCUIT OPERATION

The control circuit consists of three boards: the main board (CO60 MAIN, CO61 MAIN, or CO69 MAIN B), which is the
main control board, the CO60 DRV board, the driver board (used only with the CO60 MAIN board), and the CO60 PNL
board, the control panel board. The CO61 and CO60 MAIN B boards combine main control circuitry and driver circuitry
on one board. This section describes how these boards work.

2.3.1 Control Circuit Operation Overview

The printer's CPU is an 6-bii CPU TMP9OCO41 that runs at 10 MHz. It controls all the components of the printer. The
rationalizes and simplifies the circuitry and contains all the driver circuits for driving the printer mechanism on five chips.
Figure 2-17 shows the control circuits in block diagram form.
CO60 PNL
Control
Panel
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..-.-..-~...-..--.........~~-.?..........~~~.-.-...~....~...~--.............
Parallel
Optional
. . . . . .._...__..
Gate array
GAP Platen-gap adjust lever position sensor
HP Home-position sensor
RELEASE Release sensor
Front paper-out detector (positioned in front of the printer mechanism)
PE2
Rear paper-out detector (positioned behind the printer mechanism)
various
memory management functions that assign memory
Figure 2-17. Control Circuit Block Diagram
CO60 MAIN CO61 MAIN CO60 MAIN B
EEPROM
MASK
PROM
ROM
512K
8M
i SLA7024M
i (1~7)
i
2-14
and
PSRAM