JUKI LK-1900AN Quick start guide

40111443
No. E402-00
ENGINEER’S MANUAL
LK-1900AN Series
Computer-controlled High-speed
Bartacking Machine

PREFACE
This Engineer’s Manual is written for the technical personnel who are responsible for the service and
maintenance of the machine.
The Instruction Manual for these machines intended for the maintenance personnel and operators at
an apparel factory contains operating instruction in detail. And this manual describes “Standard Adjust-
ment”, “Adjustment Procedures”, “Results of Improper Adjustment”, and other important information
which are not covered in the Instruction Manual.
When carrying out the maintenance work on the sewing machine, be sure to refer also to the Instruction
Manual and the Parts List.
In addition, for the motor for the sewing machine with thread trimmer, refer to the separate Instruction
Manual or This manual gives the “Standard Adjustment” on the former page under which the most basic
adjustment value is described, and on the latter page “Results of Improper Adjustment” under which
stitching errors and troubles arising from mechanical failures and “How to adjust” are described.

i
For the sewing machine, automatic machine and ancillary devices (hereinafter collectively referred to as
"machine"), it is inevitable to conduct sewing work near moving parts of the machine. This means that there
is always a possibility of unintentionally coming in contact with the moving parts. Operators who actually
operate the machine and maintenance personnel who are involved in maintenance and repair of the
machine are strongly recommended to carefully read to fully understand the following Safety precautions
of this engineer's manual before using/maintaining the machine. The content of the Safety precautions of
this engineer's manual includes items which are not contained in the specications of your product.
The risk indications are classied into the following three different categories to help understand the meaning
of the labels of this engineer's manual and the product. Be sure to fully understand the following description
and strictly observe the instructions.
(
!
) Explanation of risk levels
(
@
) Explanation of pictorial warning indications and warning labels
Warning label
1
2
3
1 • There is the possibility that slight to serious injury or death may be caused.
• There is the possibility that injury may be caused by touching moving part.
2• To perform sewing work with safety guard.
• To perform sewing work with safety cover.
• To perform sewing work with safety protection device.
3 • Be sure to turn the power OFF before carrying out "machine-head threading,"
"needle changing," "bobbin changing" or "oiling and cleaning.
3
2
1
Electrical-shock
danger label
DANGER :
This indication is given where there is an immediate danger of death or serous injury if the person in charge or any third
party mishandles the machine or does not avoid the dangerous situation when operating or maintaining the machine.
WARNING :
This indication is given where there is a potentiality for death or serious injury if the person in charge or any third party
mishandles the machine or does not avoid the dangerous situation when operating or maintaining the machine.
CAUTION :
This indication is given where there is a danger of medium to minor injury if the person in charge or any third party
mishandles the machine or does not avoid the dangerous situation when operating or maintaining the machine.
Items requiring special attention
Pictorial warning indication
There is a risk of injury if contact-
ing a moving section.
Pictorial warning
indication
Be aware that holding the sewing
machine during operation can
hurt your hands.
There is a risk of electrical shock if
contacting a high-voltage section.
There is a risk of entanglement
in the belt resulting in injury.
There is a risk of a burn if contact-
ing a high-temperature section.
There is a risk of injury if you
touch the button carrier.
Be aware that eye deciency can
be caused by looking directly at
the laser beam.
Indication label
The correct direction is indicat-
ed.
There is a risk of contact between
your head and the sewing ma-
chine.
Connection of a earth cable is
indicated.
TO ENSURE SAFE USE OF YOUR SEWING MACHINE
Adjustment :
It means replacement of parts,
disassembly, and repair assembly.

ii
Accident means "to cause
personal injury or death or
damage to property."
Turning the power off: Turning the power switch off, then removing the power plug from the outlet. This
applies to the following.
1. When it is necessary to open the control box containing electrical parts, be sure to turn the power off and
wait for ve minutes or more before opening the cover in order to prevent accident leading to electrical
shock.
Basic precaution
1. Be sure to read the engineer's manual and other explanatory documents supplied with accessories of
the machine before using the machine. Carefully keep the engineer's manual and the explanatory docu-
ments at hand for quick reference.
2. The content of this section includes items which are not contained in the specications of your product.
3. Be sure to wear safety goggles to protect against accident caused by needle breakage.
4. Those who use a heart pacer have to use the machine after consultation with a medical specialist.
Safety devices and warning labels
1. Be sure to operate the machine after verifying that safety device(s) is correctly installed in place and
works normally in order to prevent accident caused by lack of the device(s).
2. If any of the safety devices is removed, be sure to replace it and verify that it works normally in order to
prevent accident that can result in personal injury or death.
3. Be sure to keep the warning labels adhered on the machine clearly visible in order to prevent accident
that can result in personal injury or death. If any of the labels has stained or come unstuck, be sure to
change it with a new one.
Application and modication
1. Never use the machine for any application other than its intended one and in any manner other than that
prescribed in the engineer's manual in order to prevent accident that can result in personal injury or death.
JUKI assumes no responsibility for damages or personal injury or death resulting from the use of the
machine for any application other than the intended one.
2.
Never modify and alter the machine in order to prevent accident that can result in personal injury or death.
JUKI assumes no responsibility for damages or personal injury or death resulting from the machine
which has been modied or altered.
Education and training
1. In order to prevent accident resulting from unfamiliarity with the machine, the machine has to be used
only by the operator who has been trained/educated by the employer with respect to the machine opera-
tion and how to operate the machine with safety to acquire adequate knowledge and operation skill. To
ensure the above, the employer has to establish an education/training plan for the operators and edu-
cate/train them beforehand.
Items for which the power to the machine has to be turned off
1. Be sure to immediately turn the power off if any abnormality or failure is found or in the case of power
failure in order to protect against accident that can result in personal injury or death.
2. To protect against accident resulting from abrupt start of the machine, be sure to carry out the follow-
ing operations after turning the power off. For the machine incorporating a clutch motor, in particular,
be sure to carry out the following operations after turning the power off and verifying that the machine
stops completely.
2-1. For example, threading the parts such as the needle, looper, spreader etc. which have to be
threaded, or changing the bobbin.
2-2. For example, changing or adjusting all component parts of the machine.
2-3. For example, when inspecting, repairing or cleaning the machine or leaving the machine.
3. Be sure to remove the power plug by holding the plug section instead of the cord section in order to pre-
vent electrical-shock, earth-leakage or re accident.
4. Be sure to turn the power off whenever the machine is left unattended between works.
5. Be sure to turn the power off in the case of power failure in order to prevent accident resulting of break-
age of electrical components.
PRECAUTIONS TO BE TAKEN IN VARIOUS OPERATION STAGES
Transportation
1. Be sure to lift and move the machine in a safe manner taking the machine weight in consideration. Refer
to the text of the engineer's manual for the mass of the machine.
CAUTION
DANGER
SAFETY PRECAUTIONS

iii
2. Be sure to take sufcient safety measures to prevent falling or dropping before lifting or moving the
machine in order to protect against accident that can result in personal injury or death.
3. Once the machine has been unpacked, never re-pack it for transportation to protect the machine against
breakage resulting from unexpected accident or dropping.
Unpacking
1. Be sure to unpack the machine in the prescribed order in order to prevent accident that can result in
personal injury or death. In the case the machine is crated, in particular, be sure to carefully check nails.
The nails have to be removed.
2. Be sure to check the machine for the position of its center of gravity and take it out from the package
carefully in order to prevent accident that can result in personal injury or death.
Installation
(!)Table and table stand
1. Be sure to use JUKI genuine table and table stand in order to prevent accident that can result in per-
sonal injury or death. If it is inevitable to use a table and table stand which are not JUKI genuine ones,
select the table and table stand which are able to support the machine weight and reaction force during
operation.
2. If casters are tted to the table stand, be sure to use the casters with a locking mechanism and lock
them to secure the machine during the operation, maintenance, inspection and repair in order to prevent
accident that can result in personal injury or death.
(@)Cable and wiring
1. Be sure to prevent an extra force from being applied to the cable during the use in order to prevent
electrical-shock, earth-leakage or re accident. In addition, if it is necessary to cable near the operating
section such as the V-belt, be sure to provide a space of 30 mm or more between the operating section
and the cable.
2. Be sure to avoid starburst connection in order to prevent electrical-shock, earth-leakage or re accident.
3. Be sure to securely connect the connectors in order to prevent electrical-shock, earth-leakage or re ac-
cident. In addition, be sure to remove the connector while holding its connector section.
(#)Grounding
1. Be sure to have an electrical expert install an appropriate power plug in order to prevent accident
caused by earth-leakage or dielectric strength voltage fault. In addition, be sure to connect the power
plug to the grounded outlet without exceptions.
2. Be sure to ground the earth cable in order to prevent accident caused by earth leakage.
($)Motor
1. Be sure to use the specied rated motor (JUKI genuine product) in order to prevent accident caused by
burnout.
2. If a commercially available clutch motor is used with the machine, be sure to select one with an entan-
glement preventive pulley cover in order to protect against being entangled by the V-belt.
Before operation
1. Be sure to make sure that the connectors and cables are free from damage, dropout and looseness be-
fore turning the power on in order to prevent accident resulting in personal injury or death.
2. Never put your hand into the moving sections of the machine in order to prevent accident that can result
in personal injury or death.
In addition, check to be sure that the direction of rotation of the pulley agrees with the arrow shown on pulley.
3. If the table stand with casters is used, be sure to secure the table stand by locking the casters or with
adjusters, if provided, in order to protect against accident caused by abrupt start of the machine.
During operation
1. Be sure not to put your ngers, hair or clothing close to the moving sections such as the handwheel,
hand pulley and motor or place something near those sections while the machine is in operation in order
to prevent accident caused by entanglement that can result in personal injury or death.
2. Be sure not to place your ngers near the surround area of the needle or inside the thread take-up lever
cover when turning the power on or while the machine is in operation in order to prevent accident that
can result in personal injury or death.
3. The machine runs at a high speed. Never bring your hands near the moving sections such as looper,
spreader, needle bar, hook and cloth trimming knife during operation in order to protect your hands
against injury. In addition, be sure to turn the power off and check to be sure that the machine complete-
ly stops before changing the thread.
4. Be careful not to allow your ngers or any other parts of your body to be caught between the machine
and table when removing the machine from or replacing it on the table in order to prevent accident that
can result in personal injury or death.
5.
Be sure to turn the power off and check to be sure that the machine and motor completely stop before remov-
ing the belt cover and V-belt in order to prevent accident caused by abrupt start of the machine or motor.
6. If a servomotor is used with the machine, the motor does not produce noise while the machine is at rest.
Be sure not to forget to turn the power off in order to prevent accident caused by abrupt start of the motor.
7. Never use the machine with the cooling opening of the motor power box shielded in order to prevent re
accident by overheat.

iv
Lubrication
1. Be sure to use JUKI genuine oil and JUKI genuine grease to the parts to be lubricated.
2.
If the oil adheres on your eye or body, be sure to immediately wash it off in order to prevent inammation or irritation.
3. If the oil is swallowed unintentionally, be sure to immediately consult a medical doctor in order to pre-
vent diarrhea or vomiting.
Maintenance
1. In prevention of accident caused by unfamiliarity with the machine, repair and adjustment has to be car-
ried out by a service technician who is thoroughly familiar with the machine within the scope dened in
the engineer's manual. Be sure to use JUKI genuine parts when replacing any of the machine parts. JUKI
assumes no responsibility for any accident caused by improper repair or adjustment or the use of any
part other than JUKI genuine one.
2. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure
to ask an electrical technician of your company or JUKI or distributor in your area for repair and mainte-
nance (including wiring) of electrical components.
3. When carrying out repair or maintenance of the machine which uses air-driven parts such as an air cyl-
inder, be sure to remove the air supply pipe to expel air remaining in the machine beforehand, in order to
prevent accident caused by abrupt start of the air-driven parts.
4. Be sure to check that screws and nuts are free from looseness after completion of repair, adjustment
and part replacement.
5. Be sure to periodically clean up the machine during its duration of use. Be sure to turn the power off and
verify that the machine and motor stop completely before cleaning the machine in order to prevent ac-
cident caused by abrupt start of the machine or motor.
6. Be sure to turn the power off and verify that the machine and motor stop completely before carrying out
maintenance, inspection or repair of the machine. (For the machine with a clutch motor, the motor will
keep running for a while by inertia even after turning the power off. So, be careful.)
7. If the machine cannot be normally operated after repair or adjustment, immediately stop operation and
contact JUKI or the distributor in your area for repair in order to prevent accident that can result in per-
sonal injury or death.
8.
If the fuse has blown, be sure to turn the power off and eliminate the cause of blowing of the fuse and re-
place the blown fuse with a new one in order to prevent accident that can result in personal injury or death.
9. Be sure to periodically clean up the air vent of the fan and inspect the area around the wiring in order to
prevent re accident of the motor.
Operating environment
1. Be sure to use the machine under the environment which is not affected by strong noise source (electro-
magnetic waves) such as a high-frequency welder in order to prevent accident caused by malfunction of
the machine.
2. Never operate the machine in any place where the voltage uctuates by more than "rated voltage ±10 %"
in order to prevent accident caused by malfunction of the machine.
3. Be sure to verify that the air-driven device such as an air cylinder operates at the specied air pressure
before using it in order to prevent accident caused by malfunction of the machine.
4.
To use the machine with safety, be sure to use it under the environment which satises the following conditions:
Ambient temperature during operation 5℃ to 35℃
Relative humidity during operation 35 % to 85 %
5.
Dew condensation can occur if bringing the machine suddenly from a cold environment to a warm one. So,
be sure to turn the power on after having waited for a sufcient period of time until there is no sign of wa-
ter droplet in order to prevent accident caused by breakage or malfunction of the electrical components.
6. Be sure to stop operation when lightning ashes for the sake of safety and remove the power plug in
order to prevent accident caused by breakage or malfunction of the electrical components.
7. Depending on the radio wave signal condition, the machine may generate noise in the TV or radio. If this
occurs, use the TV or radio with kept well away from the machine.
8. For the worker who is involved in the work to be done in the environment relevant to "noise value in the
working environment is 85 dB or more and less than 90 dB", be sure to take appropriate measures, as
required, such as the use of ear protection or the like to protect against health hazard. In addition, for the
worker who is involved in the work to be done in the environment relevant to "noise level in the working
environment is 90 dB or more," be sure to instruct him/her to wear ear protection without exceptions in
order to protect against health hazard, and display a sign explaining how to use the ear protection at an
easily viewable location for the worker.
9. Disposal of products and packages and treatment of used lubricating oil should be carried out properly
according to the relevant laws of the country in which the sewing machine is used.

v
Transportation
1. Be sure to lift this machine with two or more workers and use a carriage for moving it in order to prevent
personal injury.
2. Be sure to take sufcient safety measures to prevent falling or dropping before lifting or moving the
machine in order to protect against accident that can result in personal injury or death.
3. Installation is described in the Instruction Manual. Be sure to fully understand the description before
putting the machine into operation.
Replacement of parts
1. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure
to ask an electrical technician of your company or JUKI or distributor in your area for replacement of
electrical components.
2. When it is necessary to open the control box containing electrical parts, be sure to turn the power off
and wait for ve minutes or more before opening the cover in order to prevent accident caused by un-
familiarity with the machine or electrical-shock accident. In addition, do not carry out replacement work
with wet hands in order to prevent electrical-shock accident.
3. Be sure to replace parts according to the instructions given in this Engineer's Manual and in the Instruc-
tion Manual in order to protect against accident that can result in personal injury.
4. Be sure to carry out replacement work after having installed the machine in a stable state in order to
protect against accident that can result in personal injury.
In addition, be sure to select appropriate tools.
5. Make sure, after the completion of replacement work, that there is no loose soldering, no contact with
other parts, inadequate contact between connectors and receptacles, and loose screws/nuts in order to
protect against accident that can result in personal injury.
6. Make sure, after the completion of replacement work, that neither connectors nor cables are damaged,
slipped off or loosened in order to protect against accident that can result in personal injury.
It should be remembered that some parts have been factory-insulated with tubes or tapes, or oated
above the PWB for safety's sake. In addition, internal wiring has been factory-routed or -clamped in such
a way that it does not come close to high-voltage parts. Be sure to re-place those parts as they are at the
time of delivery.
7. Be sure to use JUKI genuine parts when replacing any of the machine parts.
JUKI assumes no responsibility for any accident caused by any part other than JUKI genuine one.
In addition, in the event you cannot replace parts within the specied range, immediately stop the re-
placement work and ask JUKI or distributor in your area for replacement of the parts.
8. If the fuse has blown, be sure to turn the power off and eliminate the cause of blowing of the fuse and
replace the blown fuse with a new one in order to prevent accident that can result in personal injury or
death.
Adjustment
1. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure
to ask an electrical technician of your company or JUKI or distributor in your area for adjustment of
electrical components.
2. When it is necessary to open the control box containing electrical parts, be sure to turn the power off
and wait for ve minutes or more before opening the cover in order to prevent accident caused by un-
familiarity with the machine or electrical-shock accident. In addition, do not carry out adjustment work
with wet hands in order to prevent electrical-shock accident.
3. In prevention of accident that can result in personal injury, adjust adjustment variable resistor or the
like installed on PWB within the specied range given in this Engineer's Manual and in the Instruction
Manual.
4. Be sure to carry out replacement work after having installed the machine in a stable state in order to
protect against accident that can result in personal injury.
In addition, be sure to select appropriate tools.
5. In prevention of accident that can result in personal injury, make sure, after the completion of adjust-
ment work, that neither screws nor nuts are loosened or come in contact with other parts.
6. Make sure, after the completion of replacement work, that neither connectors nor cables are damaged,
slipped off or loosened in order to protect against accident that can result in personal injury.
7. In prevention of accident that can result in personal injury or entanglement accident, be sure to ensure
safety at the time of test run. In addition, be sure to take care not to allow hair or cloths to come in con-
tact with the machine belt.
Disassembly/assembly
1. In prevention of accident that can result in personal injury, be sure to carry out disassembly/assembly
work within the specied range given in this Engineer's Manual and in the Instruction Manual.
PRECAUTIONS TO BE TAKEN IN VARIOUS OPERATION STAGES
Electrical components
CAUTION

vi
Precautions to be taken so as to use the LK-1900AN Series more safely
1. To avoid electrical shock hazards, neither open the cover of the electrical box for the motor
nor touch the components mounted inside the electrical box.
2. After changing the pattern, make sure the needle entry point. If the pattern is protruded
from the work clamp feet, the needle will interfere with the work clamp feet during sewing,
and it is dangerous due to the needle breakage or the like.
3. Do not turn OFF the power in a state that the needle is lowered. Wiper may break the nee-
dle.
1. In case nothing is displayed in the operation panel even when the power switch is turned
ON, turn OFF the power switch and check the power voltage and phase.
2. To prevent personal injury or death, never put ngers into the thread take-up lever, work
clamp, work clamp mechanism and thread take-up cover, and under or near the cloth cut-
ting knife and needle when turning on the power switch or while the machine is in opera-
tion.
3. To protect against possible accidents due to abrupt startup of the machine, turn OFF the
power switch before tilting the machine head or removing the motor cover.
4. So as to prevent possible accidents caused by abrupt start of the sewing machine, depress
the start switch after ascertaining that there is no interfering thing under the needle when
winding the bobbin thread. In addition, never put your hair close to the machine during
thread trimming.
2. In prevention of accident caused by unfamiliarity with the machine or electrical-shock accident, be sure
to ask an electrical technician of your company or JUKI or distributor in your area for disassembly/as-
sembly of electrical components.
3. When it is necessary to open the control box containing electrical parts, be sure to turn the power off
and wait for ve minutes or more before opening the cover in order to prevent accident caused by unfa-
miliarity with the machine or electrical-shock accident. In addition, do not carry out disassembly/assem-
bly work with wet hands in order to prevent electrical-shock accident.
4. Be sure to carry out replacement work after having installed the machine in a stable state in order to
protect against accident that can result in personal injury.
In addition, be sure to select appropriate tools.
5. In prevention of accident that can result in personal injury, be sure to tighten screws and nuts in assem-
bly work with a specied torque, if specied, or with an appropriate torque, if not specied.
After the completion of assembly work, be sure to check that screws and nuts are not loosened before
starting test run.
6. In prevention of accident that can result in personal injury, make sure, after the completion of adjust-
ment work, that neither screws nor nuts are loosened or come in contact with other parts.
7. Make sure, after the completion of replacement work, that neither connectors nor cables are damaged,
slipped off or loosened in order to protect against accident that can result in personal injury.
It should be remembered that some parts have been factory-insulated with tubes or tapes, or oated
above the PWB for safety's sake. In addition, internal wiring has been factory-routed or -clamped in
such a way that it does not come close to high-voltage parts. Be sure to re-place those parts as they are
at the time of delivery.
8. In prevention of accident that can result in personal injury, be sure to check whether the direction of
rotation is correct at the time of test run.
9. In prevention of accident that can result in personal injury or entanglement accident, be sure to ensure
safety at the time of test run. In addition, be sure to take care not to allow hair or cloths to come in con-
tact with the machine belt.

vii
5. Feeding frame automatically comes down when pattern is changed, ready key is ON, Press-
er switch is ON, intermediate presser button is ON and bobbin winder button is ON. To
prevent possible accidents caused by abrupt start of the sewing machine, never place your
ngers under the feeding frame.
6. To avoid personal injury, never bring your ngers, hair or clothing close to V belt, cloth cut-
ting knife or motor during operation, and never place anything on any of these parts.
7. To avoid personal injury, never operate the machine with the motor cover, eye protection
cover, or any other safety devices removed.
8. To prevent personal injury or death, do not operate the sewing machine with its covers re-
moved.
9. The operation panel displays safety warnings. It is necessary therefore to rst verify normal
display on the panel when the power switch is turned on, before operating the sewing ma-
chine.
10. To prevent personal injury or death, do not press the hand pulley while the sewing machine
is in operation.
11. To avoid personal injury, be careful never to allow your ngers to go inside the machine
when tilting or raising the machine head.
12. To prevent possible accidents due to electric shocks or damaged electrical component(s),
always turn OFF the power switch before connecting or disconnecting the power plug.
13. During thunder and lightning storms, stop your work and disconnect the power from
the outlet to ensure safety and prevent possible accidents due to damaged electrical
component(s).
14. If the machine is suddenly moved from a cold place to a warm place, dew condensation
may result. If this occurs, be sure to conrm that there are no potentially dangerous water
drops in the machine before turning it on in order to prevent possible accidents due to dam-
aged electrical component(s).
15. In the event of a power failure, be sure to turn OFF the power to the machine to protect
against damaged electrical components.
16. This sewing machine should be used under industrial environment. Under general house-
hold environment, the machine may cause poor reception when used in proximity of the
television set or radio.
17. When the sewing machine is used without a break for many hours, the temperature of a part
of the machine body or the rear side of operation panel rises higher by 15˚C than the envi-
ronmental temperature, and you may feel the heat from the part. However, this phenomenon
is not abnormal, and does not affect the components or the like.
18. Do not lubricate the machine oil to the places other than the oil tank and the hook section.
The grease lubricating system except the hook section is employed for this sewing ma-
chine, and the grease ows out when lubricating the machine oil resulting in worn-out of
the components.
19. Be careful of handling this product so as not to pour water or oil, shock by dropping, and
the like since this product is a precision instrument.
20. This is a Class A product. In a domestic environment this product may cause radio interfer-
ence, in which case the user may be required to make corrective actions.
21. In order to prevent possible accidents due to a ground fault or a dielectric voltage, an ap-
propriate power plug should be installed by a person who has expertise in electricity. In
addition, the power plug should be connected to the receptacle which is properly grounded
without exceptions.
22. In order to prevent possible accidents due to a ground fault, the earth cable should be prop-
erly grounded.
23. For the control box to be connected to the LK-1900AN Series, use the exclusive control box
for the LK-1900AN Series. (If the control box for the LK-1900A Series is connected to the
LK-1900AN Series sewing machine, a malfunction can be caused.)

viii
Safety devices and warning labels
In addition, be aware that the safety devices such as the "eye protection cover" and
"finger guard" are sometimes omitted in the sketches, illustrations and figures in-
cluded in the engineer's manual for the explanation's sake. In the practical use, never
remove those safety devices.
Warning label
(Refer
to the
warning
label on
page i.)
The label gives
the minimum
precautions to
be taken when
operating the
sewing machine.
Warning label
against pinching
This label warns
that ngers or
other parts of
human body can
be pinched in
the thread take-
up lever.
Eye protection cover
This is a cover for
protecting eyes from
being injured by a
broken needle.
Finger guard
This is a cover for
preventing contact
between ngers and
the needle.
Thread take-up
lever cover
This is a cover
for preventing
contact between
the human body
and the thread
take-up lever.
Electrical-shock
danger label
(EU type)
(Refer to
"Elec-
trical-
shock
danger
label" on
page i.)
In order to
protect against
electrical shock,
safety precau-
tions to be
taken to avoid
danger are
written on this
label.
CAUTION
Motor cover
This is a cover for
preventing contact be-
tween the human body
and the motor.
Warning label
against pinching
This label warns
that hands can
be pinched un-
der the sewing
machine.
Power switch
This is a switch for discon-
necting the power unit of the
sewing machine from the
power supply.
Power switch (EU type)
This switch is used
for disconnecting
the power unit of
the sewing machine
from the power sup-
ply. It is also used
as the emergency
stop switch.
Selection of the power switch
Use the IEC60204-1-
compliant power switch with
rated current of 20 A or more
and short-circuit breaking
capacity of 120 A or more,
which has the operating sec-
tion in red against the yellow
background.

ix
CONTENTS
1. Specications ........................................................................................ 1
2. Conguration......................................................................................... 2
(1) Names of main unit.............................................................................................. 2
(2) Names and explanation of switches on the operation panel........................... 3
3. Standard adjustment............................................................................. 4
(1) Main shaft connection/disconnection................................................................ 4
(2) Adjustment of the main shaft wheel position ................................................... 6
(3) Removal of the main shaft motor and coupling................................................ 8
(4) Crank connecting rod connection/disconnection .......................................... 10
(5) Crank balancer positioning............................................................................... 12
(6) Lower shaft backlash adjustment and connection/disconnection ............... 12
(7) Oscillator gear positioning ............................................................................... 14
(8) Adjustment of hook oil amount ........................................................................ 14
(9) Shuttle connection/disconnection and oil wick piping .................................. 16
(10) Adjustment the height of the needle bar ......................................................... 16
(11) Hook adjustment................................................................................................ 18
(12)
Thread trimmer cam position adjustment and connection/disconnection .... 20
(13) Thread trimmer and presser foot origin sensor adjustment ......................... 20
(14) Adjustment of the height of the work clamp foot ........................................... 22
(15) Adjustment of the thread trimmer sensor ....................................................... 22
(16) Adjustment of the moving knife and counter knife position ......................... 24
(17) Adjustment of the height of the moving knife and counter knife.................. 24
(18) Inclination of the blade point of the counter knife.......................................... 26
(19) Floating amount of the thread tension disk .................................................... 26
(20) Second thread tension connection/disconnection......................................... 28
(21) AT unit connection/disconnection ................................................................... 30
(22) Position of the mechanical origin .................................................................... 32
(23) Adjustment of the Y origin sensor ...................................................................32
(24) Adjustment of the X origin sensor ................................................................... 34
(25) Adjustment of the wiper position ..................................................................... 34
(26) Adjustment of the wiper spring (LK-1903AN) ................................................. 36
(27) Adjustment of the position of the X feed motor and the Y feed motor
(Adjustment of the backlash of the driving gear) ........................................... 36
(28) Installing the feed plate support plate ............................................................. 38
(29) Installation of the feeder bar rear cover .......................................................... 38
(30) Adjustment of the bobbin winder driving wheel position.............................. 40
(31) Adjustment of the bobbin winder amount....................................................... 40
(32) Adjustment of the shuttle upper spring position............................................ 42
(33) Shuttle felt .......................................................................................................... 42
(34) Shape of the inner hook presser ...................................................................... 44
(35) Adjustment of the thread take-up spring......................................................... 44
(36) Needle thread clamp device connection/disconnection ................................ 46
(37) Adjustment of the needle thread clamp sensor.............................................. 48
(38) Adjustment of the needle thread clamp notch................................................ 50

x
4. Sub-class information......................................................................... 52
(1) Models classied by button sizes (LK-1903AN) ............................................. 52
(2) Table of Standard Patterns (LK-1903AN).........................................................53
5. Memory switches................................................................................. 54
(1) Memory switch start and change ..................................................................... 54
(2) Table of memory switch functions ................................................................... 55
6. Test mode............................................................................................. 59
(1) Test mode start................................................................................................... 59
(2) Display output test............................................................................................. 60
(3) Method of conrmation according to each test program No. ....................... 61
7. Miscellaneous...................................................................................... 66
(1) Various printed wiring boards .......................................................................... 66
(2) LK-1900 data ROM ............................................................................................. 73
(3) Dipswitch setting ............................................................................................... 73
(4) Table of standard pattern specications ......................................................... 74
(5) Table of standard patterns ................................................................................ 75
8. Optional features................................................................................. 77
(1) Connection of PK-57.......................................................................................... 77
(2) Table of optional parts....................................................................................... 78
(3) Table of the work clamp foot............................................................................. 80
9. Maintenance......................................................................................... 82
(1) Replacing the fuse ............................................................................................. 82
(2) 100V ←→ 200V voltage specication changeover.......................................... 82
(3) Greasing parts.................................................................................................... 83
(4) Parts to which grease is applied ...................................................................... 84
(5) Grease-up procedures for the specied position........................................... 91
10. Error list............................................................................................... 92
11. Troubles and corrective measures .................................................... 95
(1) Mechanical parts................................................................................................ 95
(2) Sewing conditions ............................................................................................. 97
(3) Electrical components..................................................................................... 106
12. Circuit diagrams .................................................................................117
(1) Block diagram A............................................................................................... 117
(2) Power supply circuit diagram A...................................................................... 118
(3) Power supply circuit diagram B ..................................................................... 119
(4) Power supply circuit diagram C ..................................................................... 120
(5) Servo motor circuit diagram ...........................................................................121
(6) Sensor ·pedal VR circuit diagram.................................................................. 122
(7) MAIN ·PANEL board circuit diagram ............................................................. 123
(8) Motor ·solenoid circuit diagram .................................................................... 124
13. Table drawings................................................................................... 125
(1) Table type for longitudinal Installation .......................................................... 125
(2) Table type for lateral Installation .................................................................... 126

– 1 –
1. Specications
No. Model name
Item
Application
LK-1900AN LK-1901AN LK-1902AN LK-1903AN
1 Application Bartacking Eyelet buttonhole
bartacking
Belt-loop attaching Lock stitch button sewing
2 Sewing area X-Direction (right, left) 40 mm;
Y-Direction (forward, backward) 30 mm
—————
3 Button size ————— Type: Round-shaped, at
button
Size: ø8 to ø32 mm,
Standard (ø8 to ø20 mm)
4Max. sewing speed * 3,200 sti/min max.
(*2,700 sti/min fo
the 2-fold semi-
rotary hook)
* 3,000 sti/min max.
(When sewing pitches are less than
5 mm in X-direction and 3.5 mm in
Y-direction)
* 2,700 sti/min max.
5 Stitch length 0.1 mm to 10.0 mm (adjustable in 0.1 mm step)
6 Feed motion of work clamp
foot
Intermittent feed (2-shaft drive by stepping motor)
7 Needle bar stroke 41.2 mm 45.7 mm
8 Needle DP×5 #14 DP×17 #14
DP×5 #11 (F, M)
(DP×17 #21 heavy-
weight material)
(DP×17 #21 heavy-
weight material)
9 Work clamp lifting system Pulse motor
10 Lifting (lift) amount of work-
clamp foot
Standard 14 mm, Max. 17 mm
(In the reverse-rotation needle-up function)
Max. 13 mm
11 Number of standard
patterns
50 patterns 3 patterns 6 patterns 50 patterns
12 Wiper system Interlockly with work clamp foot lifter by pulse motor
13 Needle thread clamp device Standard: General 0 Standard: Disable 1
(Caution) 1.
14 Needle thread tension Active tension (electronic thread tension control mechanism)
15 Hook Standard semi-
rotary hook
(2-fold semi-rotary
hook)
Standard semi-rotary hook
16 Lubrication Hook: minute-quantity lubrication
17 Lubricating oil JUKI NEW Defrix oil No.2 (equivalent to ISO VG32) (Lubrication system)
18 Grease 1. Penetration No. 2 lithium grease, 2. Templex N2, 3. JUKI Grease A, 4. JUKI Grease B
(Caution) 2.
19 Memory medium EEP-ROM (128 Kbyte) EP-ROM (32 Kbyte)
20 Number of stitches that can
be stored in memory
Max. 20,000 stitches
21 Enlarging/Reducing facility X-Direction, Y-Direction: 20 to 200% each (1% step)
22 Enlarging/Reducing method Pattern enlargement/reduction can be done by increasing/decreasing the stitch length
23 Sewing speed limits 400 to 3,200 sti/min (100 sti/min step)
(2,700 sti/min max. for the 2-fold semi-rotary hook)
400 to 2,700 sti/min
(100 sti/min step)
24 Material clawing amount ————— Max. 3 mm ————— —————
25 Pattern selector facility Pattern No. designation system (1 to 200)
26 Bobbin thread counter Up/Down method (0 to 9999)
27 Sewing machine motor 450W compact AC servomotor (direct-drive system)
28 External dimensions W: 1,200 mm, L: 660 mm, H: 1,100 mm (standard table stand applied)
29 Weight Machine head (include motor): 42 kg, Control box: 16.5 kg
30 Power consumption 320W
31 Working temperature range 5℃ to 35℃
32 Working humidity range 35% to 85% (no dew condensation permissible)
33 Power-supply voltage Single-phase 100V · 3-phase 200V , Rated voltage ±10% , 50/60Hz
* Maximum sewing speed should be reduced according to the sewing conditions.
(Caution) 1. LK-1903AN is set to needle thread clamp prohibited (no motion) with memory switch
No. 35 at the time of standard delivery.
2. Grease type, refer to "(3) Greasing parts of [9] Maintenance".

– 2 –
2. Conguration
(1) Names of main unit
 1 Sewing machine head
 2 Work clamp foot
 3 Thread stand
 4 Operation panel
 5 Power switch
 6 Control box
 7 Pedal switch
 8 Power switch (EU Type)
1
2
3
4
5
6
7
8

– 3 –
8Item selection LED
LEDs of the selected items light up.
Pattern No. X scale Y scale
Max. speed
limitation
Sewing counter Bobbin winder
Work clamp
foot lowering
Thread tension
9Needle thread clamp ON/OFF key
This key selects effective/ineffective of needle
thread clamp. When it is effective, needle thread
clamp disply LED lights up. (Note) 1.
!0 Needle thread clamp display LED
When this LED lights up, needle threas clamp
operaters.
!1 Pattern registration key
This key registers the pattern. When this key is
pressed, the pattern registered here can sew
immediately. X/Y scale, sewing position, etc.
can be changed and registered.
1“Ready” key
This key changes over the setting state from
the panel to the sewing state where the sewing
machine actually operates.
2Sewing LED
This LED goes off at the time of setting state and
lights up at the time of sewing state. Change-
over can be performed with “Ready” key.
3“Reset” key
This key is used for canceling error or returning
the set value to the initial value.
4“Mode” key
This key makes the setting mode of the memory
switch.
5“+ / Feed forward” key, and “- / Feed back-
ward” key
This key is used for changing pattern No. and
X/Y scale, and feed forward/feed backward.
6“Selection” key
This LED indicates the set values of the selected
items such as pattern No., X/Y scale, etc.
7Data indication LED
This LED indicates the set values of the selected
items such as pattern No., X/Y scale, etc.
(Note) 1. LK-1903AN is set to needle thread clamp prohibited (no motion) with memory switch No.
35 at the time of standard delivery.
1
2
5
43
6
7
8
9
!0
!1
(2) Names and explanation of switches on the operation panel

– 4 –
3. Standard adjustment
(1) Main shaft connection/disconnection
Procedures of disassembling
1. Loosen the set screw 2of the main shaft counterbalance 1through the screwdriver hole A, then
remove the taper screw 3.
2. Loosen the two set screws 4(through the screwdriver hole B), and also the two each of 5and 6.
At that time, loosen the second set screw rst. The rst set screw should be removed completely from
the at part of the main shaft 7.
3. Remove the main shaft motor 8.
Refer to "(3) Removal of the main shaft motor and coupling."
4. Loosen the two set screws !0.
Pay attention to possible injury at that time because the balancer !1 begins to turn when the set
screw !0 is loosened.
5. Loosen the two set screws !2.
At that time, the rst set screw of the set screw !2 should be removed completely from the at part of
the main shaft 7.
6. Loosen the two set screws !3, the two set screws !4 and the two set screws @2.
7. Draw out the main shaft 7in the direction of the Arrow C.
Main shaft taper hole
Screwdriver hole B Screwdriver hole A
No. 2 screw
No. 1 screw
No. 2 screw
No. 2 screw
No. 1 screw
No. 1 screw

– 5 –
Procedures of assembling
1. Insert the crank rod !5, balancer !1, the main shaft wheel @1, hand pulley gear A !6, bobbin winder
driver wheel !7, and the main shaft counterbalance 1in the main shaft 7in this order, and mount
the assembly on the frame.
2. Insert the taper screw 3in the taper hole of the main shaft, and tighten it. Then, tighten the set screw
2 to x the main shaft counterbalance 1.
3. Lightly press the main shaft counterbalance 1in the direction of the arrow D and also the middle
metal !8 in the direction of the arrow E. Then, tighten the two set screws 5.
(Tighten the rst screw so that it touches atly on the main shaft 7. Then, tighten the second one.
Same procedures followed hereafter.)
4. Tighten the two each set screws 4and 6, respectively.
(Make sure that the rst screw touches atly on the main shaft 7.)
5. Push the hand pulley @0 in the direction of the arrow F so that the hand pulley gear A !6 is meshed
with that the hand pulley gear B !9. In this state, x the pulley with the two set screws !4.
6. Mount the main shaft motor 8and the coupling 9.
Refer to "(3) Removal of the main shaft motor and coupling."
7. Fix the crank rod !5 with the two set screws !2.
Refer to "(4) Crank connecting rod connection/disconnection."
8. Fix the balancer !1 with the two set screws !2.
Refer to "(5) Crank balancer positioning."
9. Fix the bobbin winder driver wheel !7 with the two set screws !3.
Refer to "(30) Adjustment of the bobbin winder driving wheel position."
10. Fix the main shaft wheel @1 with the two set screws @2.
Refer to "(2) Adjustment of the main shaft wheel position."
* Try to turn the main shaft 7 and conrm that there is no torque.

– 6 –
(2) Adjustment of the main shaft wheel position
Standard adjustment
The distance is 3 mm between the measuring plane Aof the main shaft wheel 1and the plane Bof the
middle bearing bush of the main shaft.
3mm
1
2
A
B

– 7 –
Adjustment procedures Results of Improper adjustment
1. Adjust the position of the main shaft wheel 1 and x it with two
set screws 2.

– 8 –
(3) Removal of the main shaft motor and coupling
Procedures of disassembling
1. Removal of the main shaft motor together with coupling
Loosen the two set screws 5on the main shaft side of the coupling 2. Then, remove the four motor
set screws 4.
2. To remove the coupling 2from the main shaft motor 3, loosen the two set screws 6on the main
shaft side.
(Caution) Turn the main shaft 1in the direction of forward rotation A. The screw (hole) that can
be seen rst is the No. 1 screw. Loosen the screws, starting with the No. 2 screw. Tight-
ening should be done, starting with the No. 1 screw.
No. 1 screw
No. 2 screw
No. 1 screw
Flat section
Cord
0.5 mm