JUKI LK-1900AN User Manual

– 41 –
Adjustment procedures Results of Improper adjustment
1. Adjust the position of the bobbin winder driving wheel
1
and
x it with two setscrews
2
.
o
If the distance of 10 mm is insuf-
cient, rubber ring wear may
occur in the bobbin winder unit.
In addition, the bearing life may
be reduced in the bobbin winder
unit.
o
If the distance of 10 mm is ex-
cessive, normal thread winding
may fail. In addition, this will also
cause rubber ring slippage in the
bobbin winder unit and give rise
to wear.
Adjustment procedures Results of Improper adjustment
1. Loosen the setscrew
3
of the bobbin winder lever and adjust
the distance to 14 mm between the bobbin winder lever
1
and
the bobbin winder shaft
2
. After that, tighten the setscrew
3
of
the bobbin winder lever.
2. Start the sewing machine and wind the thread at the bobbin
winder. Conrm the amount of winding.
1) If the amount of winding seems to be too much, adjust the
bobbin winder lever
1
in the direction of the arrow
A
.
2) If the amount of winding seems to be too less, adjust the
bobbin winder lever
1
in the direction of the arrow
B
.
3. If the winding state of the thread
7
around the bobbin
8
seems to be uneven, loosen the nut
5
and adjust the height of
the thread tension control
4
.
(Example) If the amount of the wound thread is less on the
upper side of the bobbin
8
as illustrated, adjust the
thread tension control
4
upwards.
o
If too much thread is wound
(thread protruded from the bob-
bin
8
), the thread
7
will come
in contact with the inside of the
bobbin case and this can be a
cause of sewing deciency.
o
If the amount of thread winding
is uneven at top and bottom of
the bobbin
8
, stitch perforation
may become irregular.

JUKI LK-1900AN Specifications

General

Stitch Type	Lockstitch
Motor Power	550 W
Type	Lockstitch sewing machine
Stitch Length	Max. 5mm
Needle Type	DPx5
Hook	Full rotary hook
Presser Foot Lift	13 mm

Summary

Safe Use Guidelines and Risk Identification

Explanation of Risk Levels

Defines DANGER, WARNING, CAUTION levels for risk indications.

Pictorial Warning Indications and Labels

Explains various warning labels and pictorial indications used in the manual.

Comprehensive Safety Precautions

General Safety, Device, and Training Precautions

Covers basic precautions, safety devices, application limits, and operator training.

Operational Stage Safety: Power Off and Transportation

Operational Safety Procedures

Unpacking, Installation, and Pre-Operation Checks

Safe Operation During Use

Guidelines for safe practices while the machine is operating.

Maintenance and Environmental Considerations

Precautions for Specific Maintenance Stages

Electrical Components Safety: Transportation and Replacement

Safety in Adjustment and Disassembly/Assembly

General Safe Operation Guidelines for LK-1900AN Series

Identification of Safety Devices and Warning Labels

3. Standard Adjustment Procedures: Mechanical Components

Main Shaft and Motor Adjustments

Covers main shaft connection, wheel position, motor, and coupling adjustments.

Crank, Shaft, and Oscillator Adjustments

Details adjustments for crank rod, balancer, lower shaft, oscillator, and hook oil.

Trimmer, Sensor, and Knife Adjustments

Covers adjustments for shuttle, needle bar, hook, trimmer, sensors, knives, tension, and AT unit.

Feed, Origin, and Motor/Wiper Adjustments

Adjustments for mechanical origin, sensors, motors, and wiper systems.

Winding, Clamp, and Spring Adjustments

Covers bobbin winder, shuttle spring, felt, hook presser, take-up spring, and needle clamp.

Needle Thread Clamp Device Connection/Disconnection

Procedures for disassembling the needle thread clamp device.

Needle Thread Clamp Sensor Adjustment

Standard adjustment for the needle thread clamp sensor.

Needle Thread Clamp Notch Adjustment

Standard adjustment for needle thread clamp notch R and F positions.

5. Memory Switch Settings

Memory Switch Start and Change Procedure

Table of Memory Switch Functions

6. Test Mode Operations

Initiating Test Mode

Instructions on how to start and select test modes on the machine.

Confirming Test Program Inputs and States

Test Programs CP-2 and CP-3 Usage

Test Programs CP-4 and CP-5 Usage

Test Programs CP-6 and CP-7 Usage

Test Program CP-8 Software Version Display

9. Maintenance Procedures

Fuse Replacement and Voltage Changeover

Recommended Greases and Application Areas

Greasing Points: Presser Bar Lifter and Wiper Areas

Greasing Points: Thread Tension and Trimmer Areas

Greasing Points: Feed and Motor/Main Shaft Areas

Greasing Points: Lower Shaft Area

Greasing Points: Needle Thread Clamp Mechanism Area

Greasing Points: LK-1901AN Related Parts

Greasing Points: LK-1903AN Related Parts

9. Maintenance Procedures

Grease-Up Procedures for Specified Positions

Details procedures for greasing specific positions, including error code E220/E221.

10. Error List and Corrective Actions

11. Troubles and Corrective Measures: Mechanical Issues

Mechanical Part Troubles and Solutions

Lists mechanical troubles, their causes, and corrective measures.

11. Troubles and Corrective Measures: Sewing Condition Issues

Sewing Condition Troubles and Solutions

Covers issues with sewing conditions, thread breakage, trimming, and stitch quality.

11. Troubles and Corrective Measures: Thread Issues

Thread Breakage Troubles and Solutions

Lists troubles related to thread breakage, causes, and corrective measures.

Defective Thread Trimming and Solutions

Lists troubles related to defective thread trimming, causes, and corrective measures.

11. Troubles and Corrective Measures: Stitch Quality Issues

Poorly Tense Stitches and Solutions

Lists troubles related to poorly tense stitches, causes, and corrective measures.

11. Troubles and Corrective Measures: Synthetic Thread Issues

Synthetic Thread Stitch Defects and Solutions

Lists troubles related to synthetic thread stitches, causes, and corrective measures.

11. Troubles and Corrective Measures: Electrical Issues

Electrical Component Troubles and Solutions

Lists electrical component troubles, causes, and corrective measures.

Electrical Component Troubles and Solutions (cont.)

Continues listing electrical component troubles, causes, and corrective measures.