Alfa Network A1940 User manual

MANUAL DE INSTRUCCIONES
Programmable industrial straight stitch machine
with thread trimmer and presser foot lifter
MODELO A1940

IMPORTANT SAFETY INSTRUCTIONS
To get the most out of the many functions of this machine and operate it insafety,it is necessary
to use this machine correctly. Please read this Instruction Manual carefully before use. We hope you
will enjoy the use of your machine for a long time. Please remember to keep this manual in a safe
place.
1. Observe the basic safety measures, including, but not limited to the following ones, whenever you
use the machine.
2. Read all the instructions, including, but not limited to this Instruction Manual before you use the
machine, in addition, keep this InstructionManual so that you may read it at any-time when necessary.
3. Use the machine after it has been ascertained that it conforms with safety rules/standards valid in
your country.
4. All safety devices must be in position when the machine is ready for work or in operation The
operation without the specified safety devices is not allowed.
5. This machine shall be operated by appropriately-trained operators.
6. For your personal protection, we recommend that you wear safety glasses.
7. For the following, turn off the power switch of disconnect the power plug of the machine from the
receptacle.
7-1 For threading needle(s) and replacing bobbin.
7-2 For replacing part(s) of needle, presser foot, throat plate, feed dog, cloth guideetc.
7-3 For repair work.
7-4 For when leaving the working place of when the working place is unattended.
8. If you should allow oil, grease, etc. used with the machine and devices to come in contact with your
eyes or skin or swallow any of such liquid by mistake, immediately wash the contacted areas and
consult a medical doctor.
9. Tampering with the live parts and devices, regardless of whether the machine is powered, is
prohibited.
10. Repairing, reforming and adjustment works must onlybe done by appropriatelytrained technicians
or specially skilled personnel.
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 speciallyskilled personnel. Whenever your find a failure
of any of electrical components, immediately stop the machine.
13. Periodically clean the machine throughout the period of use.
14. Grounding the machine is always necessary for the normal operation of the machine. The machine
has to be operated in an enviorment that is free from strong noise sources such as high-frequency
welder.
15. An appropriate power plug has to be attached to the machine by electric technicians, Power plug
has to be connected to grounded receptacle.
16. Remodel or modify the machine in accordance with the safety rules/standards while taking all the
effective safety measures. We assumes no responsibility for damage caused by reforming or
modification of the machine.
17. The machine is only allowed to be used for the ppose intended. Other used are not allowed.
18. Warning hints are marked with the two shown symbols.
Danger of injury to operator or service staff
Items requieren special attention

FOR SAFE OPERATION
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.
1. To avoid personal injury, never operate the machine with any of the belt
cover, finger guard of 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 handwheel,
cover and the motor while the machine is in 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 keep 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, be careful not to allow your fingers in
the machine when tiling/raising the machine head.
7. To avoid possible accidents because of abrupt start of the machine, turn
OFF the power to the machine when tiling the machine head.
8. If your machine is equipped with a serve-motor, the motor does not
produce noise while the machine is at rest. To avoid possible accidents due
to abrupt start of the machine, be sure to turn OFF the power to the
machine.
9. To prevent possible accidents because of electric shock or damaged
electrical component(s), turn OFF the power switch in prior to the
connection/disconnection of the power plug.

Precautions Prior to Startup
1. The machine head is coated with a thick layer of rust-prevention grease before
encasement, and the encased machine head may possibly be subjected to grease hardening
and dust buildup on the machine surface in process of long storage and long-haul traffic;
therefore, take care to remove the grease and dust from the surface using soft cloth and
gasoline.
2. Though the machine was inspected and tested with care before factory leaving, it
might be affected by violent vibration resulting in looseness or distortion of the machine
parts; therefore the operator shall thoroughly check the machine, turn the upper wheel by
hand and check it for difficulty in free rotation, slight impact, and other uneven resisting force
or abnormal noises, and make appropriate adjustment if any to restore the machine state
before formal trial run.
3. Never start up the machine if the oil liquid level in the oil box falls outside the normal
range.
4. The upper wheel shall rotate counterclockwise (when it is viewed from the lateral
surface of the upper wheel) when the machine is operating.
5. Check whether the voltage and phases indicated on the electric-control data plate
are correct.
6. The date of manufacture is indicated on the certificate of conformity.
Precautions for Use
1. Never touch the needle by hand when the machine is powered on or while it is
operating.
2. Never put your finger into the protection cover of take-up lever during operation of
the machine.
3. The operator must not put his finger into the needle guard bracket when he feeds
the sewing materials by hand.
4. Operator must trim off the electricity supply before he turns over the machine head
or removes the hand cover.
5. The operator must trim off the electricity supply before he gets away from the
machine.
6. Prohibit the head, hands and anything to approach the upper wheel and
bobbinwinder while the machine is operating.
7. Never remove or mount the protection cover or other protection devices before the
machine is stopped.
8.Never wipe up the surface of machine head using paint thinner such as acetone.

TABLE OF CONTENTS
1. MACHINE SPECIFICATIONS .............................................................................1
2. INSTALLATION......................................................................................................1
2.1. Installation .............................................................................................................. 1
2.2. Machine head......................................................................................................... 2
2.3. Cotton stand ........................................................................................................... 2
3. LUBRICATION ........................................................................................................3
4. THREADING THE UPPER THREAD .................................................................4
5. ADJUSTING THE NEEDLE AND ROTARY HOOK TIMING.......................4
6. ADJUSTMENT OF THE PEDAL..........................................................................5
6.1. Standard adjustment ............................................................................................ 6
6.2. Adjustment of the amount of wire transfer ................................................... 6
6.3. Adjustment of the Height of feed dog............................................................ 7
6.4. Adjust the lean of feed dog ................................................................................ 8
7. ADJUSTING THE TENSION OF STITCH THREAD.......................................9
8. ADJUSTING THR AMOUNT OF OIL (OIL SPLASHES) IN THE HOOK
..............................................................................................................................................10
9. THREAD TRIMMING .........................................................................................12
10. PEDAL PRESSURE AND PEDAL STROKE.....................................................13

1. MACHINE SPECIFICATIONS
2. INSTALLATION
2.1. Installation
620
620M
620H
USE
Medium-weight materials
Heavy-weight materials
MAX. Sewing speed
5000sti/min
4000sti/min
MAX.Stitch length
5mm
7mm
7mm
Presser
foot
height
lifting lever
5.5mm
Knee lifter
13mm
automatic
9.5mm
Feed tooth height
1.0mm
1.2mm
Needle
DBx1 9#-18#
DPx5 18#-22#
Lubricant
NO.10 White oil
①. Speed controler
②. Connecting rod
①. Nail (8pcs)
②. Rubber cushions (2pcs)
③. Head cushions(small) (2pcs)
④. Head cushions(big) (2pcs)
⑤. Tray (1pcs)
1

2.2. Machine head
①. Machine head
②. Hinges (2pcs)
③. Frame support bar
2.3. Cotton stand
①Cotton stand
NOTE：
Securely tighten the nut ④,so that
the two rubber cushions ②and
the washer ③are securely
clamped and so that the cotton
stand ①does not move.
2

3. LUBRICATION
WARNING:
Turn OFF the power before starting the work so as to prevent accidents
caused by abrupt start of the sewing machine.
1) Fill oil pan ①with 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 after lubrication, you will see splashing oil through oil
sight window ②if the lubrication is adequate.
4) Note that the amount of the splashing oil is unrelated to the amount of the lubricating
oil.
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.
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 by
turning adjust pin .
2) The mInimum amount of oil is reached
when marker dot is brought close to needle
bar crank by turning the adjust pin in
direction .
3) The maximum amount of oil is reached
when marker dot is brought to the position
just opposite from the needle bar crank by turning the adjust pin in direction .
3

4. THREADING THE UPPER THREAD
CAUTION
Turn off the power switch before threading the upper thread.
The machine may operate it the treadle is depressed by mistake, which
could result in injury.
Turn the machine pulley and raise the thread
take-up ①before threading the upper
thread.
This will make threading easier and it will
prevent the thread from coming out at the
sewing start.
5. ADJUSTING THE NEEDLE AND ROTARY HOOK TIMING
The tip of the rotary hook ③should be aligned with the center of the needle ④when the
needle bar ①moves up 1.8mm (2.2mm for -M and -H specifications) from its lowest position
to the position where reference ling B is aligned with the lower edge of the needle bar bush
②as shown in the illustration. (the distance from the upper edge of the needle hole to the
rotary hook tip will be 0.5 to 0.7mm at this time).
1. Turn the machine pulley to raise the needle bar ①from its lowest position until
reference line B is aligned with the lower edge of the needle bar bush D ②as shown
in the illustration.
2. Loosen the set screws ⑤, and then align the tip of the rotary hook ③with the center
of the needle ④, The distance between the tip of the rotary hook ③and the needle
④should be approximately 0-0.05mm.
3. Securely tighten the set screws ⑤.
4

6. ADJUSTMENT OF THE PEDAL
CAUTION
Turn off the power before starting the work so as to prevent accidents
caused by abrupt start of the sewing machine.
1. Adjusting the angle of treadle
1) Adjust the angle of treadle only by adjusting
the length of treadle connecting rod: unscrew
screw ①, and adjust the length of treadle
connecting rod by moving upward/downward
the upper connecting rod ②and lower
connecting rod ③.
2) Screw down screw ①when adjustment is over.
2. Adjustment of the strength of pedalThe sewing
machine run at a low speed when step forth on the panel slightly. If the
strength is insufficient, hang the stepping adjustment spring ④on the
panel spiral arm driving lever ⑤in order to adjust strength.(a is the
minimum stepping strength ,b,c,d increase gradually)
3. Adjustment of stepping return strength
1) Loosing nut ⑥and turn bolt ⑦to adjust stepping return strength : tighten bolt ⑦,
the strength increases;loosen bolt ⑦, the strength decreases.
2) Tighten nut ⑥after adjusting stepping return strength.
Pedal operation
1. The treadle has 4 operation levels:
1) The machine runs at low sewing speed when
you lightly depress the front part of the pedal.
(as show in the picture B)
2) The machine runs at high sewing speed when
you further depress the front part of the
pedal.(as show in the picture A)
3) Penal back to the initial position when stop stepping on it and the machine stop
working.(needle in the upper or down position)(as show in the picture C)
4) The machine trims threads when you fully depress the back part of the pedal.(as show
in the picture A)
5) When the auto-lifer is used,one more operating switch is provided between the
sewing machine stop switch and thread trimming switch. The presser foot goes up
when you lightly depress the back part of the pedal(D), and if you further depres the
back part,the thread trimmer is actuated.
5

6.1. Standard adjustment
CAUTION
Maintenance and inspection of the sewing machine should only be carried
out by a qualified.
Ask your dealer or a qualified electrician to carry out any maintenance and
inspection of the electrical system.
If any safely devices have been removed, be absolutely sure to re-install
them to their origin positions and check that they operate correctly before
using the machine.
Use both hands hold the machine head when tilting it back or returning it
to its original position. If only one hand is used the weight of the machine
head may cause your hand to slip, and your hand may get caught.
Turn off the power switch and disconnect the power cord from the wall
outlet at the following times. Otherwise the machine may operate if the
treadle is depressed by mistake, which could result in injury.
•When carrying out inspection, adjustment and maintenance.
•When replacing consumable parts such as the rotary hook and knife.
6.2. Adjustment of the amount of wire transfer
1. Unscrewing the screw ①.
2. Move the right thread hook ②to adjust : the thread
amount of thread take-up lever will increase if turned
it towards left (A direction), while turning it to the right
(direction B) and the thread amount of thread take-up
lever will decrease accordingly.(The standard position
is obtained when graduation line C on right thread
hook is aligned to screw center.)
3. Remember to tight the screw ①after adjusting.
6

6.3. Adjustment of the Height of feed dog
1. Turn the pulley until the feed dog
rises to the highest position.
2. Turn over the sewing machine head
on the supporting bar.
3.Unscrewing the tightened screw ①
in thefeed lifting crank ②.
4. Rotating the feed lifting crank ②to
make adjustment: the feed dog will
be higher when the feed lifting crank ②is turn towards A direction; turn towards B direction
the feed dog will be lower. (When the feed dog in the highestposition, the standard height
of the type of medium-heavy machine is 0.8~1.0mm and standard height of the heavy duty
machine is 1.1~1.3mm）.
5. Remember to tighten the tightening screw ①in the feed lifting crank ②after adjusting.
7

6.4. Adjust the lean of feed dog
1. Turn the pulley until the feed dog ④rises
to the highest position.
2. Turn over the sewing machine head on the
supporting bar.
3. Unscrewing the tightening screw ①in the
teeth pedestal ②.
4. Adjust the eccentric pin ③by screw driver:
Fall front site of tooth feed when moving
the eccentric pin ③towards A, and raising it
when move towards B.(When raising the
tooth feedto the highest position, The
standard lean position of feed dog is that
mark C on eccentric pin ③should be at the
same level D with mark on the teeth
pedestal ②and the feed dog should be
parallel with needle plate.).
5. Remember to tighten the tightening
screw ①in the teeth pedestal ②after
adjusting.
•In order to prevent puckering,lower the front of the feed dog.
•In order to prevent the material from slipping,raise the front of the feeddog.
•The height of the feed dog will change after the angle has been adjusted,so it will be
necessary to readjust the height of the feed dog.
8

7. ADJUSTING THE TENSION OF STITCH THREAD
CAUTION
Turn off the power switch before removing or inserting the bobbin case.
The machine may operate of the treadle is depressed by mistake, which
could result in injury.
1. Adjusting the tension of bobbin thread Hold the end of a
thread which hanging from the bobbin case and use the
adjusting rotating scerw①to regulate. The tension of the bottom
thread is become strong by tight the screw ①, loose the screw
to make it weak.
The adjust standard of the bottom thread tension: Rotating the adjusting screw ①till the
bobbin case can falling slowly by it’s own weight.
2. Adjusting the tension of needle thread
After the lower thread tension has been adjusted,adjust the upper thread tension so
thata good,even stitch is obtained.
1) Lower the presser foot by using the lifting lever.
2) Adjust by turning the tension nut ②: The
tension of the upper thread will become strong
when turning toward the clockwise(A),
otherwise weak when toward anti-clockwise
(B).
Upper thread
Lower thread
Upper thread tension too weak or
Lower thread tension too strong
Upper thread tension too strong
or Lower thread tension too weak
9

8. ADJUSTING THR AMOUNT OF OIL (OIL SPLASHES) IN THE HOOK
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.
①②
* When carrying out the procedure described below in 2, remove the slide plate and
take extreme caution not to allow your fingers to come in contact with the hook.
1) If the machine has not been sufficiently warmed up for operation, make the machine
run idle for approximately three minutes. (Moderate intermittent operation)
2) Place the amount of oil (oil splashes) confirmation paper under the hook while the
sewing machine is in 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).
•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
will increase the amount of oil (oil sports)
in the hook, or in “-“ direction (in
direction ) will decrease it.
2) After the amount of oil in the hook has
been properly adjusted with the oil amount
adjustment screw, make the sewing machine run idle for approximately 30 seconds to
check the amount of opil in the hook.
Amount of oil (oil splashes)
confirmation paper
Position to confirm the amount of oil
(oil splashes)
10

8. ADJUSTING THE AMOUNT OF OIL (OIL SPLASHES) IN THE HOOK
•Sample showing the appropriate amount of oil
1) The amount of oil shown in the
samples of 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. (If 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 producto 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)
Appropriate amount of oil (small)
Appropriate amount of oil (large)
11

9. THREAD TRIMMING
1. When use thick thread or not trim,
loosen the screw①and ②, adjustment
the moving knife ③angle.
2. Knife ③tilted to the inside, the knife
surface presser drop.
3. Adjust the knife ③anger, then
retighten the screw ①and screw ②.
4. After adjustment, manually move up
and down the knife holder to confirm
whether the machine can trim thread
normally or not.
12

10. PEDAL PRESSURE AND PEDAL STROKE
Waring
Turn OFF the power before starting thr work so as to prevent accidents caused by
abrupt start of the sewing machine.
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 ③in to the right hole.
13