Alfa Network A1920 User manual

INSTRUCTION MANUAL
High speed direct-drive computerized
lockstitch sewing machine
MODEL A1920

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IMPORTANT SAFETY INSTRUCTIONS
1. Observe the basic safety measures, including, but not limited to the following ones,whenever you
use the machine.
2. Readallthe instructions, including, but notlimited to this instructionmanual before youuse the
machine. Inaddition, keep this instructionmanual so that you may read it allanytimewhen
necessary.
3. Use the machine after it hasbeen ascertained that conforms with safetyrules/standards valid in
your Country.
4. All safety devices must be in positionwhen the machineis readyfor work or in operation. The
operation without the specified safety devices isnot allowed.
5. This machine shallbe operated by appropriately-trained operators.
6. For your personal protection, we recommend that you wear safety glasses.
7. For the following,turnoffthepowerswitchor disconnect the power plug of the machine from the
receptacle,
7.1. For threading needle(s), looper, spreader, etc. And replacing bobbin.
7.2. For replacingpart(s)of needle, presser foot,throatplate, looper, spreader, feeddog,
needle guard, folder, cloth guide etc.
7.3. For repair work.
7.4. When leaving the working place or when the working place is unattended.
8. If you shouldallow oil, grease, etc. used withthe machineand devicesto comein contactwithyour
eyesor skin or swallow any of suchliquid by mistake, immediately wash thecontacted areas and
consult a medical doctor.
9. Tampering with the live parts and devices, regardless of whether the machine is powered, is
prohibited.
10. Repair, remodeling and adjustment works must only be done by appropriately trained
technicians or specially skilled personnel. Only spare parts designated by can be used for
repairs
11. General maintenance and inspection works have to be done by appropriately trained
personnel.
12. Repair and maintenance works of electrical components shall be conducted by qualified
electric technicians or under the audit and guidance of specially skilled personnel. Whenever
you find a failure of any of electrical components, immediately stop the machine.
13. Beforemaking repair and maintenance works on the machine equipped with pneumatic partssuch
as an air cylinder, the air compressor has to be detached from the machine and the compressed air
supply has to be cut off. Existing residualair pressure alter disconnecting the air compressorfrom
themachine has to be expelled. Exceptions tothis are only adjustments and performance checks
done by appropriately trained technicians or specially skilled personnel.
14. Periodically clean the machine throughout the period of use.
15. Grounding the machine is always necessaryfor the normaloperation of the machine.The machine
has to be operated in an environment that is free from strong noise sources such as high-frequency
welder.
To get the mostout of the many functions of this machine and operate it in safety, it is necessary to
use this machine correctly. Please read this instruction manual carefully before use. We hope you will
enjoythe use of your machine fora long time. Please remember to keep this manual in asafeplace.

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16. An appropriate power plug has to be attached to the machine by electric technicians. Power plug
has to be connected to a grounded receptacle.
17. Remove ormodify the machine in accordance with the safely rules/standards while takingallthe
effective safety measures, assumes no responsibility for damage by remodeling or modification of
the machine.
18. Warning hints are marked with the two shown symbols.
Danger of injury to operator or service staff
Items requiring special attention

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DANGER
FOR SAFE OPPERATION
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.
CAUTION
1. To avoid personal injury, never operate the machine with any of the belt cover, Finger guard or
safety devices removed.
2. To prevent possible personal injuries caused by being caught in the machine, keep your fingers,
head and clothes away from the hand wheel, V belt and the motor while the machine is operation.
In addition, place nothing around them.
3. To avoid personal injury, never put your hand under the needle when you turn "ON" the power
switch or operate the machine.
4. To avoid personal injury, never put your fingers into the thread take-up cover while the machine is
in operation.
5. The hook rotates at a high speed while the machine is in operation. To prevent possible injury to
hands, be sure to beep your hands away from the vicinity of the hook during operation. In
addition, be sure to turn OFF the power to the machine when replacing the bobbin.
6. To avoid possible personal injuries, careful not to allow your fingers in the machine when
tilting/raising the machine head.
7. To avoid possible accidents because of abrupt start of the machine, turn OFF the power to the
machine when tilting the machine head.
8. lf your machine is equipped with a servo-motor, the motor does not produce noise while the
machine is al rest. To avoid possible accidents due to abrupt start of the machine, be sure to turn
OFF the power to the machine.
9. To avoid electrical shock hazards, never operate the sewing machine with the ground wire for the
power supply removed.
10. To prevent possible accidents because of electric shock or damaged electrical components(s),
turn OFF the power switch in prior to the connection/disconnection of the power plug.
CAUTION: To avoid malfunction and damage of the machine, confirm the following.
• Before you put the machine into operation for the first time afterthe setup, cleanit
thoroughly.
• Remove all dust gathering during transportation and oil it well.
• Confirm that thepowerplug has beenproperly connected to the power supply.
• Neveruse the machine in the statewhere the voltage type is different from the
designatedone.
• The direction of rotation of the sewing machine is counterclockwise as observed from the
hand wheelside.Be careful not to rotate it in reverse direction.
BEFORE OPERATION

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INDEX
1. SPECIFICATIONS.........................................................................................................................................1
2. INSTALLATION............................................................................................................................................1
3. ADJUSTING THE HEIGHT OF THE KNEE LIFTER...........................................................................................2
4. INSTALLING THE THREAD STAND...............................................................................................................2
5. LIPIN...........................................................................................................................................................2
6. LUBRICATION.............................................................................................................................................3
7. ADJUSTING AMOUNT OF OIL (OIL SPLASHES) IN THE HOOK .....................................................................3
8. ATTACHING THE NEEDLE ...........................................................................................................................4
9. SETTING THE BOBBIN INTO THE BOBBIN CASE..........................................................................................5
10. ADJUSTING THE STITCH LENGTH ...............................................................................................................5
11. PRESSER FOOT PRESSURE..........................................................................................................................5
12. HAND LIFTER..............................................................................................................................................5
13. ADJUSTING THE HEIGHT OF THE PRESSER BAR .........................................................................................6
14. THREADING THE MACHINE HEAD..............................................................................................................6
15. THREAD TENSION ......................................................................................................................................6
16. THREAD TAKE-UP SPRING..........................................................................................................................7
17. ADJUSTING THE THREAD TAKE-UP STROKE...............................................................................................7
18. NEEDLE-TO-HOOK RELATIONSHIP .............................................................................................................7
19. HEIGHT OF THE FEED DOG.........................................................................................................................8
20. TILT OF THE FEED DOG ..............................................................................................................................9
21. ADJUSTING THE FEED TIMING ...................................................................................................................9
22. ADJUSTING THE NEEDLE STOP POSITION ................................................................................................10
23. PEDAL PRESSURE AND PEDAL STROKE ....................................................................................................11
24. ADJUSTMENT OF PEDAL ..........................................................................................................................11
25. PEDAL OPERATION ..................................................................................................................................12
26. ONE-TOUCH TYPE REVERSE FEED STITCHING MECHANISM....................................................................12

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1. SPECIFICATIONS
Medium-weight model
Light-weight model
Heavy-weight model
Application
General fabrics, light-
weightandmedium-
weight materials.
General fabrics, fight-
weight materials.
Medium-weight materials,
heavy-weight materials.
Sewing speed
Max. 4500 rpm
Max. 4000 rpm
Max. 3500 rpm
Max. stitch length
4 mm
5 mm
Needle
08 x 1 #9-#11
DA x 1 #9-#11
D8 x 1 #20-#23
Presser for lift
10 mm (standard)
13 mm (Max.)
9 mm (Max.)
10 mm (standard)
13 mm (Max.)
Lubricating oil
Defrix Oil NO.10
2. INSTALLATION
(1) Installing theunder cover
1) Theoil pan should reston the four corners of the machine table groove.
2) Fix two rubber seats 1 on side A (operator's side) using nails 2 as illustrated above. Fix two cushion seats 3 on
side B (hinged side) using a rubber-based adhesive. Then place oil pan 4 on the fixed seats.
3) Fit hinge 1 into the opening in the machine bed, and fit the machine head to table rubber hinge 2 before placing
the machine head on cushions 3 on the four corners.

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3. ADJUSTING THE HEIGHT OF THE KNEE LIFTER
•
1) The standard height on the presser footlifted using the knee filler is 10 mm.
2) You can adjust the presser foot lift upto 13mmusing knee lifter adjust screw 1 (Max.9 mm for A type)
3) When you have adjusted the presser foot 11ft to over 1Omm, be surethat the bottom end of needlebar
2 in its lowest position does not hit presser foot 3.
4. INSTALLING THE THREAD STAND
1) Assemble the thread stand unit; insert it into the
hole of machine table.
2) Tighten locknut 1 to fix the thread stand.
3) For ceiling wring, pass the power cord through
spool rest rod 2.
5. LIPIN
1) Please firstly disassemble the small screw of the thread take-up crank shaft
1, then fulfill the take-up crank shaft 1 with lubricating grease.
2) Please, firstly disassemble the needle rod holder ASM, then take off the small
screw on the connection rod 2. Lastly, fulfill the needle bar connection ASM 2
with lubricating grease.
IMAGEN
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.
WARNING
Tum OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.

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6. LUBRICATION
Information on lubrication
1) Fill oil pan 1 with Machine Oil up to HIGH mark A.
2) When the oil level lowers below LOW mark B, refill the oil
pan with the specified oil.
3) When you operate the machine alter lubrication, you will
see splashing oil through oil sight window 2 if the lubrication
is adequate.
4) Note that the amount of the splashing oil is unrelated to the
amount of the lubricating oil.
Adjusting the amount of oil supplied to the
face plate parts
1) Adjust the amount of oil supplied to the thread take up and
needle bar crank 2 by turning adjust pin 1.
2) The minimum amount of oil is reached when marker dot A
is brought close to needle bar crank 2 by turning the adjust pin
in direction B.
3) The maximum amount of oil is reached when marker dot
A is brought to the position just opposite from the needle
bar crank by turning the adjust pin in direction C.
7. ADJUSTING AMOUNT OF OIL (OIL SPLASHES) IN THE HOOK
1. Amount of oil (oil splashes) confirmation paper 2. Position to confirm the amount of oil (oil splashes)
Oil splashes confirmation paper Closely fit the paper against
the wall surface of the bed
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.
When you first operate your machine after setup or after an extended period of disuse, run your
machine at 3,000 to 3,500 rpm. for about 10 minutes for the purpose of break-in.
WARNING
Be extremely careful about the operation of the machine since the amount of oil has to be
checked by turning the hook at a high speed.

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* When carrying out the procedure described below in 2, remove the slide plate and take extreme caution notto
allow your fingers to come in contact with the hook.
1) lf the machine has not been sufficiently warmed up for operation, make the machine run idle for
approximately three minutes (moderate intermittent operation).
2) Placetheamountofoil (oilsplashes)confirmation paperunder the hook while the sewingmachineisin
operation.
3) Confirm the height of the oil surface in the oil reservoir is within the range between "HIGH" and "LOW".
4) Confirmation of the amount of oil should be completed in five seconds. (Check the period of time with a watch)
• Sample showing the appropriate amount of oil
1) The amount of oil shown in the samples on the left should be finely
adjusted in accordance with sewing processes. Be careful not to
excessively increase/decrease the amount of oil in the hook. lf the
amount of oil is too small, the hook will be seized (the hook will be
hot). If the amount of oil is too much, the sewing product may be
stained with oil.
2) Adjust the amount of oil in the hook so that the oil amount (oil
splashes) should not change while checking the oil amount three
times (on the three sheets of paper).
• Adjusting the amount of oil
1) Turning the oil amount adjustment screw attached on the hook
driving shaft front bushing in the “+” direction (in direction A), will
increase the amount of oil (oil spots) in the hook. In contrary, in the “-“
direction (in direction B), will decrease it.
2) After the amount of oil in the hook has been property adjusted with
the oil amount adjustment screw, make the sewing machine run idle
for approximately 30 seconds to check the amount of oil in the hook.
8. ATTACHING THE NEEDLE
WARNING / ADVERTENCIA
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.
Splashes of oil from the hook
Appropriate amount of oil (small)
Appropriate amount of oil (large)

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9. SETTING THE BOBBIN INTO THE BOBBIN CASE
1) Pass the thread through thread slit A, and pull the thread direction B.
By so doing, the thread will pass under the tension spring and come
out from notch.
2) Check that the bobbin rotates in the direction of the arrow when
thread C is pulled.
10. ADJUSTING THE STITCH LENGTH
11. PRESSER FOOT PRESSURE
12. HAND LIFTER

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13. ADJUSTING THE HEIGHT OF THE PRESSER BAR
1) Loosen setscrew 1 and adjust the presser bar height or the angle of
the presser foot
2) After adjustment, securely lighten the setscrew 1.
14. THREADING THE MACHINE HEAD
15. THREAD TENSION
(1) Adjusting the needle thread tension
1) As you turn thread tension No.1 nut 1 clockwise (in
direction A), the thread remaining on the needle
after thread trimming will be shorter.
2) As you turn nut 1 counterclockwise (in direction B),
the thread length will be longer.
3) As you turn thread tension No.2 nut 2 clockwise (in
direction C), the needle thread tension will be
increased.
4) As you turn nut 2 counterclockwise (in direction D),
the needle thread tension will be decreased.
(2) Adjusting the bobbin thread tension
1) As you turn tension adjust screw 3 clockwise (in
direction E), the bobbin thread tension will be
increased.
2) As you turn screw 3 counterclockwise (in direction
F), the bobbin thread tension will be decreased.
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.

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16. THREAD TAKE-UP SPRING
(1) Changing the stroke of thread take-up spring 1.
1) Loosen setscrew 2.
2) As you turn tension post 3 clockwise (in direction A),
the stroke of the thread take-up spring will be
increased.
3) As you turn the knob counterclockwise (in direction B),
the stroke will be decreased.
(2) Changing the pressure of thread take-up spring
1.
1) Loosen setscrew 2, and remove thread tension (asm)
5.
2) Loosen setscrew 4.
3) As you turn tension post 3 clockwise (in direction A),
the pressure will be increased.
4) As you turn the post 3 counterclockwise (in direction
B), the pressure will be decreased.
17. ADJUSTING THE THREAD TAKE-UP STROKE
1) When sewing heavy-weight materials, move thread guide 1
to the left (in direction A) to increase the length of thread
pulled out by the thread take-up.
2) When sewing lights-weight materials, move thread guide 1 to
the right (in direction B) to decrease the length of thread
pulled out by the thread take-up.
3) Normally, thread guide 1 is positioned in a way that marker
line C is aligned with the center of the crew.
18. NEEDLE-TO-HOOK RELATIONSHIP
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.
WARNING
To avoid possible personal injury due to abrupt start of the machine, turn off the power to the
machine and check to be sure that the motor has totally stopped rotating in prior.

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Adjust the timing between the needle and the hook as follows:
1) Turn the hand wheel to bright the needle bar down to the lowest point of its stroke, loosen setscrew 1, (adjusting the
needle bar height)
(Adjusting the needle bar height)
2) (For a DB needle) Align marker line A on needle bar 2 with the bottom end of needle bar lower bushing 3, then tighten
setscrew 1.
(For a DA needle) Align marker line C on needle bar 2 with the bottom end of needle bar lower bushing 3, then tighten
setscrew 1.
(Adjusting position of the hook a)
3) (For a DB needle) Loosen the three hook setscrews, turn the hand wheel and align marker line B on ascending needle
bar with the bottom end of needle bar lower bushing 3.
(For a DA needle) Loosen the three hook setscrews, turn the hand wheel and align marker line D on ascending needle
bar with the bottom end of needle bar lower bushing 3.
4) After making the adjustments mentioned in the above steps, align hook blade point 5 with the centre of needle 4.
Provide a clearance of 0.04 mm to 0.1 mm (reference value) between the needle and the hook then securely tighten
setscrews in the hook.
19. HEIGHT OF THE FEED DOG
1) Loosen screw 2 of crank 1.
2) Move the feed bar up or down to make adjustment.
3) Securely lighten screw 2.
If the clearance between the blade point of hook and the needle is smaller than the specified value,
the blade point of hook will be damaged. If the clearance is larger, stitch skipping will result.
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.

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20. TILT OF THE FEED DOG
a front up
b standard
c front down
d throat plate
1) The standard tilt (horizontal) of the feed dog is obtained when marker dot A on the feed bar shaft is aligned with
marker dot B on feed rocker C. (The marker dot B inclines forward the feed rocker shaft by 90º, as standard)
2) To tilt the feed dog with its front up in order to prevent puckering, loosen the setscrew, and turn the feed bar shaft
90º in the direction of the arrow, using a screwdriver.
3) To tilt the feed dog with its front down in order to prevent uneven material feed, turn the feed bar shaft in the opposite
direction from the arrow. (The standard tilt for).
21. ADJUSTING THE FEED TIMING
Standard feed timing
Advanced feed timing
Delayed feed timing
1) Loosen screws 2 and 3 in feed eccentric cam 1, move the feed eccentric cam in the direction of the arrow or
opposite direction of the arrow, and firmly tighten the screws.
2) For the standard adjustment, adjust so that the top surface of feed dog and the top end of needle eyelet are flush
with the top surface of throat plate when the feed dog descends below the throat plate.
3) To advance the feed timing in order to prevent uneven material feed, move the feed eccentric cam in the direction of the
arrow.
4) To delay the feed timing in order to increase stitch tightness, move the feed eccentric cam in the opposite, direction from
the arrow.
Be careful not to move the feed eccentric cam too far, or else needle breakage may result.
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.
WARNING
To avoid possible personal injury due to abrupt start of the machine, turn off the power to the
machine and check to be sure that the motor has totally stopped rotating in prior.
Whenever the feed dog tilt is adjusted, the feed dog height will be changed. So it is necessary to
check the height after tilt adjustment.

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22. ADJUSTING THE NEEDLE STOP POSITION
General principle:
The head is calibrated to thread take-up lever
1) Turn on power button, enter work mode;
2) Press the “F” key for 2 seconds, the standard nose
interface, the thread take-up to the position which is
far from the highest position 1.5 –2 mm;
3) Press “S” key to save the head position, the system
automatically return to the working interface, buzzer
look; nose calibration is complete.
Operation panel
Note: If you mistakenly entered the head of the table interface press the “F” key to return to.
Schematic diagram of thread take-up lever
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.

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23. PEDAL PRESSURE AND PEDAL STROKE
(1) Adjusting the pressure required to depress the
front part of pedal.
1) This pressure can be changed by changing the mounting
position of pedaling pressure adjust spring 1.
2) The pressure decreases when you hook the spring on the
left side.
3) The pressure increases when you hook the spring on the
right side.
(2) Adjusting the pressure required to depress the
back part of the pedal
1) This pressure can be adjusted using regulator screw 2.
2) The pressure increases as you turn the regulator screw in.
3) The pressure decreases as you turn the screw out.
(3) Adjusting the pedal stroke
1) The pedal stroke increases when you insert connecting
rod 3 into the right hole.
24. ADJUSTMENT OF PEDAL
(1) Installing the connecting rod
1) Move pedal 3 to the right or left as illustrated by the
arrow so that motor control lever 1 and connecting
rod 2 are straightened.
(2) Adjusting the pedal angle
1) The pedal tilt can be freely adjusted by changing the length
of the connecting rod.
2) Loosen adjust screw 4, and adjust the length of connecting
rod 5.
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.
.
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.

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25. PEDAL OPERATION
(1) The pedal is operated in the following four
steps:
1) The machine runs at low sewing speed when you lightly
depress the front part of the pedal. B
2) The machine runs at high sewing speed when you
further depress the front part of the pedal. A
(lf the automatic reverse feed stitching has been preset,
the machine runs at high speed alter it completes
reverse feed stitching)
3) The machine stops (with its needle up or down) when
you reset the pedal to its original position.
4) The machine trims threads when you fully depress the
back part of the pedal. C
* lf your machine is provided with the Auto-lifter an
addition steps is given between the machine stop and
thread trimming step. The presser foot goes up when
you lightly depress the back part of the pedal D, and if
you further depress the back part, the thread trimmer is
actuated.
26. ONE-TOUCH TYPE REVERSE FEED STITCHING MECHANISM
(1) How to operate
1) The moment button 1 is pressed, the machine performs
reverse feed stitching.
2) The machine performs reverse feed stitching as long as
the button is held pressed.
3) The machine resumes normal feed stitching the moment
the button is released.
4) The machine runs at high sewing speed when you
further depress the front part of the pedal.
(1) How to operate the LED light
1) Push the button 2, LED light be bright.
2) Pull the button 2, LED light be power off.
WARNING
Turn OFF the power before starting the work so as to prevent accidents caused by abrupt start
of the sewing machine.