OKIDATA ML390 Turbo User manual

Page: 1
Service Guide ML390/ML391Turbo
Chapter 0 About This Manual
ML390 Turbo // ML391 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.
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 ML390/ML391Turbo
0 About This Manual
Front Cover 1
Copyright / About Information 2
1 Configuration
1.1. Standard Printer Configuration 3
1.2 Options 4
2 Theory of Operation
....2.1.01 Summary 5
....2.1.02 Microprocessor and the Peripheral Circuit 6
........Printer Block Diagram (Figure 2-1) 7
........Program ROM 8
........RAM (MSM51C464A-80RS) 9
........EEPROM 10
........Large Scale Integrated Chip (LSI) 11
....2.1.03 Initialization 12
....2.1.04 Parallel Interface Control 13
....2.1.05 Print Control 14
........Print Compensation Control 15
....2.1.06 Space Motor / Line Feed Motor Control 16
....2.1.07 Operation Panel 17
....2.1.08 Alarm Circuit 18
....2.1.09 Power Supply Circuit 19
2.2.01 Printhead Mechanism and Operation 20
....2.2.02 Spacing Operation 21
....2.2.03 Head Gap Adjusting 22
....2.2.04 Ribbon Drive 23
....2.2.05 Paper Feed Operation 24
........(1) Cut Sheet and Continuous Forms Switching
Mechanism 25
........(2) Cut-sheet feeder operation 26
........(3) Continuous Forms Operation (Rear) 27
........(4) Push and pull tractor mechanism (Option) 28
........(5) Pull tractor mechanism (option) 29
........(6) Bottom Push Feed Operation (Option) 30
........(7) Paper Clamp Mechanism 31
....2.2.06 Paper Detection Mechanism 32
....2.2.07 Automatic Sheet Feed 33
....2.2.08 Paper Park Function (Continuous Forms) 34
3 Assembly/Disassembly
ASSEMBLY/DISASSEMBLY 35
....3.1 Precaution for Parts Replacement 36
....3.2 Service Tools 37

Table of Contents Page
....3.3 Disassembly/Reassembly Procedure 38
............How to Change Parts 39
........3.3.01 Printhead 40
........3.3.02 Ribbon Protector 41
........3.3.03 Pull-up Roller Assy 42
........3.3.04 Upper Cover Assy, Access Cover Assy and Sheet
Guide Assy 43
........3.3.05 Gear Case Assy 44
........3.3.06 PC Connector 45
........3.3.07 Space Motor, Guide Roller Assy 46
........3.3.08 Space Rack 47
........3.3.09 Carriage Cable 48
........3.3.10 Backup Roller Holder Assy 49
........3.3.11 Platen Assy 50
........3.3.12 Driver Board (SRXD) 51
........3.3.13 LF Motor 52
........3.3.14 Operation Panel PCB (LEOP) 53
........3.3.15 Control/Power Supply Board (SRXC) 54
........3.3.16 Transformer Assy 55
........3.3.17 Change Lever and Gears 56
........3.3.18 Carriage Shaft 57
........3.3.19 Paper Pan 58
........3.3.20 Rear Tractor Assy 59
........3.3.21 Rear Pressure Assy 60
........3.3.22 Switch Lever 61
4 Adjustments
4. ADJUSTMENT 62
....4-1-1 Gap between the platen and the printhead 63
....4-1-2 Measure variation of gap when range is changed. 64
4-2 Gap between the platen and the paper pan 65
4-3 Gap between the platen and the pressure roller 66
....4-4-1 Rotation of the push tractor 67
....4-4-2 Backlash between gears 68
....4-5-1 Ribbon feed 69
....4-5-2 Running load to spacing mechanism 70
....4-6 Engagement of the double gear and the LF motor idle
gear of the Platen 71
5 Cleaning and Lubrication
5.1 Cleaning 72
5.2 Lubrication 73
....(1) Cleaning time 74
....(2) Lubricant 75
....(3) Amount of lubricant 76
....(4) Areas to Avoid 77

Table of Contents Page
........(5) Lubrication points -- 1. Ribbon feed gear Assy. 78
........2. Space rack 79
........3. Platen Assy. 80
........4. Tractor driving mechanism 81
........5. Tractor drive shaft 82
........6. Pressure roller 83
........7. Pull up roller Assy. 84
........8. Main chassis Assy. 85
........9. Carriage Assy. 86
6 Troubleshooting and Repair
6.1 Items to Check Before Repair 87
6.2 Troubleshooting Table 88
6.3 Lamp Display 89
6.4 Connection Circuit Check for Printhead and SP/LF Motor 90
........(2) Line Feed Motor 91
........(3) Space Motor 92
6.5 Troubleshooting Flow Charts 93
........2 No Spacing Operation (The Alarm LED Blinks) 94
........3 Homing does not end normally 95
........4 Paper jam while paper insertion 96
........5 Smearing/Missing Dots 97
........6 Faint or dark print 98
........7 Ribbon feed trouble 99
........8 Line feed trouble 100
........9 Malfunction of switch on operation panel 101
........10 Data receiving failure 102
A PCB Layout
APPENDIX A: PCB LAYOUT 103
B Parts Listing
SPARE PARTS LIST 104
....Upper Cover Assembly (Figure 11-1) 105
....Printer General Assembly (Figure 11-2) 106
....Printer Unit (Figure 11-3 ) [1 of 2] 107
....Printer Unit (Figure 11-3 ) [2 of 2] 108
....Carriage Option Assembly (Figure 11-4) 109
....Option Spare Parts (Figure 11-5) 110
C RS-232C Serial Interface Board
APPENDIX C: RS-232C SERIAL INTERFACE BOARD 111
C2. Operation Description 112
........C2.2.01 Operation at Power On 113
........C2.2.02 RS-232C Interface 114
....C2.3 Communication Procedure Flowchart 115
........C2.3.02 Mode B (Figure C-2-3) 116
C3. Troubleshooting Flowcharts 117

Table of Contents Page
....C3.3 Local Test 118
........C3.3.1.2 Function 119