Contents
ML520 // ML521 Dot Matrix Printers
About This Manual
Service Guide ML520/521
Maintenance & Disassembly
Failure & Repair Analysis
Illustrated Parts Listing
Table of Contents
Service Guide ML520/521
Page
Product Specifications General Information
Printer Weight Microline
Microline
Product Specifications
Power Requirements
Ambient Temperature and Relative Humidity RH
Altitude
Product Specifications Agency Approvals 1.5.01 Listings
IPS
CPI CPS
Horiz. DPI Vert. DPI
HSD
UPC a UPC E EAN
Emulations
Front Panel Switches
Graphics Resolution
Fonts Near Letter Quality
Selects Group Function
Menu Mode Switch Action
Line Feed Increments Fixed
Form Feed / Load Selects Item
Paper Tear Capabilities
Paper Loading
Paper Out Detection
Print Method Printhead Type General Information
Auto Gap
Printhead Gap Adjustment
Gap Control
Semi Auto Gap
Print Modes
80 12 cpi 320 12 cpi 427 12 cpi
Continuous Form
Paper Specifications
Types Card Stock
Cut Sheet
Envelopes
Labels
Transparency
Number of Copies
Weight
Length
Thickness
Width
Paper
Printing Area
Eprom
Memory Specifications
Eeprom
03 RAM
Product Specifications Consumables 1.9.01 Ribbon
Dual Bin
Page
Product Specifications Pull Tractor Kit
Product Specifications Bottom Push Tractor Kit
Product Specifications Serial Interface
Product Specifications Roll Paper Stand
Product Specifications OKISmart Typer Utility
OKISmart Panel Utility
Reliability
Principles of Operation
Electrical Operation
Principles of Operation Main Control Board
Principles of Operation Block Diagram
Principles of Operation Program ROM
RAM
LSI
Service Guide ML520/521
Reset operation initiated by I-PRIME does not reset the MPU
Principles of Operation Initialization
Principles of Operation Parallel Interface Control
Principles of Operation Print Control
Principles of Operation LSI/Printhead Interface
Principles of Operation Gap Adjust Control
Principles of Operation Print Compensation Control
Also refer to .1.07 Head Drive Time
Service Guide ML520/521
Principles of Operation Line Feed Motor Control
Principles of Operation Space Motor Control
Principles of Operation Encoder Disk
Principles of Operation Operation Panel
Page
Service Guide ML520/521
Principles of Operation Low Motor Drive Voltage Alarm
Principles of Operation Head Drive Time
Less than 50%
+34 vdc or greater
Principles of Operation Head Overheat Alarm Processing
Principles of Operation Power Supply Circuit
Voltage/Signal Purpose
Service Guide ML520/521
Principles of Operation Printhead Gap Information
Page
Service Guide ML520/521
Principles of Operation Line Feed Motor Resistance
Principles of Operation Space Motor Resistance
Principles of Operation Printhead Operation
Page
Principles of Operation Printhead Temperature
Principles of Operation Spacing Mechanism
Principles of Operation Spacing Operation
Head Gap Setting Operation
Principles of Operation Head Gap Mechanism
Page
Principles of Operation Ribbon Drive Operation
Page
Principles of Operation Line Feed Mechanism
Change Lever Paper Path Selection Lever
Paper Clamp Mechanism
Page
Rear/Bottom Feed for continuous feed paper
Page
Principles of Operation Cut Sheet Paper Feed Operation
Service Guide ML520/521
Service Guide ML520/521
Service Guide ML520/521
Service Guide ML520/521
Rear Feed Detection
Bottom Feed Detection
Page
Principles of Operation Support Protector Mechanism
Principles of Operation Automatic Paper Load
Cut Sheet Paper
Principles of Operation Continuous Feed Paper
Principles of Operation Paper Park
Paper Park Operation
Maintenance & Disassembly General Information
Maintenance & Disassembly Maintenance Tools
Maintenance & Disassembly Maintenance Precautions
Handbook when the any of the following occur
Service Guide ML520/521
Maintenance & Disassembly Preliminary Items
Page
Maintenance & Disassembly Printhead Assembly
Perform this procedure
Page
Maintenance & Disassembly Ribbon Protector
Perform these procedures 3.2.01 ,
53562801 Protector Ribbon Rspl Both B.2.07
Maintenance & Disassembly Gear Case Assembly
Maintenance & Disassembly Pull-up Roller Assembly
When cleaning, refer to .4 of this Service Handbook
Page
Maintenance & Disassembly Control Board Fjim
Installation
Page
Maintenance & Disassembly Power Supply Assembly
Page
Maintenance & Disassembly Operator Panel PCB Leop
Perform these procedures 3.2.01 , 3.2.06 ,
Maintenance & Disassembly PC Connector
Perform these procedures 3.2.01 , 3.2.02 ,
56729601 Connector PC HD40 Rspl Both B.2.07
Perform these procedures 3.2.01 , 3.2.02 , 3.2.04 ,
Page
Maintenance & Disassembly Carriage Cable
Perform these procedures 3.2.01 , 3.2.06 , 3.2.07 ,
Maintenance & Disassembly Space Rack
When cleaning, refer to .4 of this Service Handbook
Page
Maintenance & Disassembly Roller/Holder Backup Assembly
Maintenance & Disassembly Guide Rail and Adjust Cam
Page
Maintenance & Disassembly Left Ground Plate
51010301 Plate Left Ground Rspl Both B.2.04
Maintenance & Disassembly Right Ground Plate
51010201 Plate Right Ground Rspl Both B.2.05
Perform these procedures 3.2.01 , 3.2.06 , 3.2.07 , 3.2.16 ,
Maintenance & Disassembly Platen Assembly
When lubricating, refer to .5 of this Service Handbook
Page
Maintenance & Disassembly Paper Chute Assembly
Page
Maintenance & Disassembly Line Feed Motor Assembly
56627201 Cord Connection Line Feed Rspl Both B.2.04
Maintenance & Disassembly Reset Spring
50923201 Spring Reset Rspl Both B.2.05
Maintenance & Disassembly Idle Gear and Change Lever
Page
Maintenance & Disassembly Pressure Spring
Page
Maintenance & Disassembly Carriage Shaft
Page
Maintenance & Disassembly Leaf Spring
Page
Maintenance & Disassembly Bottom Paper Sensor Levers
Page
Maintenance & Disassembly Front Pressure Roller Assembly
Page
Maintenance & Disassembly Tractor Assembly
Page
Page
Maintenance & Disassembly Main Frame
Service Guide ML520/521
Procedure Setup Phase
Printhead Gap Modification Phase
Parallel Adjustment Phase
Verification Phase
Page
Maintenance & Disassembly Key Combinations Description
SEL + FF/LOAD
Menu Mode
Printing the Menu
Reset Menu to Factory Defaults
Procedure
Limited Operation General Information
Page
Maintenance & Disassembly Menu Settings
Group Setting
Valid
Yes No
Page
Maintenance & Disassembly Top of Form General Information
Setting Top of Form
Reset the Top of Form to Factory Default
Maintenance & Disassembly Paper Park General Information
Procedure Continuous Feed to Single Sheet
Procedure Single Sheet to Continuous Feed
Maintenance & Disassembly Tear Feature
Maintenance & Disassembly Forms Tear Off
Vertical Line Spacing Problems
Using
Checking Top of Form with Form Tear Off Activated
Factory default Top of Form Setting is 1 inch
Cleaning Schedule
Maintenance & Disassembly
Cleaning
Cleaning Tools
Lubrication Types
Lubrication
Lubrication Schedule
Lubrication Amounts
Areas Not Lubricated
Return for Service
Shipping Instructions
All Other Returns
Failure & Repair Analysis Introduction
Service Guide ML520/521
Failure & Repair Analysis Firmware Revision Identification
Header
Service Guide ML520/521
Failure & Repair Analysis Problem Lists
Fax Number
Failure & Repair Analysis Reporting Methods Okilink
Course Critique
Mailing Address
Technical Service Bulletins
Okilink
Faxable Facts
Service Guide ML520/521
Operational Errors
Failure & Repair Analysis Problem Categories
Alarm Lamp Blinks Fatal Errors
Alarm Lamp Lights Paper End/Jam Conditions
Failure & Repair Analysis Start Here Flowchart
Start
Failure & Repair Analysis Tips for Preventing Image Problems
This Service Handbook
Failure & Repair Analysis Common Problems
Always power OFF the printer before you turn the platen knob
Page
Uneven Print Density
Smeared Print
Inconsistent Line Feed
Drifting Margin
Failure & Repair Analysis Left Margin Drifting Problem
Fault Alarms
Failure & Repair Analysis
Alar Utility PRO NLQ HSD Menu
Blinkin Kin
Refer to RAP
Page
Service Guide ML520/521
Failure & Repair Analysis RAP Index RAP Number Description
Start
Page
Failure & Repair Analysis RAP 02 No Spacing Operation
Page
Failure & Repair Analysis RAP 03 Printhead Homing Error
Page
Service Guide ML520/521
Failure & Repair Analysis RAP 05 Printhead Pins Not Firing
Failure & Repair Analysis RAP 06 Poor Print Quality
Failure & Repair Analysis RAP 07 Ribbon Feed Problem
Failure & Repair Analysis RAP 08 Line Feed Problem
Page
Failure & Repair Analysis RAP 09 Operation Panel Malfunction
Failure & Repair Analysis RAP 10 Parallel Interface Problem
Page
Failure & Repair Analysis RAP 11 Serial Interface Problem
Handbook
Printer Tests
Procedure
Page
Failure & Repair Analysis Font Test General Information
Page
Loopback Connector Configuration
Failure & Repair Analysis Serial Interface Loopback Test
Page
Failure & Repair Analysis Serial Cable Information
Service Guide ML520/521
Service Guide ML520/521
Example
Hex Data Dump
Service Guide ML520/521
Layout Diagram
Service Guide ML520/521
Failure & Repair Analysis Line Feed Motor Resistance
Failure & Repair Analysis Space Motor Resistance
Service Guide ML520/521
Chapter a Reference Charts
Description Board Designation Section Main Controller Board
Operator Panel Board
Chapter a Reference Charts Board Layout
Fuses
Switches
Firmware
Jumpers
Page
Shift
Page
Chapter a Reference Charts Power Supply Assembly Function
Page
Chapter a Reference Charts Space Motor Board Function
Page
Masked to the MPU Socket is empty
Page
Service Guide ML520/521
Chapter B Illustrated Parts Listing Format
Chapter B Illustrated Parts Listing Current Part Numbers
Remember
Rspl
520
521
Both
Placing a Parts Order
Charts
Chapter B Illustrated Parts Listing Overview
Comments
Refer to
Comments Refer to
53067201 2PA4094-7382G1 Cover Access Wide Rspl
ROM
PCB Leop
Service Guide ML520/521
Page
Service Guide ML520/521
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Service Guide ML520/521
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Page
Service Guide ML520/521
N/A
Service Guide ML520/521
PCB Lxhi
Service Guide ML520/521
PCB Ncsf
Chapter B Illustrated Parts Listing Consumables
52107001 N/A Ribbon Black Consumable Both
Comments Refer
To B.1.02
Service Guide ML520/521
Page
Okidata P/N Oki-J Description
Comments Refer
Comments Refer