Singer QUANTUM 9920 User manual

SERVICE MANUAL
9940/20/10
9/20/2003

SERVICE MANUAL
2
Table of contents
REMOVING THE EXTERIOR PARTS ............................................................. 3
A. Light Cover ................................................................................................ 3
. ase .......................................................................................................... 3
C. Top Cover (Flap) ....................................................................................... 4
D. Hinge Cover .............................................................................................. 4
E. Thread Tension Cover .............................................................................. 4
F. Side Enclosure .......................................................................................... 5
G. Handle and Unit Cover .............................................................................. 5
H. Needle Plate .............................................................................................. 6
I. Front Enclosure ......................................................................................... 7
J. Rear Enclosure ......................................................................................... 8
K. Front panel (from Front Enclosure) ........................................................... 8
REPLACING THE EXTERIOR PARTS ............................................................ 9
K. Front panel (to Front Enclosure) ............................................................... 9
J. Rear Enclosure ......................................................................................... 9
I. Front Enclosure ....................................................................................... 10
H. Needle Plate ............................................................................................ 10
G. Handle and Unit Cover ............................................................................ 11
F. Side Enclosure ........................................................................................ 12
E. Thread Tension Cover ............................................................................ 12
D. Hinge Cover ............................................................................................ 12
C. Top Cover (Flap) ..................................................................................... 13
. ase ........................................................................................................ 13
A. Light Cover .............................................................................................. 14
CHECK AND ADJUSTMENT ......................................................................... 15
1. HEIGHT OF NEEDLE AR ..................................................................... 15
2. GAP ETWEEN NEEDLE AND HOOK .................................................. 16
3. TIMING OF THE HOOK .......................................................................... 17
4. HEIGHT OF THE FEED DOG ................................................................. 18
5. NEEDLE PLATE AND NEEDLE POSITION ........................................... 19
6. TIMING OF THE UPPER AND LOWER SHAFT..................................... 20
7. ADJUSTING THE FORWARD REVERSE STITCH ................................ 21
8. O IN WINDER ................................................................................... 22
9. HEIGHT AND DIRECTION OF PRESSER FOOT .................................. 23
10. HEIGHT OF NEEDLE THREADER......................................................... 24
11. ADJUSTMENTS FOR UTTONHOLE LEVER POSITION .................... 25
12. MOTOR ELT TENSION ........................................................................ 26
13. TIMING ELT TENSION ......................................................................... 26
14. ACKLASH OF HOOK GEAR ................................................................ 27
15. UPPER THREAD TENSION UNIT .......................................................... 28
16. ADJUSTING THE LOWER THREAD TENSION ..................................... 28
17. FLATNESS OF THE ASE ..................................................................... 28
LOCATING THE DEFFECTED ELECTRICAL PART .................................... 29
1. To turn off the audible beep .................................................................... 29
2. The self-diagnostic program .................................................................... 29
3. Messages on LCD (9940/9920) .............................................................. 33
4. Electrical Parts Connection ..................................................................... 34
SINGER® is a registered Trademark of The Singer Company Ltd.

SERVICE MANUAL
3
REMOVIN THE EXTERIOR PARTS
A. Light Cover
1. Loosen the light cover set screw (a).
. ase
1. Remove the extension table.
2. Tilt the machine backward and remove the 3 base set
screws (a, b, c). Remove the base.
2. Pull light cover as shown so that the light cover hook
(b) will come off.
The exterior parts should be removed in sequence as
followings.
CAUTION:
Always disconnect the main lead plug from electcrial
outlet when removing the exterior parts.
3. Carefully disconnect the connector with holding the
lever (d).
This connector connects terminal box and power
circuit board.
1
a
2
b
2a
bc
3d

SERVICE MANUAL
4
C. Top Cover (Flap)
1. Open the top cover.
2. Push the right side of top cover backward and remove
the hinge (a).
D. Hinge Cover
1. Insert the tip of screw driver and pull up the front side
of hige cover.
E. Thread Tension Cover
1. Remove the screw (a).
3. Slide the top cover to the right and remove the hinge
(b).
2. Push the Thread tension cover backward ; 2 hooks (b,
c) will come off.
3. Pull up the cover.
2
a
3
b
1
1
2
a
bc

SERVICE MANUAL
5
F. Side Enclosure
1. Remove the screw (a).
G. Handle and Unit Cover
1. Remove the unit cover set screws (a, b) and handle
set screws (c, d).
2. Stand up the handle.
2. Push the side enclosure slightly backward to come off
the 2 hooks (b, c).
3. Pull the side enclosure to the right and remove it.
1
a
2
b
c
3. Push the right side of unit cover backward so that the
hook of unit cover will come off and pull up.
1b
a
c d
3

SERVICE MANUAL
6
H. Needle Plate
1. Remove the presser foot.
2. Remove the 2 screws (a, b) holding the needle plate.
4. Next, push the left side of unit cover backward and
pull up it to come off from the thread guide cover. 4
5. Slide the handle and unit cover to the left and remove
them.
6. Carefully disconnect the connector which connects to
the contrast control board.
5 6
2
ab
3. Lift up the right side of needle plate and remove it. 3

SERVICE MANUAL
7
I. Front Enclosure
1. Loosen the screw (a).
2. Push the left side of rear enclosure (b) and pull the
front enclosure (hook-c will come off).
3. Pull up the front enclosure and come off the hook-d.
4. Pull the enclosure to the left and come off the hook-e.
5. Push the rear enclosure to the left and come off the
hook-f.
6. Disconnect the 2 connectors (g, h) from the machine
and remove the front enclosure.
1
2
a
b
c
3 4
d
e
5
f
6
gh

SERVICE MANUAL
8
J. Rear Enclosure
1. Lower the presser foot lifter.
2. Remove the 3 screws (a, b, c).
(screw-c is longer than others.)
3. Pull the rear enclosure backward and remove it.
K. Front panel (from Front Enclosure)
1. Disconnect the 2 connectors from the front panel (a:
Reverse switch board) (b: Controller jack assy.)
TYPE (Locked by hooks)
2. Push the lower 3 hooks (j, k, l) downward to come off
them.
3. Push the upper 3 hooks upward to come off them.
4. Pull up the front panel backward and remove it. (3
hooks on front panel will come off)
2
c
b
a
1
b
a
4
2
TYPE A (Secured by 4 screws)
2. Remove the 4 screws (c, d, e, f ).
3. Push the lower hook (g) downward and push the
upper hooks (h, i) upward to come off.
c
d
e
f
g
i
h
2
jl
k

SERVICE MANUAL
9
REPLACIN THE EXTERIOR PARTS
K. Front panel (to Front Enclosure)
1. Pass the cords through the openings of front enclo-
sure.
2. Ride the 3 hooks of front panel on the front enclosure.
J. Rear Enclosure
1. Lower the presser foot lifter.
2. Replace the rear enclosure.
3. Retighten the 3 screws (a, b, c).
(Screw-c is longer than others and replace loosely.)
The exterior parts should be replaced in reverse se-
quence when removing. (K. to A.)
TYPE (Locked by hooks)
3. Push front enclosure around the hook and fit them in
place.
4. Connect the 2 connectors (a: Reverse switch board)
(b: Controller jack assy.)
1 2
4
b
a
3
c
b
a
3
3
TYPE A (Secured by 4 screws)
3. Push front enclosure around the hook and fit them in
place.
Retighten the 4 screws.

SERVICE MANUAL
10
I. Front Enclosure
1. Connect the 2 connectors (g, h) to the machine.
H. Needle Plate
1. Insert the hook (c) of needle plate to the machine.
2. Replace the front enclosure so that the 4 hooks will fit
in place.
3. Push lower end of front enclosure arm backward and
retighten the screw (a).
2. Retighten the screws (a, b).
1
gh
2
3
a
2
ab
1c

SERVICE MANUAL
11
G. Handle and Unit Cover
1. Set the handle to the unit cover and insert the handle
hinge pin into the left side hole of handle from left
side.
2. Place the handle and unit cover onto the top of
machine.
3. Connect the connector to the contrast control board.
4. Insert the hinge pin on the machine into the right side
hole of handle.
5. Replace the unit cover so that the each hook fit into
place.
6. Retighten the handle set screws (c, d) and unit cover
set screws (a, b).
1
2
3
4
5b
a
c d
6

SERVICE MANUAL
12
F. Side Enclosure
1. Replace the side enclosure so that the each hook fit
into place.
2. Retighten the screw (a).
E. Thread Tension Cover
1. Replace the thread tension cover so that the each
hook fit into place.
2. Retighten the screw (e).
D. Hinge Cover
1. Insert the rear hook into the machine and push the
hinge cover.
1 2
a
1a 2
1

SERVICE MANUAL
13
. ase
1. Tilt the machine backward.
2. Connect the connector so that the hook (d) will fit into
place.
3. Replace the base and retighten the 3 screws.
C. Top Cover (Flap)
1. Slide the top cover to the left so that the hook (b) will
fit onto the pin of unit cover.
2. Pull the right side of top cover and snap on the hook
(a) onto the pin of unit cover.
1
2
b
a
3
2d

SERVICE MANUAL
14
A. Light Cover
1. Loosen the light cover set screw (a).
2. Replace the ligth cover so so that the hook (b) will fit
into place.
3. Retighten the screw (a).
1
a
b
2
3
3

SERVICE MANUAL
15
CHECK AND ADJUSTMENT
1. HEI HT OF NEEDLE BAR
Height of needle bar could be the cause for stitches to
skip. Check as the following procedures.
1. Set the pattern to [Utility stitch No.1] which is straight
stitch on center needle position.
2. Raise the needle bar to its highest point by turning the
handwheel toward you. Remove the presser foot.
Remove the needle plate. Lift up the bobbin holder
and remove it.
3. Turn the handwheel toward you until the needle
comes to its lowest point.
4. Then, the spacing between the surface of hook race
and the top edge of needle eye must be (4.9±0.1
mm).
If this spacing is not correct, adjust as follows.
5. Remove the light cover.
6. Remove the 2 screws (a, b) and remove the take up
lever cover and bracket (c) by sliding it upward.
( ottom hook of cover will come off)
1
4.9±0.1 mm
2
3
4
6
a
b
c
7d
7. Raise the needle bar 4.9mm from its lowest point by
turning the handwheel.
Loosen the screw (d) on the needle bar holder. (2 mm
hex. wrench)
Adjust the needle bar so that the top edge of needle
eye is aligned with the surface of hook race.
Retighten the screw (d) and check the height again.
CAUTION: Do not change the needle bar direction at
this adjustment. The long groove of needle must be
facing frontwards.
8. Replace the take up lever cover and screws.

SERVICE MANUAL
16
2. AP BETWEEN NEEDLE AND HOOK
If the needle hits against the hook, it may be the cause
of needle and thread breakages. If the gap between
needle and hook is too big, it will cause to skip stitches.
Check and adjust as follows:
Prior to make this adjustment, check that the needle is
not bent and the needle is inserted correctly.
1. Remove the needle plate and bobbin holder.
2. Set the pattern at [Utility No. 2]. (Straight stitch on left
needle position.)
3. Turn the handwheel toward you until the needle will
cross over the hook.
4. Then, check the gap between needle and hook is
about 0.10 to 0.20 mm.
If the needle is hitting against the hook or if the gap is
too much, adjust as follows:
5. Remove the light cover.
2
1
3
0.10-0.20 mm
View from
upward
4
6
6. Adjust the gap by turning the adjusting screw (a) with
2 mm hex. wrench.
• If the gap is too big, turn the screw to the left with
viewing from frontward.
• If the needle is hitting the hook, turn the screw to the
right with viewing from frontward.
7. Replace the bobbin holder and needle plate and light
cover.
a

SERVICE MANUAL
17
3. TIMIN OF THE HOOK
Prior to making this adjustment, be sure that the needle
bar is set at the correct height. (Sec. 1)
Check the timing of hook as follows:
1. Remove the needle plate and bobbin holder.
2. Set the pattern at [Utility No. 2]. (Straight stitch on left
needle position.)
3. Turn the handwheel toward you until the needle is at
its lowest point.
4. Then, turn the handwheel slowly to turn the hook
counter-clockwise until the tip of hook is aligned with
the right side of needle.
At this time, the gap between the tip of hook and the
top edge of needle eye should be (1.3±0.2 mm).
If the gap is too small or too large, adjust as follows:
5. Remove the front enclosure.
1
4
6
2
1.3±0.2 mm
a
6. Loosen the two 2 screws (a) on the lower shaft gear
with a 2.5 mm hex. wrench.
7. Turn the hook race by hand so that the tip of hook will
align with the right side of needle.
8. In this position, hold the hook race with your left hand
and turn the handwheel toward you to obtain the
correct gap (1.3 mm).
9. Tighten the screws and check the timing again.
10.Replace the front enclosure.

SERVICE MANUAL
18
4. HEI HT OF THE FEED DO
If the feed dog does not come up over the needle plate
enough, it will result in insufficient and/or uneven feed of
fabrics.
1. The feed dog should come up over the needle plate
(1.0-1.1 mm) when its highest position.
If it does not come up enough, adjust as follows:
2. Remove the needle plate.
1
3
1.0-1.1 mm
a
b
c
d
e
3. Lower the presser foot lifter. Turn the handwheel until
the feed dog comes to its highest position.
• If the feed dog is too low;
Turn the adjusting screw (a) (1.5mm hex. wrench)
clockwise until correct height is obtained.
Turn the screw (b) clockwise until the cam follower (c)
touches the feed rocking cam (Right)(d).
(To check it, remove the front enclosure and see
frontward.)
• If the feed dog is too high;
Turn the screws (a) and (b) counterclockwise in a few
turns.
Push the left side of feed base strongly (e) (feed dog
will come down)
Check that the feed dog came lower than the correct
height. If it is not so, turn the screws counterclockwise
again and lower the feed base.
After the feed dog is lower than the correct height,
adjust the feed dog height same as “If the feed dog is
too low”.
4. Check that the cam followers (c) , (e) have to be even
height and they have no opening to each cam (d), (f).
5. Re-check the height and motion of feed dog by turning
the handwheel.
4
c
d
e
f

SERVICE MANUAL
19
5. NEEDLE PLATE AND NEEDLE POSITION
1. When the straight stitches is set at center needle
position (Utility No.1), the needle should fall into the
center of needle plate hole (the distance needle and
edge of hole at each side).
If it is not so, adjust as follows:
2. Set the pattern at [Utility No.1].
3. Remove the presser foot and the light cover.
1
2
4
a
b
5 6
4. Loosen the center screw (a).
5. Turn the adjusting screw (b) left or right until the
needle falls center position into the hole.
• When you turn the screw to the right, needle wiil move
to the left.
• When you turn the screw to the left, needle wiil move
to the right.
6. Retighten the screw (a) and re-check the position of
needle.
7. When you have adjusted the this position, check the
timing of the hook again. (Sec. 3)

SERVICE MANUAL
20
6. TIMIN OF THE UPPER AND LOWER SHAFT
The upper and lower shaft must be positioned correctly
as follows.
1. Remove the front enclosure.
2. Turn the handwheel toward you until the needle is its
lowest point. At this time, the mark (a - very small
molded line on edge) on the lower shaft timing pulley
must be facing toward you.
If it is not so, adjust as follows:
2
a
3
b
4 5
7 8
3. Loosen the screw (b) tightening the tension pulley
bracket.
4. Slip out the timing belt from lower shaft timing pulley.
5. Turn the lower shaft timing pulley so that the mark
faces toward you.
6. Hook the timing belt on the pulley.
7. Push the tension pulley bracket so that the edge of
bracket should be 0-1 mm higher than the casting.
8. Retighten the screw (b)
9. Check the timing again and replace the front enclo-
sure.
10. When you have adjusted it, check the timing of the
hook again. (Sec. 3)
0-1 mm