Epson MX-80 IIIF/T User manual

UV- fo
c

MX-BO
EPSON DOT MATRIX PRINTER
Technical Manual
NORTHAMBER LIMITED
CHEAT OAK HOUSE, ALBANY CLOSL-, ESHER, SURREY. KT109JR Telephofic; Esher (0372) 62071

INTRODUCTION
This technical manual describes the principles of mechanical and
electrical operations, as well as the maintenance and repair pro
cedures, of the EPSON MX-80 Dot Matrix Printer, to permit the user
to understand its functions and thereby to allow the Printer to fully
display its rated performance.
Chapters 3through 5 of the manual deal with the fundemental
troubleshooting, maintenance and repair of the MX-80, and Chapter
6, a simple quick troubleshooting procedure on the basis of a block-
to-block replacement. For details on the disassembly, assembly,
troubleshooting and maintenance of the M-3210 Printer Mechan
ism, refer to the separately published "Technical Manual of EPSON
Model-3210."
'The contents ol this nianuol are subject to change without notice.
SHINSHU SEIKI CO LTD
"All rights reserved."
80 HIROOKA SHIOJIRI-CITY NAGANO JAPAN
REV. A

TABLE OF CONTENTS
CHAPTER 1
GENRAL
1.1 Features of MX-80 1-1
1.2 Features of Interfaces 1-1
1.3 Serviceability 1-1
1.4 General Specifications of MX-80 1-2
1.4.1 Printer 1-2
1.4.2 Parallel Interface (Standard) 1-2
1.5 Major Components 1-3
CHAPTER 2
PRINCIPLES OF OPERATION
2.1 General 2-1
2.2 Block Diagrams 2-1
2.3 Principles of Operation 2-9
2.4 Electrical Circuits 2-9
2.5 Operating Principles of Printer Mechanism 2-23
2.5.1 Head carriage and paper feeding mechanisms 2-23
2.5.2 Print head 2-23
2.5.3 Ribbon feeding mechanism 2-34
2.5.4 Detecting mechanism 2-24
2.5.5 Frame section 2-24
CHAPTER 3
DISASSEMBLY, ASSEMBLY AND TROUBLESHOOTING
3.1 General 3-1
3.2 Tools and Measuring Instruments 3-1
3.3 Disassembly and Assembly 3-3
3.3.1 Removal of Upper Case 3-3
3.3.2 Disassembly of electric ciucuit block 3-5
3.3.3 Disassembly of M-3210 printer mechanism block 3-9
3.4 Symptoms of Trouble and Repair 3-15
3.4.1 General 3-15
3.4.2 Troubleshooting by symptom 3-1 6
3.4.3 Troubleshooting of control circuit board 3-20
CHAPTER 4
MAINTENANCE
4.1 General 4-1
4.2 Lubrication 4-1
4.2.1 Lubricants 4-1
4.2.2 Lubrication standards 4-1
4.2.3 Bonding Standards 4-2
4.3 Adjustments 4-4
4.3.1 Adjustment of head driving pulse width 4-4
4.3.2 Adjustment of timing pulse generating position 4-5
4.3.3 Adjustment of phase relationship
between timing signal and reset signal 4-6
CHAPTER 5
CIRCUIT DIAGRAMS
5.1 GENERAL 5-1
5.2 Connection Diagrams 5-1
5.3 Component Layout Drawings 5-5
CHAPTER 6
ir SIMPLE TROUBLESHOOTING
6.1 General 6-1
6.2 Troubleshooting 6-1
REV. A

$
Fig. 1.1
Fig. 1.2
Fig. 1.3
Fig. 1.4
2.1
2.2
.2.3
. 2.4
. 2.5
. 2.6
.2.7
. 2.8
. 2.9
LIST OF FIGURES
CHAPTER 1
GENERAL
1-3
M-3210 Printer Mechanism
Main and Driver Circuit Boards
1-4
Power Supply Circuit
Upper and Lower Cases
CHAPTER 2
PRINCIPLES OF OPERATION
Flow of Signals
Component Layout of Fuse & Filter Circuit.
Connection Diagram of Fuse & Filter Circuit —
Windings of Transformer
Rectifier and Constant-Voltage Circuit
Flow of Data and Signals through 8155
8155 and Peripheral Circuits
Data Transfer Sequence ^^
Carriage Stepper Motor Drive Signals (Forward)
2-1
2-9
2-9
2-10
2-10
2-12
2-12
2-13
2.10 Paper Feed Stepper Motor Drive Signals.
2-14
2-15
g. 2.11 8041 and Peripheral Circuits
2.1 2 Signal ALE
2.13 8049 and Program Memory Circuits
g. 2.1 4 Locations of DIP Switches
g. 2.15 DIP Switch Status Read Circuit
g. 2.16 Reset (HP Sensor) Circuit 2-18
3. 2.17 Timing (PTS) Sensor Circuit
g. 2.18 Timing and Reset Detection Signals
g. 2.19 Driver Circuit
2.20 Current Waveform of Print Head
2.21 Applied Voltage vs. Driving Pulse Width
2.22 Switches and Indicators on control Panel.
2.23 Switch and Indicator Control Circuit
g. 2.24 Operation of Print Head
2-16
2-17
2-17
2-19
2-19
2-20
2-20
2-21
2-22
2-23
RE

LIST OF FIGURES
CHAPTER 3
DISASSEMBLY, ASSEMBLY AND TROUBLESHOOTING
Fig. 3.1 Removal of Manual Paper Feeding Knob 3-3
Fig. 3.2 Removal of 4 Screws 3-3
Fig. 3.3 Locations of Respective Components 3-4
Fig. 3.4 Dismounting of Driver Circuit Board 3-5
Fig. 3.5 Removal of Control Circuit Board 3-6
Fig. 3.6 Removal of Power Transformer 3-7
Fig. 3.7 Dismounting of Fuse and Filter Circuit Board 3-8
Fig. 3.8 Dismounting of M-3210 Printer Mechanism 3-9
Fig. 3.9 Dismounting of Print Head Unit 3-10
Fig. 3.10 Dismounting of Home Position Sensor Assy 3-10
Fig. 3.11 Unsoldering of Four Lead Wires 3-11
Fig. 3.1 2 Dismounting of PTS Sensor Board Assy 3-11
Fig. 3.13 Dismounting of Timing Belt Motor Assy 3-12
Fig. 3.14 Unsoldering of Lead Wires 3-13
Fig. 3.15 Dismounting of Paper Feeding Motor Assy 3-13
Fig. 3.1 6 Dismounting of PE Board Assy 3-1 4
Fig. 3.17 Normal Waveform of Signal PSEN 3-20
Fig. 3.18 Normal Waveform of Signal ALE 3-20
Fig. 3.19 Normal Waveform of Signal SYNC 3-21
CHAPTER 4
MAINTENANCE
Fig. 4.1 Lube Points and Bonding Points 4-3
Fig. 4.2 Applied Voltage vs. Driving Pulse Width 4-4
Fig. 4.3 Timing Signal PTS (Pin No.39 of 8049) 4-5
Fig. 4.4 Relationship between Timing Signal and Signal PRAV 4-5
Fig. 4.5 Adjustment of PTS Sensor Board 4-6
Fig. 4.6 Relationship between Timing Signal and Reset Signal 4-6
Fig. 4.7 Adjustment of Home Position Sensor Assy 4-7
CHAPTER 5
CIRCUIT DIAGRAMS
Fig. 5.1 Connection Diagram of Control Circuit 5-3
Fig. 5.2 Connection Diagram of Driver Circuit 5-4
Fig. 5.3 Component Layout of Control Circuit 5-5
Fig. 5.4 Component Layout of Driver Circuit 5-6
RFW A

LIST OF TABLES
CHAPTER 2
PRINCIPLES OF OPERATION
Table 2.1 Pin Assignment of ONI 2-2
Table 2.1 Pin Assignment of CN1 (cont.) 2-3
Table 2.2 Pin Assignment of CN2 2-4
Table 2.3 Pin Assignment of CN3
2-5
Table 2.4 Pin Assignment of CN4 2-6
Table 2.5 Pin Assignment of CN5 2-7
Table 2.6 Pin Assignment of CN6 2-8
Table 2.7 Signal Lines from Control Circuit to Control Panel 2-21
CHAPTER 3
DISASSEMBLY. ASSEMBLY AND TROUBLESHOOTING
Table 3.1 List of Tools 3-2
Table 3.2 List of Measuring Instruments 3-2
Table 3.3 Replaceable Circuit Components 3-15
Table 3.4 Replaceable Mechanical Components 3-15
Table 3.5 Major Components on Control Circuit Board 3-20
Table 3.6 3-21
CHAPTER 4
MAINTENANCE
Table 4.1 List of Lube Points 4-1
Table 4.2 List of Bonding Points 4-2
CHAPTER 6
SIMPLE TROUBLESHOOTING
Table 6.1 Replaceable Components in Simple Troubleshooting 6-1
REV. A

CHAPTER 1
GENERAL
CONTENTS
1.1 Features of MX-80 1-1
1.2 Features of Interfaces 1-1
^ 1.3 Serviceability 1-1
1.4 General Specifications of MX-80
1-2
1.4.1 Printer 1-2
1.4.2 Parallel Interface (Standard) 1-2
1.5 Major Components 1-3
RFV. A

1.1 Features of MX-80
1.1 rcaiuic<» w. --
•oi matrix nrinter featuring 80 CPS bi-directional printing with logical
The MX-80 fformation, and is a fruit of our constant
seeking capability and 9 9 dot performance. The Printer is thus
.„„„S ,n pu...« 01
rrr»or.:;rrinr.zT..rir;r^d..,.
MX-80,
1.2 Features of Interfaces
::: L^n^ar" nt:rS::hrMx°8Tcirbe':^
for data communication. th^ My fin has the following interface options which
pef^t'me Ir^cTntct'^ to almost all the computers equipped with various
interfaces.
level prescribed for serial interfaces by the EIA
Printer to receive data at a bit rate ranging from 75 to 9.600 BPS.
H; =h: r=
ated into the computer
(4) TRS-80 Interface
TRS-80 Interface system of a TRS-80 computer manufac-
This optional interface is connected to the bus system oi a i o ^
tured by the Tandy Radio Shack, to permit printing of the TRS-80 programs
data on 'he MX^8a .o^figured to cope with various interfaces. For further
ir.rrr:."r «... ™™.i —
published for each interface.
1.3 Serviceability
The MX-80 has been designed to minimize maintenance and repair in operation under its
Should maintenance or Scents can be
S^reasi?'rcrir;"Lrer,sU" it^ to penorm minimum maintenance and
repair with ease by referring to this manual.
REV. A

1.4 General Specifications of MX-80
1.4.1 Printer
(1) Printing Method Impact dot matrix
(2) Character Set ASCII 96 + Graphic 64 + 9 special
characters/symbols (Selectable by oper
ator)
(3) Character Font 9x9 dot matrix
(4) Character Size 2.1 mm (W) x 3.1 mm (H) (0.08" x
0.12")
(5) Paper Feed Adjustable sprocket feed
(6) Paper Fanfold paper
(7) Paper Width • 101.6 mm (4") - 254 mm (10")
(8) Copies One original plus two carbon copies
(9) Paper Thickness 0.3 mm (0 01") max.
(10) Line Spacing 4.23 mm (1/6"). or programmable
(11) Columns 80 (Normal size)
40 (Enlarged size)
132 (Condensed size)
66 (Condensed-enlarged size)
(12) Print Speed 80 CPS (Normal)
(13) Ribbon Cartridge Ribbon (exclusive use). Black'
(14) Dimensions 374 mm (W) x 305 mm (D) x 107 mm
(H)
(14.7"x I2.0"x 4 2")
(15) MTBF 5 X10'Mines (excluding print head)
(16) Print Head Life 100 x 10" characters
1.4.2 Parallel Interface (Standard)
(1) Date transfer rate 1.000 CPS (max)
(2) Synchronization By externally supplied STROBE pulses.
(3) Handshaking By ACKNLG or BUSY signals
(4) Logic level Input data and all interface control' sig
nals are compatible with the TTL level.
REV. A H2

1.5 Major Components
The MX-80 consists, in a bfoad classification, of the following four major components.
(1) Model 3210 printer mechanism
This mechanism is an assembly of all the mechanical functions of the MX-80, and con
sists mainly of two stepper motors, a print head, a ribbon feeding mechanism, acarriage
assembly, sensors
and a frame section. One stepper motor functions as the print head
carriage
motor, while the other works as the paper feeding motor. The M-3210 has been
designed extremely simple to permit easy maintenance as described later in this
manual.
Fig, 1.1
M-3210 Printer Mechanism
(2) Circuit boards
The MX-80 is provided with two printed circuit boards as the standard equipment. One
printed circuit board functions as a main circuit board (control circuit board) with an LSI
8049 for printer control. On the main circuit board, the other printed circuit board serving
as a driver circuit board is secured with two screws. The M-3210 is controlled through
the 28-pin connector attached to the driver circuit board.
Main Circuit Board
Driver Circuit Board
Fig. 1,2 Main and Driver Circuit Boards

(3) Power supply circuit
The power supply circuit is partially located on the main circuit board. However, the
power transformer and line filter are mounted separately on the lower case. The power
supply circuit supplies all the voltages required for the MX-80. The line filter consisting
of capacitors blocks noises to and from an external source.
Fig. 1.3 Power Supply Circuit
(4) Housing
The housing of the MX-SO consists of an upper case and a lower case, and accommo
dates all the components described mparagraphs (D, (2) and f3) above. The lower case
has been designed to facilitate mounting of the above-mentioned components.
, j, if ^ t
i
'j .A ,1 ' • , rb
Fig. 1.4 Upper and Lower Cases

lati
.1
CHAPTER 2
PRINCIPLFS OF OPERATSON
CONTENTS
2.1 General 2-1
2.2 Block Diagrams 2-1
2.3
Principles of Operation 2-9
2.4 Electrical Circuits 2-9
2.5 Operating Principles of Printer Mechanism 2-23
2.5.1 Head carriage and paper feeding mechanisms 2-23
2.5.2 Print head 2-23
2.5.3 Ribbon feeding mechanism 2-24
2.5.4 Detecting mechanism 2-24
2.5.5 Frame section ....: 2-24
REV. A

2.1 General
This chapter provides the descriptions of signals at the various connectors electrically inter
connecting such major components units as printer mechanism, driver circuit board, control
circuit board and control panel of the EPSON MX-80 Dot Matrix Printer, and explains the
operating principles of the various mechanisms around the electric circuits of the Printer.
2.2 Block Diagrams
The flow of signals through the respective major components ofthe MX-80 is shown in Fio
2.1.
M-3210 Printer Mechanism
CN6 (28-pin.male-type)
iz
CN6 (28-pin, female-type)
Driver ci'cuit board
Control panel
9 leads
CN6
CN4 (22-pm.
male-type)
7\
CN4 (22-pin.
female-type)
(3-pin, male-type) Control circuit board
CN2 (8-pin. male-type)
— — CN3 (26-pin,
female-type)
Transformer
CN5 (22-oin.
male-type)
Iz
CN5 (22-pin.
female-type)
CN1 (36-pln.
female-type)
Power filter
AC 115/220/240V
Fig. 2.1 Flow of Signals
Refer to Tables 2.1 through 2.5 for the pin assignments of respective connectors.
2-1
REV. A

(1) Connector CN1
(a) Use This connector is used for data exchange between the
MX-80 and an external computer (parallel).
(b) Number of pins 36 pins
(c) Part number 57-30360 (AMPHENOL)
(d) Pin assignment Refer to Table 2.1 below.
Table 2.1 Pin Assignment of CN1
Signal
Pin No
Return
Pin No
Signal
Direction Description
1
19
STROBE
In STROBE pulse to read data in Pulse width must be
more than O.S^is at receiving terminal.
The Signal level'S normally "HIGH": read-in of data is
performed at the "LOW" level of this signal
2
20
DATA 1
In
These signals represent information of the 1st to 8lh
bits of parallel data respectively. Each signal is at
"HIGH" level when data is logical "1" and "LOW"
3
21
DATA 2
In
4
22
DATA 3In
when logical "0"
5
23
DATA 4In
6
24
DATA 5In
7 25
DATA 6In
8
26
DATA 7In
9
27
DATA 8
In
10
28
ACKNLG
Out
ApD'Ox 5ms pulse "LOW" indicates that data has
been received and tnat the printer is ready to accept
other data
1 1
29
BUSY
Out
A "HIGH" signal indicates that tne printer cannot re
ceive data The signal becomes "HIGH" in the follow
ing cases
1During data entry
2During printing operation
3 In OFF-LINE State
4During printer error status
-
30
PE
Out A "HIGH" Signal indicates that the printer is out of
paper
13
—
SLCT
Out
This Signal indicates that the printer is in the selected
state
14
AUTO FEED XT
In
With this signal being at "LOW" level, the paper is
automatically fed one line after printing
(The signal level can be fixed to "LOW" with DIP SW
pm 2-3 provided on the control circuit board)
15
- i NC
Not used
16
OV Logic GND level
17 CHASSIS-GND
Printer chassis GND.
In tne printer, the chassis GND and tne logic GND are
isolated from each other '
18
NC
-
Not used.
19 to 30
GND
_TWISTED-PAIR RETURN Signal GND level.
REV. A
2-2

34
Signal ! Return
Pm No ! P'n No
Table 2.1 Pin Assignment of CN1 (cont.)
INIT
GND
SLCT IN
Direction
Not used
Pulled up to -F5V through 4.7 kit resistance
Data entrv to the printer is possible only when the
^vel of tms signal is "LOW" (Internal fixing can be
c'amed oul w'lh DIP SW pm t-8. The cond.Uon at the
time of shipment is set LOW for this Signal.)
Description
When the level of this signal becomes "LOW", the
orintef controller is reset to its initial state and the
print buffer is cleared. This signal "orr^ally at
•HIGH" level, and its pulse width must be more than
SOpiS at the receiving terminal.
The level of this signal becomes "LOW" when the
printer is in —
1 PAPER END state
2OFF-LINE state
3 Error state
•Diiection- refers Z connected at signal ground level.
•Returndenotes TWISTED PA ^ twisted-pair cable for each signal and never fail to
As 10 me s.de To p-e..eoi no.se effect.vely. these cables should be shielded
complete connechon on me e. ^o^nuter and the printer, respectively.
m'e°"acr:oVd.l':ons'are'based on til level Botn Ine rise and tall times of each signal must be less
mr,l.ml?cant'cameT signal or when the
leve' of fie BUSV signal is 'LOW >
2-3
REV.

(2) Connector CN2
(a) Use
(b) Number of pins
(c) Pin assignment
This connector is used to supply the required AC
voltages to the control circuit board.
8 pins
Refer to Table 2.2 below
Table 2.2 Pin Assignment of CN2
Pin No.
Signal Name
Color of Lead
Purpose
1
+12V AC
Gray For
optional interfaces
2-P
12V AC
Gray
3
-f 25V AC
Orange
For stepper motor
4
-1-25V AC
Orange
5+
9V AC
Red
For logic circuitry
6
-I-9V AC
Red
7
-1- lOV AC
Blue
For stepper motor
8-t-
10V AC
Blue
REV. A
2-4

W!)
3
(3) Connector CN3
(a) Use This connector is used when connecting an optional P.O.
board to the MX-80.
(b) Number of pins 26 pins
(c) Pin assignment Refer to Table 2.3 below.
Table 2.3 Pin Assignment of CN3
Connector
Pin No.
Signal Name
Description of Signal
Direction
1
EM
Error
Out
2
PE
Paper End
Out
3
07
Data Bit 7
In
4^ (BUSY)
Ready
Out
5
•6
Data Bit 6In
6
ACK
Acknowledge
Out
7
OS/PAR DIS
Data Bit S/Panty Disable
In
8
MT
Initial
In
9
D4/0/E
Data Bit 4/Odd Parity Select/Even Parity
Select *In
10
Strobe
In
11 D8/SI
Data Bit 8/Serial Signal input
In
12
+ 12
+ 12V AC
Out
13
"R
Reset
Out
14
+ 12
+1 2V AC
Out
15
03/82
Data Bit 3/Bit Rate Select
In
16
+ 5 +
5V DC
Out
17 02/81
Data Bit 2/Bit Rate Select
1
in
18
+ 24
+ 24V DC
Out
19
01/8/7
Data Bit 1/8 Bit Select/7Bit Select
In
20
+ 12
+ 12V DC
Out
21
P/S Parallel Select/Senal Select
In
22
-
t
-
23
SELIN
1 Select In
In
24
GL
[ Ground
-
25
PET TRS
I PET/TRS Select
In
26
GL
i Ground —
NOTE "Direction" refers to tne direction of signal f^ow as viewed from the control circuit board.
2-5
REV. A

(4) Connectors CN4
Two CN4 connectors (one with male contacts and the
other with female contacts) are used to supply control
signals between the control circuit board and driver cir
cuit board of the fv1X-80.
(b) Number of pins 22 pins
(c) Pin assignment Refer to Table 2.4 below.
Table 2.4 Pin Assignment of CN4
Connector
Pin No.
Signal Name
Description of Signal
Direction
-
GP
Ground Level
—
1 2
1' '
GP
Ground Level
—
I 3 i Z., -—
41-—
5
j
GP
Ground Level
—
1 6
GP
Ground Level
—
i 7
{
H8
Head Solenoid Drive Signal
Out
' 8
H7
Head Solenoid Drive Signal
Out
9
H6
Head Solenoid Drive Signal
Out
d.
10
H5
Head Solenoid Drive Signal
Out
11
H4
Head Solenoid Drive Signal
Out
12
H3
Head Solenoid Drive Signal
Out
13
H2
Head Solenoid Drive Signal
Out
-
14
HI
Head Solenoid Drive Signal
Out
tmi
15
H9
Head Solenoid Drive Signal
Out
16
(5550) ;
1-In
17
R I
Reset
In
imi
18
PE 1
Paper End
In
19
ORB !
Phase 8 for Carnage Stepper Motor Drive
Out
tm
20
(132 Columns) i-
Out
21
(FP)
-
Out
22
CRA
Phase A for Carnage Stepper Motor Drive
Out
NOTE; "Direction refers to the direction of signal flow as viewed from the control circuit board.
REV. A
2-6

t9=>
(5) Connectors CN5 connectors (one with male contacts and the
(a' other with female contacts) are use to supply control sig-
nairpetween the control circuit board anddnver circuit
board of tho MX-80.
(b) Number of pms 22
(c) Pin assignment
Connector
Pin No
Table 2.5 Pin Assignment of CN5
Signal Name
CRD
LFB
(80 columns)
Head Trigger
Descriplion of Signal
Pnase D for Carnage Stepper Ivlotor Drive
Phase B for Paper Feed Slepper frtolor Drive
1 Line Feed Activate
Pnase C for narnaqe Stepper Motor Drive
Pnase C for Paper Feed Stepper Motor Drive
Timer Triggering Signal
pnase A tor Paper Feed Stepper Motor Drive
Home Position Signal
pnase D for Paper Feed Stepper Motor Drive
Clock Input
Ground
Ground
+ 24V DC
i + 24V DC
+ 24V DC
-1-24V DC
+ 5V DC
Power Failure Detection Signal
+14V DC
Direction
^ on-.f nnw as viewed from the driver circuit board
NOTE: ••Oirect.on" .efe.s to fne dnection of signa f'ow as viewed
0.7
REV. A