REV.-A
Table 2-5. Functions of the Main IC and Circuits
or Circuit
Location
Functions
1 2 C
Receives data from the host computer and loads the data to the input buffer in
RAM (under interrupt processing control). Expands 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 the motors.
4 B
This gate array consists of seventeen components configured on a single chip:
Memory Management Unit
Wait Control Unit
Refresh Control Unit
Program ROM Select Unit
Centronics I/F Control Unit
Option Control Unit
Panel Control Unit
EEPROM Control Unit
General Output Unit
HPW Differential Unit
HPW Pulse Limit Unit
Bit manipulation unit
Head Control Unit
Internal Clock Generate Unit
Internal I/O and
Decode Unit
PROM
3A
RAM
4A
5 A
MROM
( M a s k R O M ) 2 A
EEPROM
5 c
V r e f C i r c u i t
TL43 1
Output Data Multiplex and input Data Latch Unit
This is a drive circuit for the printhead. It consists of six chips.
The PROM contains the program that runs the CPU.
The RAM contains the CPU working area and the various buffers. (5A is not used
and not installed in the
printer.)
The mask ROM contains the character design (also called the character
generator).
The EEPROM is an electronically
and erasable ROM that contains infor-
mation such as the top-of-form position.
This circuit generates the reference voltage used irrthe A/D converter in the CPU.
2-16
Summary of Contents for LQ-1170
Page 1: ...LQ 1170 24 PIN DOT MATRIX PRINTERS TM LQ8 1170 ...
Page 2: ...L Q 8 7 0 1 1 7 0 SERVICE MANUAL EPSON T Printed on recycled paper ...
Page 101: ...10 9 91 Yes NO Replace pluggable chips on main board 5 6 ...
Page 110: ...Table 5 4 Repair of the Power Supply Board Continued 5 15 ...
Page 118: ......
Page 121: ...REV A Figure 6 2 LQ 870 Lubrication Points 6 3 ...
Page 122: ...REV A Figure 6 3 LQ 1170 Lubrication Points 6 4 ...
Page 134: ...1 I II ...
Page 135: ...REV A Q m u D w IL 0 1 xl Figure A 3 CO60 DRV Board Circuit Diagram A 11 ...
Page 136: ...Figure A 4 CO60 PSB Board Circuit Diagram A 12 ...
Page 138: ...LO SLOE002 OWO9 1Nd 0 9 0 3 5 f l P I 11 I 01 I 6 I 8 1 L 9 I 9 I B I I2 I 2 I 1 ...
Page 142: ...REV A Fl 24ov T3 IsA I I II II AL I CU rl Figure A 10 C060 PSE Board Component Layout A 1 8 ...
Page 143: ...LMS d10 IP IMS dla ...
Page 144: ...REV A A 4 EXPLODED DIAGRAM Figure A l 2 1 Exploded Diagram for LQ 870 A 2 0 ...
Page 145: ......
Page 146: ...REV A Figure A 13 1 Exploded Diagram for Model 5DlO A 22 ...
Page 147: ... 5 2 5 610 c 3 5 9 0 El ...
Page 149: ...REV A A 5 CASE OUTLINE DRAWING Figure A l 4 1 Case Outline Drawing for LQ 870 A 25 ...
Page 151: ...lllllll IllI l l IIIIII II0 IIll III1 I I I C O 6 1 M A I N B o a r d A 3 7 ...
Page 152: ... U nRonenl2 i i C O 6 0 HAIN B t _1 m r OL J IIA IS I 19 CNI 36 I I8 I 23 IS ...
Page 153: ...a i iJ 0 E fig tfti I z ...