Brother PT-2420PC User manual

SERVICE MANUAL
MODEL: PT-2420PC

PREFACE
This publication is a service manual covering the specifications, general mechanism,
disassembly/reassembly procedure, and troubleshooting of the Brother PT-2420PC.
It is intended for service personnel and other concerned persons to accurately and quickly provide
after-sale service for our PT-2420PC.
To perform appropriate maintenance so that the machine is always in best condition for the
customer, the service personnel must adequately understand and apply this manual.
This manual is made up of four chapters and appendixes.
CHAPTER I SPECIFICATIONS
CHAPTER II GENERAL MECHANISM
CHAPTER III DISASSEMBLY & REASSEMBLY PROCEDURE
CHAPTER IV ERROR INDICATION AND TROUBLESHOOTING
APPENDIX 1. MAINTENANCE SOFTWARE
APPENDIX 2. CIRCUIT DIAGRAM
© Copyright Brother 2002
All rights reserved.
No part of this publication may be reproduced in any
form or by any means without permission in writing
from the publisher.
Specifications are subject to change without notice.

i
CONTENTS
CHAPTER I SPECIFICATIONS......................................................................... I-1
1.1 MECHANICAL SPECIFICATIONS ........................................................................ I-1
1.1.1 External View................................................................................................. I-1
1.1.2 Control Button and LED.................................................................................. I-2
1.1.3 Printing Mechanism........................................................................................ I-2
1.1.4 Tape Cassette................................................................................................ I-3
1.1.5 Tape Cutter.................................................................................................... I-3
1.1.6 PC Interface................................................................................................... I-3
1.2 ELECTRICAL SPECIFICATIONS.......................................................................... I-4
1.2.1 Power Supply................................................................................................. I-4
CHAPTER II GENERAL MECHANISM.............................................................. II-1
2.1 MAIN MECHANISM .............................................................................................. II-1
2.1.1 Print Mechanism ............................................................................................ II-1
2.1.2 Roller Holder ASSY Setting & Retracting Mechanism..................................... II-3
2.1.3 Roller Holder ASSY & Cassette Cover Interlocking Mechanism...................... II-4
2.1.4 Tape & Ribbon Feed Mechanism.................................................................... II-5
2.1.5 Tape Cutter Mechanism ................................................................................. II-7
2.2 OUTLINE OF ELECTRONIC CONTROL............................................................... II-8
2.2.1 Configuration.................................................................................................. II-8
2.2.2 Main PCB....................................................................................................... II-9
CHAPTER III DISASSEMBLY & REASSEMBLY PROCEDURE....................... III-1
3.1 DISASSEMBLY PROCEDURE.............................................................................. III-2
[ 1 ] Removing the Tape Cassette ......................................................................... III-2
[ 2 ] Removing the Cassette Cover and Bottom Cover .......................................... III-2
[ 3 ] Removing the Main PCB ASSY...................................................................... III-4
[ 4 ] Removing the Top Cover, Sub PCB ASSY, Power Supply Actuator and
LED Cover..................................................................................................... III-5
[ 5 ] Removing the Chassis ASSY ......................................................................... III-6

ii
[ 6 ] Removing the DC Motor ASSY and Cutter ASSY........................................... III-7
[ 7 ] Removing the Roller Holder ASSY and Termal Head ASSY........................... III-8
[ 8 ] Removing the Gears ...................................................................................... III-9
[ 9 ] Removing the Switch ASSY........................................................................... III-10
3.2 REASSEMBLY PROCEDURE............................................................................... III-11
[ 1 ] Assembling the Switch ASSY......................................................................... III-11
[ 2 ] Assembling the Gears .................................................................................... III-12
[ 3 ] Assembling the Thermal Head ASSY and Roller Holder ASSY....................... III-13
[ 4 ] Assembling the Cutter ASSY and DC Motor ASSY......................................... III-15
[ 5 ] Assembling the Chassis ASSY....................................................................... III-17
[ 6 ] Assembling the LED Cover, Power Supply Actuator, Sub PCB ASSY and
Top Cover...................................................................................................... III-18
[ 7 ] Assembling the Main PCB.............................................................................. III-20
[ 8 ] Assembling the Bottom Cover, Cassette Cover and Tape Cassette................ III-24
[ 9 ] Self Print Test ................................................................................................ III-26
CHAPTER IV ERROR INDICATION AND TROUBLESHOOTING..................... IV-1
4.1 OVERVIEW .......................................................................................................... IV-1
4.2 TROUBLESHOOTING GUIDE.............................................................................. IV-1
4.3 IF THE INDICATOR LED ON THE PT-2420PC LIGHTS OR FLASHES................ IV-2
4.4 IF ANY ERROR MESSAGE IS DISPLAYED ON THE COMPUTER SCREEN....... IV-3
4.5 IF ANY OF THE FOLLOWING PROBLEMS OCCURS ......................................... IV-5
[ 1 ] Tape Feeding Failure ..................................................................................... IV-5
[ 2 ] Printing Failure............................................................................................... IV-6
[ 3 ] The Indicator LED will not come on................................................................ IV-7
[ 4 ] Interface Malfunctions.................................................................................... IV-8
Appendix 1. MAINTENANCE SOFTWARE....................................................... 1
Appendix 1.1 OVERVIEW............................................................................................. 1
Appendix 1.2 SETTING UP THE TEST ENVIRONMENT.............................................. 1
Appendix 1.3 RUNNING THE TEST PROGRAM........................................................... 2
Appendix 1.4 RUNNING THE EEPROM INITIALIZATION PROGRAM.......................... 9
Appendix 1.5 RECOVERING FROM RUN-TIME ERRORS........................................... 10
Appendix 2. CIRCUIT DIAGRAM
[ 1 ] Main PCB

I-1
CHAPTER ISPECIFICATIONS
1.1 MECHANICAL SPECIFICATIONS
1.1.1 External View
(1) Dimensions (W x D x H) 66 x 145 x 123 mm
(2) Weight
Machine proper Approx. 0.4 kg
In package Approx. 1.5 kg
Fig. 1.1-1 External View

I-2
1.1.2 Control Button and LED
(1) Number of buttons 1 (ON/OFF ( ) and FEED)
(2) LED Green
(3) Layout See Fig. 1.1-2.
Fig. 1.1-2 Layout
1.1.3 Printing Mechanism
(1) Printing method Thermal transfer onto plastic tapes (laminate tape and
non-laminate tape) or special tapes (instant lettering tape,
non-laminate thermal film tape, and iron-on transfer tape)
(Fixed thermal print head and tape feed mechanism)
(2) Printing speed 10.2 mm/sec
(3) Print head
Type Thermal print head
Heat generator Consisting of 128 heating elements vertically aligned
Size of a heating element 0.195 mm wide by 0.141 mm high
ON/OFF and FEED button
LED (Cover)
Cutter lever

I-3
1.1.4 Tape Cassette
(1) Cassette Cartridge type (TZ cassette) (AL cassette)
(2) Types of tape cassettes
•Laminated tape cassette Laminate tape, ink ribbon, and adhesive base tape
•Non-laminated tape cassette Non-laminate tape and ink ribbon
•Instant lettering tape cassette Instant lettering tape and ink ribbon
•Iron-on transfer tape cassette Iron-on transfer tape and ink ribbon
(3) Tape size
Width Length
Laminate tape 6, 9, 12, 18, 24 mm 8 m
(5 m for the fluorescent coating tape)
Non-laminate tape 6, 9, 12, 18, 24 mm 8 m
Instant lettering tape 18 mm 8 m
Non-laminate thermal film
tape 12, 18 mm 8 m
Iron-on transfer tape 18 mm 6 m
1.1.5 Tape Cutter
(1) Tape cutting method Manual cutter (Not user-replaceable)
1.1.6 PC Interface
(1) Communication interface USB
(2) Attachments
Interface cable Dedicated cable
Editor Dedicated editor

I-4
1.2 ELECTRICAL SPECIFICATIONS
1.2.1 Power Supply
(1) Power supply Dedicated AC adapter ( 9.5 VDC, 1.3A) provided
as attachment

II-1
CHAPTER II GENERAL MECHANISM
2.1 MAIN MECHANISM
2.1.1 Print Mechanism
(1) Structure of Thermal Head
This machine uses thermal transfer printing. The thermal print head has a heat generator
consisting of 128 heating elements which are vertically aligned as shown in Fig. 2.1-1.
Out of those 128 heating elements. Each heating element is 0.195 mm wide by 0.141 mm
high.
Fig. 2.1-1 Heat Generator of Thermal Head
(2) Printing Process
When the cylindrical rubber platen is pressed against the thermal print head with the tape*
and ink ribbon** sandwiched inbetween, the CPU applies electric power to the selected ones
of those 128 heating elements.
* Laminate tape when using laminated tape cassettes.
Non-laminated tape when using non-laminated tape cassettes.
Instant lettering tape when using instant lettering tape cassettes.
Iron-on transfer tape when using iron-on transfer tape cassettes.
** When using non-laminated thermal film tape cassettes, no ink ribbon is sandwiched.
[For tape cassettes except non-laminated thermal film tape cassettes]
If the selected heating element(s) generates heat, the ink on the sandwiched ribbon will be
melted and transferred to the tape, producing a dot(s) on the tape. The ink ribbon and the
tape are advanced and then the next heating cycle is repeated, thus forming a character on
the tape.
[For non-laminated thermal film tape cassettes]
If the selected heating element(s) generates heat, the thermal film tape develops itself to
produce a dot(s) on the tape. The tape is advanced and the next heating cycle is repeated,
thus forming a character on the tape.

II-2
For laminated tape cassettes, instant lettering tape cassettes, and iron-on transfer tape
cassettes, the CPU processes the print data to generate a mirror image so that the printed
character can be seen normally when viewed from the other side of the printed face of the
tape.
(3) Character Formation
While the tape feed motor (DC motor) feeds the tape and ink ribbon (tape only when using
non-laminated thermal film tape cassettes) by 0.141 mm for 13.8 ms, the thermal head
generates heat once. The feed amount of 0.141 mm is smaller than the width (0.195 mm)
of the heating elements so that the heat generated at one heating cycle will overlap with the
next heating cycle. This forms a character having no gap between adjacent printed dots.

II-3
2.1.2 Roller Holder ASSY Setting & Retracting Mechanism
This mechanism consists of the roller release lever, roller release rod, and roller holder ASSY.
The roller holder supports the platen and tape feed sub roller so that they can move
perpendicularly to the thermal head and tape feed roller built in the tape cassette, respectively, as
well as rotating freely.
Loading a tape cassette and closing the cassette cover pushes down the roller release lever which
moves the roller release rod to the left as illustrated below. This pivots the roller holder ASSY
around the shaft provided on the chassis so as to press the roller holder ASSY against the thermal
head side.
The platen is pressed perpendicularly against the thermal head with the tape and ink ribbon (only
the tape when using non-laminated thermal film tape cassettes) sandwiched inbetween under a
uniform load by the roller holder springs. At the same time, the platen gear becomes engaged
with the P idle gear.
Also, the tape feed sub roller is pressed perpendicularly against the tape feed roller built in the
tape cassette with the tape (and base paper when using laminated tape cassettes) sandwiched
inbetween under a uniform load by the roller holder springs. At the same time, the sub roller gear
becomes engaged with the tape idle gear.
If you open the cassette cover, the roller release lever pops up so that the roller release rod
retracts the roller holder ASSY from the thermal head, providing you with enough space to replace
the tape cassette.
Fig. 2.1-2 Roller Holder ASSY Setting & Retracting Mechanism
Adhesive base tape
Platen
Thermal head ASSY
Tape cassette
P idle gear
Tape feed roller built
in a tape cassette
(Tape idle gear)
Tape feed sub roller
Roller release rod Roller release lever
Ink ribbon
Laminate tape
Roller holder ASSY
Platen gear Roller holder spring, lower
(Top)
Sub roller gear
Tape feed sub roller Platen
Roller holder spring, upper

II-4
2.1.3 Roller Holder ASSY & Cassette Cover Interlocking Mechanism
Closing the cassette cover pushes down the roller release lever and brings the top of the lever into
the box provided on the inside of the cassette cover.
As described in Subsection 2.1.2 “Roller Holder ASSY Setting & Retracting Mechanism”, the roller
release lever shifts the roller release rod so that the roller holder ASSY is pressed towards the
thermal head side.
Fig. 2.1-3 Roller Release Lever and Roller Release Rod
Fig. 2.1-4 Roller Holder ASSY & Cassette Cover Interlocking Mechanism
If you open the cassette cover, the roller release lever will pop up, shifting the roller release rod so
that the roller holder ASSY will be retracted from the thermal head side.
Tape cassette
Roller holder ASSY Roller release lever
Thermal head
Roller release lever
Roller release rod
Roller holder ASSY
Roller release rod
(Roller holder ASSY engaged)(Roller holder ASSY retracted)
Cassette cover
Roller release lever

II-5
2.1.4 Tape & Ribbon Feed Mechanism
This mechanism consists of a DC motor, gear train, and roller holder ASSY.
(1) Tape Feeding
When you load a tape cassette and close the cassette cover, the platen and the thermal
head sandwich the tape and ink ribbon (only the tape when using non-laminated thermal file
tape cassettes) inbetween. Also, the tape feed sub roller in the roller holder ASSY and the
tape feed roller inside the tape cassette sandwich the tape (and base paper when using
laminated tape cassettes) inbetween, as described in Subsection 2.1.2.
As the DC motor rotates, the rotation is transmitted via the gear train to the P idle gear
(which rotates the platen gear) and the tape idle gear (which rotates the tape feed roller and
tape feed sub roller at the same rotation speed).
Accordingly, the sandwiched tape and ink ribbon will be advanced. (When a laminated tape
cassette is mounted, the sandwiched laminate tape, adhesive base tape, and ink ribbon will
be advanced together.)
The feeding amount of the platen is slighty less than that of the tape feed sub roller.
Fig. 2.1-5 Tape Feeding Mechanism
Adhesive base tape
P idle gear
Chassis
DC motor
Roller holder ASSY
Tape idle gear
Platen
P idle gear
Tape feed roller
(Tape idle gear)
Tape feed sub roller
Thermal head
Transparent laminate tape

II-6
(2) Adhesive Base Tape Feeding (only for laminated tape cassettes)
A laminated tape cassette contains both a transparent laminate tape roll and a separate
adhesive base tape roll.
When a transparent laminate tape and adhesive base tape pass through the contact point
(between the tape feed roller and tape feed sub roller), they are then bonded together into a
single, printed tape. The ink printed on the laminate tape is, therefore, sealed up with the
adhesive base tape.
(3) Ink Ribbon Feeding (except for non-laminated thermal film tape cassettes)
As the DC motor rotates, the ribbon drive cam located at the middle of the gear train rotates
counterclockwise. When fitted on the ribbon drive cam, the ribbon take-up roll in the tape
cassette also rotates to take up the ink ribbon.
To apply proper tension to the ink ribbon between the platen and the ribbon drive cam, the
feed amount of the ribbon drive cam is slightly greater than that of the tape feed gear. The
difference between the tape feed speeds at the platen and at the ribbon drive cam is
absorbed by the clutch spring which is integrated in the ribbon drive cam and allows the cam
to slip.
This way, the ink ribbon is kept tense, which enables the ribbon to clearly separate from the
tape at the stabilized angle after printing.
Fig. 2.1-6 Ribbon Feeding Mechanism
Adhesive base tape
P idle gear
Tape idle gear Ribbon drive cam
Chassis
DC motor
Platen
Tape idle gear
Tape feed sub roller
Roller holder ASSY Thermal head
Ink ribbon
Ribbon take-up roll
Transparent laminate tape

II-7
2.1.5 Tape Cutter Mechanism
The tape cutter ASSY consists of a stationary blade and movable blade.
The printed tape will come through those blades. Pressing the cutter lever will drive the cutter
drive gear whose pin will move the movable blade, cutting the printed tape, just like a scissors.
Fig. 2.1-7 Tape Cutter Mechanism
Stationary blade Tape cassette
Pin of the cutter drive gear
Cutter lever
Movable blade

II-8
2.2 OUTLINE OF ELECTRONIC CONTROL
2.2.1 Configuration
Fig. 2.1-1 shows a block diagram of the control electronics of this machine. The control
electronics consists of a main PCB, DC motor, and thermal print head ASSY.
Fig. 2.2-1 Control Electronics of PT-2420PC
(1) Main PCB
This manages all the components including an LED, ON/OFF switch, DC motor, thermal
print head ASSY, and USB interface.
(2) Sub PCB
This holds the ON/OFF switch (ON/OFF and FEED) and an indicator LED (green).
(3) DC Motor
The DC motor is a power source to advance tape (and ink ribbon).
(4) Thermal Print Head
This is a thick-film thermal print head which integrates a heat generator (consisting of 128
heating elements vertically aligned in 180 dpi) and driver circuitry.
(5) Switch ASSY (cassette sensor)
According to the states of the five sensor switches on the switch ASSY, the CPU may
identify the tape width and type of the tape cassette loaded.

II-9
2.2.2 Main PCB
Fig. 2.2-2shows a block diagram of the main PCB. The main PCB consists of the following:
(1) CPU (including a ROM and RAM)
(2) SRAM (256-kilobyte)
(3) EEPROM (1-kilobit)
(4) USB interface circuit
(5) LED ON/OFF circuit, thermal head control circuit, and motor driver circuit
(6) Reset circuit
(7) Oscillator circuit
(8) Cassette sensor circuit and cutter sensor circuit
(9) Head property detector circuit
(10) Voltage detector circuit and ambient temperature detector circuit
(11) ON/OFF switch circuit
Fig. 2.2-2 Block Diagram of Main PCB

III-1
CHAPTER III DISASSEMBLY & REASSEMBLY PROCEDURE
Safety Precautions
(1) You should carry out disassembly & reassembly jobs on an anti-static sheet grounded
correctly. Otherwise, the LSI and other electronic devices will be damaged due to
the electricity charged in your body.
(2) When transporting PCBs, be sure to wrap them in conductive sheets such as
aluminum foil.
(3) When using soldering irons and other heat-generating tools, take care not to
damage the resin parts such as wires, PCBs, and covers.
(4) Be careful not to lose screws, washers, or other parts removed for parts
replacement.
(5) Tighten screws to the torque values listed below.
Tightening Torque List
Location Screw type Q’ty Tightening torque
Middle cover Taptite, bind B M2.6 x 8 50.39 ±0.10 N•m (4 ±1 kgf•cm)
Chassis sub ASSY Taptite, bind B M2.6 x 6 20.39 ±0.10 N•m (4 ±1 kgf•cm)
DC motor Screw, pan M1.7x2.5 20.15 ±0.05 N•m (1.5 ±0.5 kgf•cm)
Cutter ASSY Taptite, cup S M3x5 10.59 ±0.10 N•m (6 ±1 kgf•cm)
Head ASSY Screw, bind M3x4 10.59 ±0.10 N•m (6 ±1 kgf•cm)
Sub PCB ASSY Taptite, bind B M2.6 x 8 10.39 ±0.10 N•m (4 ±1 kgf•cm)
Main PCB Taptite, bind B M2.6 x 8 10.39 ±0.10 N•m (4 ±1 kgf•cm)
Ground wire Taptite, bind B M2.6 x 6 10.39 ±0.10 N•m (4 ±1 kgf•cm)

III-2
3.1 DISASSEMBLY PROCEDURE
[ 1 ] Removing the Tape Cassette
(1) Open the cassette cover while holding down the section “A” of the cassette cover.
(2) Take the tape cassette out of the machine by holding both sides of the cassette.
Note: When opening the cassette cover, the platen is released from the thermal head so that
there is a gap between them to make possible to replace the tape cassette.
Fig. 3.1-1 Removing the Tape Cassette
[ 2 ] Removing the Cassette Cover and Bottom Cover
(1) Pull the arms of the cassette cover outwards to remove the cassette cover from the middle
cover.
Fig. 3.1-2 Removing the Cassette Cover
“A”
Tape cassette
Cassette cover
Arm
Middle cover
Arm
Cassette cover

III-3
(2) Remove the five screws securing the bottom cover.
Fig. 3.1-3 Removing the Bottom Cover (1)
(3) Turn the machine upside down so that the bottom cover is at the top. Remove the bottom
cover.
Fig. 3.1-4 Removing the Bottom Cover (2)
Screws Screws
Bottom cover