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