ELNA Elinita EF72 User manual

SERVICE MANUAL
MODEL: ef72
First Edition: 09 April 2020

INDEX
Changing external parts
Face plate......................................................................................................................................................... 1
Top cover .......................................................................................................................................................... 1
Belt cover ......................................................................................................................................................... 2
Base ................................................................................................................................................................. 2
Power supply cover .......................................................................................................................................... 3
Thread cutter cover .......................................................................................................................................... 3
Front cover ....................................................................................................................................................... 4
Thread guide coverr ......................................................................................................................................... 5
Arm thread guide unit ....................................................................................................................................... 6
Replacing Electronic Components
Changing the printed circuit board A................................................................................................................ 7
Changing the printed circuit board K................................................................................................................ 8
Changing the printed circuit board F and slide volume.................................................................................... 9
Changing LCD................................................................................................................................................ 10
Wiring diagram ................................................................................................................................................11
Mechanical Adjustment
Needle drop position ...................................................................................................................................... 12
Backlash between hook drive gear and lower shaft gear .............................................................................. 13
Hook timing .....................................................................................................................................................14
Adjustment of needle bar height..................................................................................................................... 15
Clearance between needle and tip of the rotary hook (1) .............................................................................. 16
Clearance between needle and tip of the rotary hook (2) ...............................................................................17
Adjustment of height and direction of presser bar.......................................................................................... 18
To adjust the feed dog height ......................................................................................................................... 19
To replace needle thread tension unit ............................................................................................................ 20
To adjust the upper thread tension release (1)............................................................................................... 21
To adjust the upper thread tension release (2)............................................................................................... 22
Adjusting the needle thread tension............................................................................................................... 23
To adjust the bobbin winder stopper .............................................................................................................. 24
Needle threader hook position ....................................................................................................................... 25
To adjust thread cutter switch......................................................................................................................... 26
To adjust thread drawing lever ....................................................................................................................... 27
Replacing the thread take-up lever ............................................................................................................... 28
To attach lower shaft. ..................................................................................................................................... 29
Synchro belt ................................................................................................................................................... 30
To replace driving motor and adjust belt tension............................................................................................ 31
Upper shaft shield plate position.................................................................................................................... 32
Adjusting buttonhole lever position ................................................................................................................ 33
Stretch stitch feed balance............................................................................................................................. 34
Adjustment of presser bar lifter switch position.............................................................................................. 35
To adjust and replace needle plate sensor switch ......................................................................................... 36
To replace switching power supply................................................................................................................. 37
To replace and adjust drop feed micro switch................................................................................................ 38
Feed dog troubleshooting .............................................................................................................................. 39
Self diagnosis ............................................................................................................................................40-44

1
Changing external parts (1)
To remove:
1. Remove the setscrew A to remove the face plate.
To attach:
2. Attach the face plate with the setscrew A.
Face plate
Top cover
To remove:
1. Remove the setscrews B (2 pcs.).
2. Remove the bobbin winder connector and remove the
top cover.
To attach:
3. Insertthebobbinwinderconnectorandxthetop
cover with setscrews B (2 pcs.).
* Turn the foot pressure dial lightly to attach the top
cover, if necessary.
Setscrew A
Face plate
Top Cover
Setscrew B Setscrew B
Bobbin winder connector

2
Base
To remove:
1. Remove the setscrews C (5 pcs.) and setscrew D to
remove the base.
To attach:
2. Attach the base with the setscrews C (5 pcs.) and the
setscrew D.
Setscrew C
Base
Changing external parts (2)
Belt cover
To remove:
1. Remove the top cover (refer to page 1).
Remove the caps (2 pcs.) and setscrews A (2 pcs.).
2. Loosen the setscrew B and remove the belt cover.
To attach:
3. Attach the belt cover and tighten the setscrew B.
4. Tighten the setscrews A (2 pcs.) and attach the
caps (2 pcs.).
Setscrew A
Belt cover
Setscrew A
Hook
Hook
Setscrew D
Block of
approximately
height 2 cm
Cap
Setscrew B
Base
Rubber foot
Rubber foot
Cap

3
Changing external parts (3)
Thread cutter cover
To remove:
1. Loosen the setscrew B and remove the thread cutter
cover.
To attach:
2. Attach the thread cutter cover with the setscrew B.
Setscrew B
Thread cutter cover
Power supply cover
To remove:
1. Remove the setscrews A (3 pcs.) and remove the
power supply cover.
To attach:
1. Attach the power supply cover with setscrews A
(3 pcs.).
Setscrew A
Setscrew A
Power supply cover
Hook

4
To remove:
1. Remove the face plate, top cover and belt cover (refer
to pages 1 and 2).
2. Loosen the setscrews A, B, C, D and E (6 pcs.).
3. Disconnect the LCD connector and printed circuit
board K connector from the printed circuit board A.
Remove the front cover.
To attach:
1. Follow the steps of removal procedure in reverse.
Setscrew B
Setscrew D
Changing external parts (4)
Front cover
Setscrew C
Front cover
Printed circuit board A
Setscrew E
Setscrew A
Printed circuit
board K
connector
LCD
connector

5
Changing external parts (5)
To remove:
1. Remove the face plate and the top cover (refer to
page 1).
2. Loosen the setscrews A and B, and remove the thread
guide cover.
To attach:
1. Follow the steps of removal procedure in reverse.
* Remove the thread guide cover carefully, not
to break the slit of the thread guide cover in the
section C.
Setscrew A
Setscrew B
Thread guide cover
Thread guide
cover
Slit
Section C
Thread guide cover

6
Changing external parts (6)
To remove:
1. Remove the face plate, top cover and thread guide
cover (refer to pages 1 and 5).
2. Remove the setscrew A.
Loosen the setscrew B, and remove the arm thread
guide (unit).
To attach:
1. Follow the steps of removal procedure in reverse.
Setscrew A
Setscrew B Arm thread guide (unit)
Arm thread guide unit

7
Changing the printed circuit board A
To remove:
1. Remove the front cover (refer to page 4).
2. Remove the setscrews A (4 pcs.) and disconnect
all the connectors from the printed circuit board A.
Remove the printed circuit board A.
To attach:
1. Follow the steps of removal procedure in reverse.
* Refer to page 11 for how to connect/ disconnect
the connectors to the printed circuit board A.
Printed circuit board A Setscrew A
Setscrew A
Setscrew A Setscrew A

8
Changing the printed circuit board K
To remove:
1. Remove the front cover (refer to page 4).
2. Disconnect the connector for printed circuit board F.
3. Remove the setscrews A (6 pcs.) and printed circuit
board K.
4. Disconnect the relay cable.
To attach:
1. Follow the steps of removal procedure in reverse.
Relay cable
Printed circuit board K
Setscrew A
Setscrew A
Connector for printed
circuit board F

9
Changing the printed circuit board F and slide volume
Printed circuit board F
To remove:
1. Remove the front cover (refer to page 4).
2. Disconnect the connector for printed circuit board F
and slide volume connector.
3. Remove the setscrews A (3 pcs.) and reomve the
printed circuit board F.
To attach:
1. Follow the steps of removal procedure in reverse.
Printed circuit board F
Snap ring
CS-3
Slide volume
To remove:
1. Remove the front cover (refer to page 4).
2. Disconnect the slide volume connector from the
printed circuit board F.
3. Remove the snap rings CS-3 (2 pcs.) and remove the
slide volume.
To attach:
1. Follow the steps of removal procedure in reverse.
* Insert the projection of slide volume into the
convexofspeedcontrolsliderandxitwiththe
snap rings (indicated by the arrow).
Slide volume
Printed circuit board F
Setscrew A
Snap ring CS-3
Connector for printed
circuit board F
Slide volume
connector
Slide volume
connector

10
Changing LCD
Setscrew A
LCD
Setscrew A
To remove:
1. Remove the front cover (refer to page 4).
2. Remove the setscrews A (4 pcs.) and remove the
LCD.
To attach:
1. Follow the steps of removal procedure in reverse.

11
Wiring diagram
Refer to this wiring diagram for locating the connectors on the printed circuit board A.
Jack cord (red 3P)
(Programming)
Zigzag motor (white 7P)
Feed motor (black 7P)
LED (face plate) (white 2P)
Drop feed micro switch
(black 2P)
DC motor (white 5P)
Bobbin winder motor (black 4P)
Buttonhole sensor
(black 3P)
Printed circuit board K
(white 28P)
Presser foot lifter switch
(white 4P)
Thread tension release
motor (black 7P)
Switching power supply
(white 4P)
Foot control (white 2P)
(Switching power supply)
Printed circuit board A
Thread cutter motor/switch
(white 6P)
Upper shaft sensor
(black 4P)
LCD (white 16P)
LED (arm) (red 2P)
LED (arm) (blue 2P)
Needle plate sensor
(white 3P)
ErP connector (green 2P)

12
Needle drop position
1. Remove the face plate. Select straight stitch #1 ( )
in mode 1 and check the needle drop position. Select
zigzag stitch #5 ( )in mode 1 and check the needle
drop position.
2. To adjust the needle drop position, loosen the
setscrew and turn the eccentric pin.
(The direction of eccentricity should be in the upper
part.)
* Remove the arm thread guide (unit) (refer to page
6).
3. Tighten the setscrew.
4. Attach the face plate.
When the straight stitch is selected, the needle should be positioned in the center of the
needle plate hole.
Whenthezigzagstitchisselectedwiththemaximumstitchwidthof9.0,theclearance
between the side of the needle and needle hole should be 0.2 mm or more.
Needle hole
0.2 mm or more
0.2 mm or more
A = B
Setscrew
Eccentricity is to be
adjusted in the upper
part.
Eccentricity
Eccentric pin

13
Backlash between hook drive gear and lower shaft gear
The gears turn smoothly and rotary play of the hook should be 0.8 mm or less when the tip
of hook is within the width of the feed dog as shown below.
1. Remove the base.
2. Remove the needle, needle plate and bobbin holder.
3. Turn the handwheel toward you so that the tip of the
rotary hook is within the width of feed dog. Turn the
rotary hook and check the clearance.
4. If the backlash is too much or too little, loosen
the setscrews of lower shaft bushings (front/rear)
and adjust the backlash following the adjustment
procedure in step 5.
* Turn the lower shaft bushings (front and rear) in
the same direction simultaneously and evenly.
5. If the backlash is too much, turn the lower shaft
bushing in direction A.
If the backlash is too little, turn the lower shaft bushing
in direction B.
6. Tighten the setscrews.
* After adjusting the backlash, check the needle bar
height and hook timing. Adjust if necessary.
7. Attach the bobbin holder, needle plate, presser foot
and needle.
8. Attach the base.
Lower shaft bushing (front)
Setscrew
Backlash: 0.8 mm or less with
hook tip within feed dog width
Tip of the rotary hook
(A)
(B)
Setscrew
Lower shaft bushing of the front side
Lower shaft bushing on the rear side
Setscrew
Lower shaft bushing (rear)

14
1. Attach the #14 needle.
2. Turn the power switch on and select the straight stitch
#1 ( ). Set the zigzag width at “0.0” (left needle
position) and turn the power switch off.
3. Remove the presser foot, needle plate and bobbin
holder.
4. Lower the needle bar to the lowest position by turning
the hand wheel toward you.
5. Remove the base (refer to page 2).
6. Loosen the setscrews (2 pcs.) of the lower shaft gear.
7. Move the needle bar 3.85 mm from the lowest
position by turning the hand wheel toward you.
8. Turn the lower shaft gear until the tip of the hook
meets the right side of the needle. Tighten the
setscrews (2 pcs.).
* After adjusting the hook timing, check the needle
bar height.
9. Attach the bobbin holder, needle plate and presser
foot.
10. Attach the base (refer to page 2).
Hook timing
The amount of ascending travel of the needle bar from its lowest position to the position
wherethetipoftherotaryhookexactlymeetstherightsideoftheneedleintheleftneedle
position (“0.0”) should be 3.70 to 4.00 mm.
Setscrew
Setscrew
Lower shaft gear
3.70 to 4.00 mm
Lowest needle
position
Needle #14
The tip of the rotary hook
exactlymeetstherightsideof
the needle.
Bobbin holder
Rotary hook

15
Adjustment of needle bar height
1. Attach the #14 needle.
2. Turn the power switch on. Select the straight stitch #1
( ). Set the zigzag width at “0.0” (left needle position).
* Do not turn the power switch off.
3. Remove the presser foot, needle plate and bobbin
holder.
4. Remove the face plate and arm thread guide (unit).
5. Turn the handwheel toward you until the tip of the hook
meets right side of the needle.
6. Loosen the setscrew with an allen wrench. Move the
needle bar and adjust needle bar height to 1.8 mm.
7. Tighten the setscrew with the needle setting groove to
the front.
8. Attach the arm thread guide (unit) and face plate.
9. Attach the bobbin holder, needle plate and presser
foot.
Needle setting groove
The hook meets right
side of the needle
Hook race
1.6 to 2.0 mm
Upper edge of
needle hole
Before proceeding with this adjustment, check the hook timing.
The distance between the upper edge of the needle eye and the tip of the hook should be in
the range of 1.6 to 2.0mm when the tip of the hook meets right side of the needle in the left
needle position (“0.0”) as the needle ascends from its lowest position.
Setscrew
Bobbin holder
Rotary hook
Needle #14

16
Clearance between needle and tip of the rotary hook (1)
The clearance between the needle and the tip of the rotary hook should be between -0.10 to
+0.05 mm.
Test pin
Tip of hook
-0.10 to +0.05mm
Clearance adjustment 1
1. Remove the top cover and face plate (refer to page 1 ).
2. Remove the presser foot, needle plate and bobbin
holder.
3. Attach the test pin.
4. Turn the power switch on and select the zigzag stitch
#5()andsetthestitchwidthtothemaximum“9.0”.
5. Loosen the setscrew and adjust the clearance
between the needle and the tip of the rotary hook as
-0.10 to +0.05 mm, by moving the needle bar
supporter in the directions of arrows.
6. Tighten the setscrew.
7. Attach the needle plate and check if the clearance
from the center to front or rear is 0.15 mm or less.
* If the clearance is more than 0.15 mm, adjust the
clearance in the procedure of clearance
adjustment 2 (refer to page 17).
Setscrew
Needle bar supporter
Needle hole
Clearance from the
center to front or
rear should be 0.15
mm or less.

17
Clearance adjustment 2
1. Remove the base. (Refer to page 2)
2. Loosen the setscrews A, B and C, and tighten
setscrew C lightly.
3. Adjust the clearance by moving the hook setting plate.
Turn the handwheel and make sure that the clearance
between the needle and the tip of the rotary hook is
-0.10 to +0.05 mm.
4. TightenthesetscrewsA,BandCrmly.
* Check the backlash between hook drive gear and
lower shaft gear, hook timing and needle bar hight.
Adjust, if necessary after the adjustment.
5. Attach the base, bobbin holder, needle plate, presser
foot and needle.
Setscrew C
Setscrew B
Setscrew A
Hook setting plate
Clearance between needle and tip of the rotary hook (2)
The clearance between the needle and the tip of the rotary hook should be between -0.10 to
+0.05 mm.

18
Adjustment of height and direction of presser bar
The clearance between the presser foot and the surface of the needle plate should be 6.0
mm when the presser foot is raised.
The presser foot should be parallel to the slot of the feed dog teeth when attached.
1. Raise the presser foot lifter.
2. Attach the zigzag foot A.
3. Set the foot pressure at “3”.
4. Drop the feed dog.
5. Remove the face plate (refer to page 1).
6. Loosen the setscrew on the presser bar supporter to
adjust the presser foot direction so that the slot for the
feed dog teeth and the zigzag foot should be parallel.
7. Place a 6 mm block between the presser foot and
the needle plate. Tighten the setscrew holding the
presser foot against the block.
8. Attach the face plate.
Setscrew
(2 mm width
acrossats)
Presser
foot
Presser bar
supporter
Needle plate
Approximately
6.0 mm
Block
Slot
Should be
parallel