OKIDATA OKIMATE 20 User manual

HOWARD W. SAMS &COMPANY CP34 09015
COMPUTERFACTS™
Technical Service Data
OKIDATA®
OKIMATE 20 (MODEL EN3211)
PRINTER
FEATURES COMPLETE SCHEMATICS •PRELIMINARY SERVICE CHECKS •TROUBLESHOOTING TIPS
EASY-READ WAVEFORMS •REPLACEMENT PARTS LISTS •SEMICONDUCTOR CROSS-REFERENCE

SAM§ COMPUTERFACTS' 0K1DATA
MODEL EN3211 OKIMATE 20
PRELIMINARY SERVICE CHECKS
This data provides the user with atime-saving
service tool which is designed for quick isola-
tion and repair of Computer system malfunc-
tions.
e.'i
m
I- o
<,_
QT-
OZ
m
pri
O
o
CO
Ql
O
Check all interconnecting cables for good
connection and correct hook-up before making
service checks.
Always turn Printer Off before connecting or
disconnecting connectors, boards or Computer.
Replacement or repair of the Power Supply,
Driver Board, Interface Board or connectors
may be necessary after the malfunction has
been isolated.
TEST EQUIPMENT
Digital Volt/Ohm Meter
Resistor, 390 Ohms, 1/2W
Resistor, 30 Ohms, 10W
TOOLS
Head Cleaning Equipment (Ethyl Alcohol)
Contact and Switch Cleaner (non-spray type)
Phillips Screwdriver
Flat-Blade Screwdriver
IC Insertion and Removal Tools 28 pin
Low Wattage Soldering Iron
Desoldering Equipment
REPLACEMENT PARTS AND DESCRIPTION
FFuse 2
A
Q1 Transistor (Power Supply Board)
Si
1
Br idge Rect ifier
SW 0n~0ff Switch
LI Coil
R1 Resistor, 5.1 Ohms 3W
M7 Print Head
01 ROM IC
Ml Line Feed Motor
M5 Home Position Sensor
M2 Carriage Motor
SW3 Ribbon End Switch
M4 Paper End Sensor
SAMS Howard W. Sams &Co.
4300 West 62nd Slreef, P.O. Box 7092, Indianapolis, Indiana 46206 U.S.A.
The listing of any available replacement part herein does not
constitute in any case arecommendation, warranty or guaranty
by Howard W. Sams &Co. as to the quality and suitability of
such replacement part. The numbers of these parts have been
compiled from information furnished to Howard W. Sams &Co.
by the manufacturers of the particular type of replacement part
!isted -87CP19021 DATE 11-8?
Reproduction or use, without express permission, of editorial or pic-
torial content, in any manner, is prohibited. No patent liability is
assumed with respect to the use of the information contained herein.
©1987 Howard W. Sams &Co.
4300 West 62nd Street, P.O. Box 7092, Indianapolis, Indiana 46206
U.S.A. Printed in U.S. of America

PRELIMINARY SERVICE CHECKS (Continued)
DISASSEMBLY INSTRUCTIONS
CABINET REMOVAL
Remove ribbon cartridge and carriage assembly
cover. Remove two screws located In front of
Carriage assembly holding cabinet top to
chassis. Push cabinet top toward rear to re-
lease tabs on Inside rear edge and lift up
r&ar. When rear edge is clear of chassis,
move top forward to clear front tabs and lift
top from Printer.
PRINTER MECHANISM REMOVAL
Remove Control Panel
Connectors CN4 thru CN8. cover
.
Dl sconnect
NOTE: Lift up cap on Connector CN6 before
pulling flat ribbon cable out.
Remove three screws holding mechanism to
cabinet bottom.
POWER SUPPLY AND DRIVER BOARD REMOVAL
Remove cabinet top and Printer mechanism.
Remove two screws holding Power Supply Board
to cabinet bottom. Push back tabs holding
front of Driver Board and lift Driver and
Power Supply Boards from cabinet.
CARRIAGE MOTOR ASSEMBLY REMOVAL
Remove cabinet top. Disconnect Connector CN6
from Driver Board. Remove two screws holding
motor assembly and remove assembly.
PAPER FEED MOTOR REMOVAL
Remove Printer mechanism. Disconnect Connec-
tor CN8 from Driver Board. Remove two screws
holding Paper Feed Motor and remove Motor.
BELT REMOVAL
Remove cabinet top and Control Pane! cover.
Remove Carriage Motor assembly. Remove two
springs from metal linkage going from Head
Hold Solenoid to left belt gear (one spring at
each end of the link). Insert aflat-blade
screwdriver between left belt gear and metal
link. Pry link and ribbon stop lever off gear
post, note position of ribbon stop lever for
reassembly. Remove belt from Print Head assem-
bly and gear pul leys.
RIBBON REMOVAL
Turn Power Off. Lift ribbon access cover.
Pull back on Print Head assembly until It
snaps back. Lift used ribbon cartridge out.
Place new cartridge Into compartment, rear end
first. While lowering front end, make sure
ribbon Is In front of Print Head and behind
ribbon guides. Snap head back into printing
pos 111on
.
REPLACING PRINT HEAD
Remove ribbon cartridge. Pull back on Print
Head Lock Lever, directly behind Print Head.
Lift Print Head straight up out of holder.
m
(5D
17 CN3 M7 CN6 M4
(7C)
Jb)@ ®@® ^©@ GEAR
ASSEMBLY
6A)
CHASSIS-OVERALL VIEV

SERVICE CHECKS
MATCH THE NUMBERS ON THE INTERCONNECTING DIAGRAM AND PHOTOS WITH
THE NUMBERS ON THE SERVICE CHECKS TO BE PERFORMED.
PRINTER DEAD
(A) Check Fuse Fon Power Supply Board.
If open, check for possible shorts
at Diode S11and Oscillator Transis-
tor (Ql)«
(B) If Fuse Fis good, apply power and
check for 167V at the cathode of
Diode Sit. if 167V is missing,
check On-Off Switch (SW), Coil LI,
Resistor R1 and Diode Sil.
(C) If !67V is present at Diode Sil,
check for 14.4V at pin 1of Connec-
tor CN9 on Driver Board. If reading
is not correct, check adjustment of
Voltage Adjust Control CVR).
(D) If 14.4V is missing at pin 1of Con-
nector CN9, turn Power Off, discon-
nect Connector CN9 and connect a390
Ohms resistor from pin 3to pin 4
and a30 Ohms 10W ioad from pin 1to
pin 6of Connector CN on Power Sup-
ply. Apply power and recheck Power
Supply output voltages. if voltages
are still missing, troubleshoot
Power Supply Board. If voltages re-
turn, troubleshoot Driver and Inter-
face Boards.
(C) Check ROM IC (Q1 )by substitution.
(D PRINT HEAD WILL NOT PRINT
(A) Check Print Head (M7) connections
and Connector CN6. Check Print Head
Ribbon Cable.
(B) Examine element points on Print
Head. If elements appear dirty,
clean Head with asoft cloth dampen-
ed with ethyl alcohol. If elements
appear white, substitute Print Head.
(5) MISSING DOTS IN THE PRINT PATTERN
(A) Clean Print Head face with asoft
cloth dampened with ethyl alcohol.
CB) Check Print Head connections
Connectors CN3 and CN6. and
(T) PRINTER WILL NOT PRINT BY COMPUTER COMMAND
(A) Check Connector CN2 on Interface
Board.
(B) Check settings of DIP Switches SW1
and SW2 on Interface Board. See
"Switch Settings" for alist of the
various settings.
(?) PRINTER CARRIAGE ASSEMBLY
Q
(A) Carriage asembly does not move.
Check carriage assembly belt, gears
and pu Ileys.
(B) Check Connectors CN3, CN5, CN7 and
CN9.
(C) Check Carriage Motor (M2) windings
for continuity. Check for 14 Ohms
from pin 1to pin 5, pin 3to pin 5,
pin 2to pin 6and pin 4to pin 6of
Connector CN7.
(D) Carriage assembly moves to right
only and stops. Check operation of
Home Position Sensor. Check for
4.5V at pin 8of Connector CN5 when
Print Head is at Home Position and
0V when Head is not at Home Postion.
If readings are not correct, check
pins 6, 7and 8of Connector CN5 and
the Home Position Sensor (M5).
LINE FEED WILL NOT OPERATE
(A) Check Line Feed gear assembly on
right side of platen.
(B) Check Connector CN8.
(C) Check windings of Line Feed Motor
(Ml) for continuity. Check for 7
Ohms from pin 1to pin 5, pin 3to
pin 5, pin 2to pin 6and pin 4to
pin 6of Connector CN8.
READY LED BLINKS
(A) Ready LED blinks, pressing Select
Switch has no effect. Check pins 1
thru 5of Connector CN5.
(Bi Turn Printer Off. Check operation
of Ribbon End Switch (SW3) with an
ohmmeter at pins 1and 2of Connector
CN5. The reading should be zero
ohms with Switch activated and
infinity with Switch not activated.
(C) Turn Printer On and check operation
of the Paper End Sensor (M4). Check
for 5.0V at pin 1of Connector CN5
with paper in Printer and 0V with no
paper.
NOTE: The Ribbon End Switch must
not be activated.
If readings are not correct, check
Paper End Sensor (M4).

PRELIMINARY SERVICE CHECKS (Continued)
POWER SUPPLY BOARD
@Q1
@.
®
SW2
8W1
CN2 x
INTERFACE BOARD
IV