OKIDATA ML320 Turbo User manual

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Page: 1
Service Guide ML320/321Turbo
Chapter 0 About This Manual
ML320 Turbo // ML321 Turbo
Dot Matrix Printers
Adobe Acrobat printable reference
copy of the OKIDATA Service Training Manual.
09/17/97
Note: This Adobe Acrobat version of the Okidata Service Training Manual was built with the
pictures rendered at 300 dpi, which is ideal for printing, but does not view on most
displays well.
Okidata is a registered trademark, and OkiPage is a trademark of Oki Electric Industry Co., Ltd. HP,
LaserJet and PCL5e are trademarks of Hewlett-Packard Co. Adobe and Acrobat are trademarks of Adobe
Systems Incorporated.
Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business
Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

Table of Contents Page
Service Guide ML320/321Turbo
0 About This Manual
Front Cover 1
1 Configuration
1.1. Standard Printer Configuration 2
1.2 Options 3
2 Operation Description
....2.1.1 Summary 4
....2.1.2 Microprocessor and the Peripheral Circuit 5
....2.1.3 Initialization 6
....2.1.4 Parallel Interface Control 7
....2.1.5 Print Control 8
....2.1.6 SP/LF Motor Control 9
....2.1.7 Operation Panel 10
....2.1.8 Alarm Circuit 11
....2.1.9 Power Supply Circuit 12
2.2 Mechanical Operation 13
....2.2.2 Spacing Operation (See Figure 2-4.) 14
....2.2.3 Head Gap Adjusting (See Figure 2-5.) 15
....2.2.4 Ribbon Drive (See Figure 2-6.) 16
....2.2.5 Paper Feed Operation 17
....2.2.6 Paper Detection Mechanism (See Figure 2-15.) 18
....2.2.7 Automatic Sheet Feed 19
....2.2.8 Paper Park Function (Continuous sheet paper) 20
3 Parts Replacement
3. ASSEMBLY/DISASSEMBLY 21
3.1 Precautions for Parts Replacement 22
3.2 Service Tools 23
3.3 Disassembly/Reassembly Procedure 24
....3.3.1 Printhead 25
....3.3.2 Ribbon Protector 26
....3.3.3 Pull-up Roller Assy 27
....3.3.4 Upper Cover, Access and Sheet Guide Assy 28
....3.3.5 Gear Case Assy 29
....3.3.6 PC Connector 30
....3.3.7 Space Motor, Guide Roller Assy 31
....3.3.8 Space Rack 32
....3.3.9 Carriage Cable 33
....3.3.10 Backup Roller Holder Assy 34
....3.3.11 Platen Assy 35
....3.3.12 Driver Board (SDDV) 36
....3.3.13 LF Motor 37
....3.3.14 Operation Panel PCB (LEOP) 38

Table of Contents Page
....3.3.15 Control/Power Supply Board (SDCT) 39
....3.3.16 Transformer Assy 40
....3.3.17 Change Lever and Gears 41
....3.3.18 Carriage Shaft 42
....3.3.19 Paper Pan 43
....3.3.20 Rear Tractor Assy 44
....3.3.21 Rear Pressure Assy 45
....3.3.22 Switch Lever 46
4 Adjustments
4. ADJUSTMENT 47
5 Periodical Maintenance
5.1 Cleaning 48
5.2 Lubrication 49
6 Troubleshooting
6.1 Items to Check Before Repair 50
6.2 Troubleshooting Table 51
6.3 Lamp Display 52
6.4 Connection Circuit Check for Printhead and SP/LF Motor 53
6.5 Troubleshooting Flow Chart 54
A Centronics Parallel Interface
A. PCB LAYOUT 55
B Parts Listing
Parts Listing 56
Figure 11-1 Upper Cover Assy 57
Figure 11-2 Printer General Assy 58
Figure 11-3 Printer Unit 59
Figure 11-4 Carriage Assy 60
Figure 11-5 Option Spare Parts 61
C Software Diagnostics and Adjustments
RS-232C SERIAL INTERFACE BOARD 62
2. OPERATION DESCRIPTION 63
....2.2.1 Operation at power on 64
....2.2.2. RS-232C interface 65
2.3 Communication Procedure Flowchart 66
3. TROUBLESHOOTING FLOWCHART 67
3.3 Local Test 68

Page: 2
Service Guide ML320/321Turbo
Chapter 1 Configuration
1.1. Standard Printer Configuration
This printer consists of the following assemblies:

Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business
Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

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Service Guide ML320/321Turbo
Chapter 1 Configuration
1.2 Options
(1) Cut sheet feeder unit (CSF)
Single-bin CSF
(2) Pull-tractor assy

(3) Bottom push tractor unit
(4) Roll paper stand (Narrow only)
(5) Serial I/F
- RS-232C

Copyright 1997, Okidata, Division of OKI America, Inc. All rights reserved. See the OKIDATA Business
Partner Exchange (BPX) for any updates to this material. (http://bpx.okidata.com)

Page: 4
Service Guide ML320/321Turbo
Chapter 2 Operation Description
2.1.1 Summary
Fig. 2-1 shows the block diagram of the printer.
The control board is made up of the microprocessors, peripheral circuits, drive circuits, sensors and
interface connectors.
The power to the control board is supplied by the power board through the connector cord.
The power to other electrical parts is also distributed through the connectors within the control board.