MUTOH RJ-900 - User Manual

Technical Bulletin
tib 1006-001
RJ-900 Print Head Alignment
OVERVIEW
As with all printers produced by Mutoh, the head alignment steps on the RJ-900 and RJ-901 are quite
straightforward. These steps are common across the entire Mutoh product line although different names
may be used for each function from time to time.
This bulletin includes the relevant pages from the Mutoh service manual, along with corrections for
instructions that may be inaccurate or out of date.
MATERIALS NEEDED
• #2Philipsscrewdriver-forremovingcoverscrews
• 5xorgreaterpowerloupe
• Flashlight-asingleLEDunitsuchasaMiniMagliteispreferableduetoitsbrightness.Also,a
blueLEDlightmayhelpilluminatetheyellowalignmentpatterns,whichcanbeverydifcultto
see under normal lighting conditions.
• Atleast10to15feetofavailablepaperforprintingthealignmentpatterns.
PROCEDURE
1. StarttheprinterinSelfDiagnosticModebyholdingdowntheUP,DOWN,andRIGHTarrowkeysduring
initialization. Release the keys when the printer displays Check: Test.
2. PresstheRIGHTarrowkeytodisplayCheck:Adjustment.Makesurethatyouhavepaperloadedand
the lever is down before you press ENTER.
3. Using the menu tree shown on the following page as a guide, go through the steps in this order:
a) Nozzlecheck.Thisstepistoensurethattheheadisringproperly.
b) Slantcheck1.Inthisstep,youwillcomparetherst(black)andlast(yellow)channelsto
determineiftheheadisslanted.Thiscanbeadjustedthroughaleveronthesideofthe
head carriage.
c) Slantcheck2.Thispatterndetermineswhetherthereisaverticaladjustment(slant)to
the print head. This step is generally not necessary unless the head carriage has been
replaced or reinstalled.
d) Uni-directionalalignment.Thisadjuststheelectronictimingofeachofthe8channelson
the print head to each print mode (the print mode is a combination of head height and car-
riage speed).
e) Bi-directionalalignment.Thisisasingleadjustmentthatcompensatesforthealternating
directionsofcarriagetravelwhenprintingbi-directionally.Oneadjustmentmustbemade
for each print mode.
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Summary

Overview of RJ-900 Print Head Alignment

Procedure for RJ-900 Print Head Alignment

Nozzle Check Procedure

Ensures the print head is firing properly by checking nozzle discharge.

Slant Check 1 Procedure

Checks for print head slant in the horizontal direction using black and yellow channels.

Slant Check 2 Procedure

Checks for print head slant in the vertical direction, usually after head carriage replacement.

Uni-directional Alignment Procedure

Adjusts electronic timing for each of the 8 channels during uni-directional printing.

Bi-directional Alignment Procedure

Compensates for carriage travel direction changes in bi-directional printing.

Adjustment Menu Overview

Head Nozzle Check Menu

Confirms ink firing from nozzles after ink charge using various patterns.

CW Adjustment Menu

Adjusts print position gaps caused by CR passes using Uni-D printing.

Repeatability Adjustment Menu

Aligns head positions for repeatable printing by comparing CW and CCW print positions.

Head Alignment Adjustment (Horizontal Height)

Head Alignment Adjustment (Slant)

Overview

1. Function Description
2. Usage Features
3. Maintenance Features

This document outlines the procedure for performing print head alignment on the Mutoh RJ-900 and RJ-901 printers. The process is designed to be straightforward, consistent across Mutoh's product line, and addresses common issues that can arise with print quality.

Function Description

The RJ-900 Print Head Alignment procedure ensures optimal print quality by correcting various mechanical and electronic misalignments of the print heads. This involves a series of diagnostic checks and adjustments to ensure that ink is discharged correctly, print head slant is minimized, and both uni-directional and bi-directional printing are accurate.

The core function of this alignment process is to maintain the precision of ink droplet placement. Over time, or after maintenance such as print head replacement, the physical orientation and electronic timing of the print heads can drift, leading to issues like banding, blurred images, or inaccurate color registration. By systematically addressing these factors, the alignment procedure restores the printer's ability to produce sharp, consistent, and high-quality output.

Key aspects of the alignment include:

• Nozzle Check: Verifies that all nozzles are firing properly, identifying any clogs, omissions, or discontinuities in the ink discharge. This is a foundational step, as proper nozzle function is essential for any subsequent alignment to be effective.
• Head Slant Check (Horizontal and Vertical): Addresses the physical tilt of the print head. Horizontal slant affects the alignment of dots across the media feed direction, while vertical slant impacts the alignment of dots along the media feed. Mechanical adjustments are made to correct these slants, ensuring that the print head is perfectly perpendicular to the media.
• Uni-directional Alignment (CW and CCW): Fine-tunes the electronic timing for each of the eight ink channels during single-direction printing. This is crucial for preventing gaps or overlaps between passes when the print head moves in one direction (clockwise or counter-clockwise). Adjustments are made for different head heights and carriage speeds, which constitute various print modes.
• Bi-directional Alignment (Repeatability Adjustment): Compensates for discrepancies that occur when the print head prints in both directions (left-to-right and right-to-left). This adjustment ensures that the dots laid down during a forward pass align perfectly with those laid down during a reverse pass, eliminating banding that is characteristic of bi-directional printing errors. This is a critical step for achieving high-speed, high-quality output without visible artifacts.
• Band Feed Correction: Corrects the media feed amount for each pass, ensuring consistent media advancement and preventing banding or misregistration due to inaccurate paper movement.
• Top & Bottom Adjustment: Sets the margins at the top and bottom of the print area, ensuring consistent spacing and preventing prints from running off the media.
• P_REAR Sensor Position Adjustment: Adjusts the position of the rear sensor using cut media, which is important for accurate media detection and handling.

Usage Features

The alignment process is initiated by entering a "Self Diagnostic Mode" during printer startup, which provides access to a dedicated "Adjustment Menu." This menu guides the user through the various checks and adjustments.

• Diagnostic Mode Entry: Users access the alignment functions by holding down specific arrow keys (UP, DOWN, RIGHT) during printer initialization, which brings up the "Check: Test" display, followed by "Check: Adjustment."
• Menu-Driven Interface: The printer's control panel displays a menu tree, allowing users to navigate through different alignment steps such as "Nozzle check," "Slant check 1," "Uni-directional alignment," and "Bi-directional alignment."
• Pattern Printing: For most alignment steps, the printer prints specific test patterns on the media. These patterns are designed to visually highlight any misalignments. For example, the nozzle check prints patterns to show ink discharge, while slant checks print patterns to reveal head tilt. Uni-directional and bi-directional alignments also involve printing patterns that show the alignment of dots between passes.
• Visual Inspection and Adjustment: Users visually inspect the printed patterns using a power loupe and a flashlight (a blue LED light is recommended for yellow patterns). Based on the visual assessment, adjustments are made either mechanically (e.g., using a lever for head slant) or electronically via the printer's control panel (e.g., entering numerical values for uni-directional and bi-directional alignments). The manual provides visual guides (e.g., "Ideal," "In Spec," "Out of Spec" patterns) to help users determine the correct adjustment.
• Iterative Process: Some adjustments, particularly uni-directional and bi-directional alignments, may require an iterative process of printing a pattern, making an adjustment, and then reprinting to confirm the correction. The goal is to achieve an "Ideal" or "In Spec" alignment where dots are perfectly aligned or within a minimal tolerance.
• Print Modes: Adjustments are often specific to different print modes, which combine head height and carriage speed settings. This ensures that the printer is calibrated for various output requirements.
• Confirmation Print: After completing all necessary alignments, a confirmation print can be generated to document the final settings. This print can be stored with the printer for future reference.
• Backup and Restore: The document mentions the use of the Mutoh Maintenance Engineer Assistant program (GOTEK TIB 1006-002) to back up the machine's memory, including alignment settings. This feature is crucial for restoring settings after a major component replacement or for transferring settings between similar machines.

Maintenance Features

The alignment procedure itself is a key maintenance task, but the document also highlights specific tools and considerations for effective maintenance.

• Required Tools: The procedure specifies the need for a #2 Philips screwdriver (for cover removal), a 5x or greater power loupe (for detailed inspection of print patterns), and a flashlight (preferably a single LED unit, with a blue LED recommended for yellow patterns) to aid in visual inspection.
• Media Requirements: Sufficient paper (at least 10 to 15 feet) is required to print all the necessary alignment patterns.
• Pre-Adjustment Steps: Before performing head slant adjustments, specific printer covers (CR board cover, cable cover R) must be removed, indicating a need for careful disassembly and reassembly.
• Nozzle Cleaning: If the nozzle check reveals abnormal conditions (omission, discontinuity, meandering, satellite, T fence), the document advises performing a cleaning procedure before proceeding with further alignments. This ensures that the print head is in optimal condition for accurate calibration.
• Head Rank Input: The "Head rank input" menu item allows for entering characteristic values of the print heads, followed by ink charging. This suggests that print heads may have unique properties that need to be accounted for during setup and maintenance.
• Software Counter Initialization: The "Software counter initialization" menu item allows clearing various software counters, which can be useful for resetting operational data during maintenance.
• Documentation: The recommendation to write the date on the confirmation print and store it inside the printer's left-hand cover emphasizes the importance of maintaining a physical record of alignment history.
• Software Utility for Backup: The mention of the Mutoh Maintenance Engineer Assistant program for backing up printer memory highlights a sophisticated maintenance feature that allows for digital preservation and restoration of critical settings, reducing downtime and ensuring consistent performance across maintenance cycles.
• Power Cycle: The final step of powering off and restarting the printer normally after alignment ensures that all new settings are properly applied and the printer is ready for normal operation.

MUTOH RJ-900 Specifications

General

Type	Large Format Inkjet Printer
Print Resolution	1440 x 1440 dpi
Number of Colors	4 (CMYK)
Operating System Compatibility	Windows
Media Types	Vinyl, canvas
Connectivity	USB, Ethernet
Power Requirements	100-240 V, 50/60 Hz
Technology	Piezoelectric Inkjet