Baby Lock PRO BL8800 User manual

MODEL BL8800
SERVICE MANUAL

- 1 -
TABLE OF CONTENTS
A.REMOVING THE FRONT COVER............................. 2
B. REPLACING THE FRONT COVER........................... 4
1. HEIGHT OF NEEDLE BAR........................................ 5
2. GAP BETWEEN NEEDLE AND HOOK ..................... 6
3. TIMING OF THE HOOK............................................. 7
4. HEIGHT OF THE FEED DOG.................................... 8
5. NEEDLE PLATE AND NEEDLE POSITON ............... 8
6. TIMING OF THE FEED MOTION .............................. 9
7. ADJUSTING THE FORWARD AND REVERSE
STITCH ................................................................. 10
8. BOBBIN WINDER .................................................... 10
9. HEIGHT AND DIRECTION OF PRESSER FOOT ... 11
10. HEIGHT OF NEEDLE THREADER ....................... 11
11. ZIGZAG TIMING • NEEDLE STOP POSITION ..... 12
12. MOTOR BELT TENSION....................................... 12
13. TIMING BELT TENSION........................................ 12
14. BACKLASH OF HOOK GEAR ............................... 13
15. UPPER THREAD TENSION UNIT......................... 13
16. ADJUSTING THE LOWER THREAD TENSION.... 13
LOCATING THE DEFFECTED ELECTRICAL PART .. 14
The self-diagnostic program......................................... 14
HOW TO CHECK......................................................... 14
a. Frequency of power line........................................... 14
b. Condition of switches and sensors .......................... 15
b-1. Adjustment for buttonhole lever position............... 16
c. Phase of feed pulse motor ....................................... 17
d. Phase of zigzag pulse motor.................................... 17
e. Condition of foot controller and speed control lever. 17
WARNING MESSAGES ON LCD ................................ 17
TROUBLE SHOOTING OF ELECTRICAL PARTS...... 18

a
b
c
fig. A-1
fig. A-2
fig. A-3
fig. A-4
d
fig. A-5
e
- 2 -
A.REMOVINGTHE FRONT COVER
1. Remove the set screw (a) and the light cover. (fig. A-1)
2. Remove the left side screw (b) inside the thread take
up lever cover. (fig. A-2)
3. Remove the screw (c) located on the backside of
machine, above the spool pin. (fig. A-3)
4. Tilt the machine backward.
Remove the 4 screws (d) and base. (fig. A-4)
5. Remove the 2 screws (e) on the bottom of front cover.
(fig. A-5)

f
fig A-6
fig A-7
g
fig A-8
h
ij
fig A-9
- 3 -
6. Stand up the machine.
The terminal cover will come out.
Insert the screwdriver into the hole of machine from
backside.
Hook the tip of driver into the groove of forward-
reverse adjusting knob (f). (fig A-6)
Slide them to the left and remove the knob.
7. Hook the tip of screwdriver to the front cover holder (g)
and pull down. (fig. A-7)
8. Tilt the machine backward again.
Hold the machine casting and push the left bottom
corner (h) of front cover upward. The hook inside of the
cover will come off. (fig. A-8)
9. Bring up the front cover carefully.
Disconnect the two cord connectors (i, j) from the CPU
curcuit board. (fig. A-9)
Terminal
cover

fig. B-1
fig. B-2
fig. B-3
fig. B-4
k
l
n
m
m
n
fig. B-5
f
- 4 -
B. REPLACINGTHE FRONT
COVER
1. Lower the presser foot lifter (k).
Turn the hand wheel toward you until the thread take-
up lever (l) rises to its highest point. (fig. B-1)
2. Connect the two cord connectors (i, j) from front cover
to the CPU circuit board on machine. (fig. A-9)
3. Set the front cover onto the machine casting so that
the tip of thread tension relasing lever (m) should be
hooked into the notch of tension guide (n). (fig. B-
2,3,4)
Check that the tension releasing mechanism has been
connected certainly.
4. Press the left side of front cover downward so that the
hook inside of cover will snap into a place.
5 Tighten the 2 screws (e) onto the bottom of front cover.
(fig. A-5)
6. Push up the front cover holder (g). (fig. A-7)
7. Insert the forward-reverse adjusting knob (f) into the
hole with the hook facing forward. (fig. B-5)
8. Replace the terminal cover and base, and tighten 4
screws (d) onto the base. (fig. A-4)
9. Tighten the screw (c) onto the back of machine. (fig. A-
3)
10.Tighten the screw (b) onto the take-up lever cover. (fig.
A-2)
11. Replace the light cover and screw (a). (fig. A-1)

fig. 1-1
fig. 1-2
fig. 1-3
a
5.2±0.2 mm
b
- 5 -
1. HEIGHT OF NEEDLE BAR
Height of needle bar could be the cause for stitches to
skip. Check as the following procedures.
1. Set the pattern number at “2” 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 set screw (a) and needle plate. Lift up the
bobbin holder and remove it. (fig. 1-1)
3. Turn the handwheel toward you until the needle comes
to its lowest point.
Then, the spacing between the surface of hook race
and the top edge of needle eye must be 5.2±0.2 mm.
(fig. 1-2)
(= Turn the handwheel until the top edge of needle eye
is aligned with the surface of hook race, at this time the
needle bar should be rising 5.2±0.2 mm from its lowest
point.)
If this spacing is not correct, adjust as follows.
4. Remove the light cover.
5. Lower the needle to its lowest point by turning the
handwheel.
6. Loosen (not remove) the screw (b) on the needle bar
holder. (fig. 1-3)
Raise the needle bar until the needle eye is aligned
with the hook race. Then, lower the needle bar 5.2 mm
and re-tighten the screw (b).
CAUTION: DO NOT change the needle bar direction at
this adjustment. The long groove of needle must be
facing frontwards.

fig. 2-1
fig. 2-2
0.02-0.1 mm
fig. 2-3
fig. 2-4
a
- 6 -
2. GAP BETWEEN NEEDLE AND
HOOK
If the needle hits aginst 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. (See Sec.
1-2)
2. Set the pattern number at “1” . (Straight stitch on left
needle position)
3. Turn the handwheel toward you until the needle will
cross over the hook. (fig 2-1)
Then, check the gap between needle and hook is
about 0.02 to 0.1 mm. (fig. 2-2)
If the needle is hitting against the hook or if the gap is too
much, adjust as follows:
4. Remove the light cover.
5. Remove the cap on the back side of machine. (fig. 2-3)
6. Loosen (do not remove) the lock screw with a hexagon
socket screw key (3 mm). (fig.2-4)
Adjust the gap by turning the adjusting nut (a) with an
open ended spanner (10 mm).
- If the gap is too big, turn the nut upward.
- If the needle is hitting the hook, turn the nut
downward.
When correct gap is obtained, hold the nut and
retighten the lock screw. Check the gap again.
7. Replace the cap and light cover. Replace the bobbin
holder and needle plate.

fig. 3-1
fig. 3-2
a
fig. 3-3
b
fig. 3-4
1.5-2.0 mm
- 7 -
3.TIMING OFTHE HOOK
Prior to making this adjustmetnt, be sure that the needle
bar is set at the correct height. (See sec. 1)
Check the timing of hook as follows:
1. Remove the needle plate and bobbin holder. (See sec.
1-2)
2. Set the pattern number at “1”. (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. (fig. 3-1)
At this time, the gap between the tip of hook and the
top edge of needle eye should be 1.5 to 2.0 mm.
If the gap is too small or too large, adjust as follows:
5. Tilt the machine backward.
Remove the bed lid by removing the screw (a) and
sliding bed lid to the left. (fig. 3-2)
6. Loosen the two screws (b) on the lower shaft gear with
a hexagon socket screw key (2.5 mm). (fig. 3-3)
7. Turn the hook race by hand so that the tip of hook will
align with the right side of needle.
In this position, hold the race with your left hand and
turn the handwheel toward you to obtain the correct
gap (1.5 to 2.0 mm). (fig. 3-4)
8. Tighten the screws (b) and check the timing again.
9. Replace the bed lid, bobbin holder and needle plate.

fig. 4-1
fig. 4-2
0.8+0.05 mm
-0
ab
fig. 5-1
fig. 5-2
a
- 8 -
4. HEIGHT OFTHE FEED DOG
If the feed dog does not come up over the needle plate
enough, it will result in insufficient and/or uneven feed of
fabrics.
The feed dog should come up over the needle plate
0.8+0.05 -0 mm. (fig. 4-1)
If it does not come up enough, adjust as follows:
1. Tilt the machine backward and remove the bed lid by
removing the screw and sliding it to the left. (See sec.
3-5)
2. Lower the presser foot lifter. Turn the handwheel until
the feed dog comes to its highest position.
3. Loosen the lock nut (a). Adjust the height of the feed
dog correctly by turning the inner screw (b). (fig. 4-2)
4. Hold the screw (b) and re-tighten the lock nut (a).
5. Re-check the height and motion of feed dog by turning
the handwheel.
5. NEEDLE PLATE AND NEEDLE
POSITON
When the zigzag width is set at maximum, the needle
should fall evenly into the both sides of needle plate hole (
the distance needle and edge of hole at each side). (fig.
5-1) If it is not so, adjust as follows:
1. Set the pattern number at “4” and stitch width to 5.
2. Remove the presser foot and the light cover.
3. Loosen the screw (a) located on the top of the needle
bar guide assembly. (fig. 5-2)
By slightly moving the needle bar left or right, adjust
the needle position so that the needle falls evenly into
the hole.
4. Tighten the screw (a) and re-check the position of
needle.

fig. 6-1
a
fig. 6-2
fig. 6-3
b
- 9 -
6.TIMING OFTHE FEED MOTION
If the feed motion is too fast of foo slow, it will be the
cause of fabfic puckers or needle breakage. Check and
adjust the feed timing as follows:
1. Tilt the machine backward and remove the bed lid by
removing the screw and sliding it to the left. (sec. 3-5)
2. Check that the guide-lines on the lower shaft and feed
cam should be aligned. (fig. 6-1)
If it is not so, adjust as follows.
3. Loosen the two screws (a) on the feed cam with a
hexagon socket screw key (2 mm).
Hold the feed cam with a screw key and turn the
handwheel either direction until the guide lines on the
lower shaft and feed cam are aligned.
4. Tighten the screws (a).
Next, check the timing of the up-down movements.
5. Turn the handwheel toward you until the needle comes
to its lowest position.
At this time, the guide-line on the feed rock cam should
be coming to its lowest point. (fig. 6-2)
If not, adjust as follows:
6. Remove the base.
Loosen the two screws (b) on the belt pulley with a
hexagon socket screw key (2 mm). (fig. 6-3)
7. Turn the lower shaft so that the guide line comes to its
lowest point.
At this point, hold the lower shaft with a pair of pincers
not to retate and turn the handwheel until the needle
comes to its lowest position.
8. Tighten the two screws (b).
9. When you have adjusted the timing of up-down
movement, check the timing of hook again. (sec. 3)
Guide Line
Guide Line

fig. 7-1
fig. 7-2
ab c
fig. 7-3
d
fig. 8-1
fig. 8-2 fig. 8-3
fig. 8-4
A,B A
BA
B
- 10 -
7. ADJUSTINGTHE FORWARD
AND REVERSE STITCH
When stretch stitch sewing, the lengths of the forward and
reverse stitches should be the same. check as follows:
1. Set the forward-reverse adjusting knob to the center “-”
mark.
2. Turn on the power switch with pressing the both of
stitch legth button (+ & -).
Machine will select the pattern to check the stretch
stitch. (fig. 7-1)
Attach the regular foot and set a sheet of paper under
the foot. Set the speed control button to maximum.
Start the machine and check the hole on the paper.
If the hole (A) and (B) are not at one, adjust as follows.
(fig. 7-2)
3. Tilt the machine backward and remove the base.
4. The forward-reverse sitich length is adjusted by turning
the screw (d). (fig. 7-3)
- If the forward stitch is finer than the reverse stitch,
turn the screw to the right. (fig.7-2-b)
- If the reverse stitch is finer than the forward stitch,
turn the screw to the left. (fig. 7-2-c)
NOTE: Do not loosen the nut out of the screw.
8. BOBBINWINDER
If bobbin winds unevenly, adjust as follows:
1. Remove the cap on backside of arm.
2. Loosen (not remove) the screw which is holding the
bobbin winder. (fig. 8-1)
- If bobbin winds as shown on fig. 8-2, tilt the bobbin
winder slightly to the left.
- If bobbin winds as shown on fig. 8-3, tilt the bobbin
winder slightly to the right.
3. Tighten the screw securely and re-set the cap.
If the bobbin thread is wound too little or too much, adjust
as follows.
4. Loosen the center screw of bobbin winder stop. (fig. 8-
4)
- If the bobbin thread is wound too little, turn the bobbin
winder stop slightly counter-clockwise.
- If the bobbin thread is wound too much, turn the
bobbin winder stop slightly clockwise.
5. Tighten the screw.

fig. 9
a
5.5 mm
fig. 10-1
fig. 10-2
a
- 11 -
9. HEIGHT AND DIRECTION OF
PRESSER FOOT
The height of the presser foot from the needle plate
should be 5.5 mm when it is lifted up. (fig. 9)
The presser foot should be facing frontward (the edge of
foot is parallel with the feed dog slot on needle plate).
If adjustment is needed, follow these procedures:
1. Remove the light cover.
2. Raise the presser foot lifter.
3. Loosen the screw (a).
Adjust the height and direction of presser foot.
4. Tighten the screw (a).
5. Check if the presser foot lifter has a slight play in down
position.
10. HEIGHT OF NEEDLE
THREADER
If the height of needle threader is not correct, the hook on
therader will not enter the needle eye. Adjsut as follows:
1. Remover the light cover.
2. Set the pattern number at “1” (straight stitch on left
needle position).
3. Raise the needle to its highest point by turning the
handwheel.
4. Loosen the screw on the needle threader bar stopper
with a hexagon socket screw key (1.5 mm). (fig. 10-1)
5. Adjust the height of stopper so that the hook enter the
needle eye.
6. Tighten the screw and check the height of needle
threader again.
• If the hook has bent, change the threader hook
assembly. To remove the hook assembly, pull it
downward. (fig. 10-2)

a
fig. 12
a
fig. 13 a
- 12 -
11. ZIGZAGTIMING • NEEDLE
STOP POSITION
The zigzag timing and the needle stop position when
start/stop switch is pressed are controlled by the
computer system. However, the needle bar position
(upper shaft revolution angle) is detected by the sensor
slit.
Therefore, if the slit is not correct position, the timing and
stop position will be incorrect. Adjust as follows:
1. Remove the front cover.
2. Loosen the screw (a) on the timing slit with a hexagon
socket screw key (1.5 mm). (fig. 11)
Align the guide-lines on the upper shaft and left side of
slit.
At this adjustment, do not move the slit side-ways.
3. Tighten the screw (a).
12. MOTOR BELTTENSION
If the motor belt tension is too tight or too loose, machine
will not run smoothly.
Adjust as follows:
1. Remove the front cover.
2. Loosen the screw (a). (fig. 12)
3. Push the pulley towards the belt so that the belt should
have flexibility of 5-6 mm when average pressure is
applied on its side.
4. Tighten the screw (a).
13.TIMING BELTTENSION
If the timing belt is too tight or too loose, the machine will
run heavily or the timing of hook and feed motion will be
changed incorrectly.
Adjust as follows:
1. Remove the front cover.
2. Loosen the screw (a). (fig. 13)
3. Push the pulley towards the belt and tighten screw.
The belt tension should have a flexibility of 4-5 mm
when average pressure is applied to its side.
When you have adjusted the timing belt tension, recheck
the timing of the feed motion (sec. 6) and the timing of the
hook (sec. 3 ) again.
fig. 11 View from lowerside

fig. 14-1
fig. 14-2
ab
0-0.5 mm
fig. 15
a
fig. 16
a
- 13 -
14. BACKLASH OF HOOK GEAR
If there is too much play on the hook gear on the turning
direction, it may be the cause for machine not to sew
properly and/or making excessive sewing noise.
1. Remove the needle plate and bobbin holder.
2. Tilt the machine backward and remove the bed lid by
removing the screw and sliding it to the left. (fig. 3-2)
3. Loosen the 3 screws (a) and move hook base (b) up or
down. (fig. 14-1)
4. Re-tighten the screws (a) tentatively and check follows.
• Free play at the tip of hook may be 0-0.5 mm. (fig. 14-
2)
• Attach the needle plate and check that the feed dog
does not touch the needle plate.
If touching, rotate the base (b) slightly.
5. Tighten the screws (a) securely.
When you have adjusted the backlash of hook gear,
check the timing of the hook again. (sec. 3)
15. UPPERTHREADTENSION
UNIT
The upper thread tension regulator unit has been
adjusted to the best sewing conditions at the position “4”.
However, if you wish to change this, do it as follows.
1. Remove the light cover.
2. Adjust the tension by turning the tension regulator
screw (a) that is located on the side of the machine
either to the left or right. (fig. 15)
For a stronger tension, turn screw towards the right
and for a weaker tension, turn screw to the left.
16. ADJUSTINGTHE LOWER
THREADTENSION
The bobbin thread tension is correctly adjusted at the
factory and normally it would not be necessary for you to
make adjustments yourself. If adjustments are necessary,
to obtain a weaker bobbin thread tension, turn the screw
(a) which is located on the front part of bobbin case
counter clockwise, and for a stronger tension, turn screw
clockwise. (fig. 16)

fig. I
fig. II
a
b
c
d
e
a
- 14 -
LOCATINGTHE DEFFECTED
ELECTRICAL PART
The self-diagnostic program
This machine is provided with the self-diagnostic program
for electrical parts.
If the machine does not function normally, although the
mechanical setting has been completed, check the
electrical parts by this program.
TO RUN THE SELF-DIAGNOSTIC PROGRAM
1. Trun off the power switch.
2. With pressing the both stitch length and width “+”
button, turn on the power switch. (fig. I)
3. When this program has started correctly, the LCD will
indicate the machine icon and version number of this
program. (fig. I)
When buttons are released, the LCD will change to
indicate the Frequency of power line. (fig. II-a)
4. By pressing any button, the mode of this program will
change and repeat as follow steps. (fig. II)
a. Frequency of power line.
b. Condition of switches and sesors
c. Phase of feed pulse motor
d. Phase of zigzag pulse motor
e. Condition of foot controller and speed control lever
5. To quit this program, turn off the power switch.
HOWTO CHECK
a. Frequency of power line
The frequency of connected power line will be indicated.
(50 or 60 Hz)

b
0
0
1
1
B
F W
01
01
O
0
1
- 15 -
b. Condition of switches and
sensors
The condition of each switch and sensor is indicated as
follows.
BH f: Buttonhole lever switch -Front
1=Neutral 0=Lever is pushed.
BH b: Buttonhole lever switch -Back
1=Neutral 0=Lever is pulled.
Lower the buttonhole lever and check these switches by
pushing or pulling this lever.
Also, using this mode, you can adjust the buttonhole lever
position. See next page “b-1 Adjustments for buttonhole
lever position”.
S: Stop sensor 1=not intercepted 0=intercepted
T: Timing sensor 1=not intercepted 0=intercepted
s: Speed sensor 1=not intercepted 0=intercepted
These sensors are intercepted by the slit plates on the
main shaft.
Stop sensor = Stop slit, Timing sensor = Timing slit,
Speed sensor = Speed slit
Turn the handwheel and check the response of each
sensor.
B: Sensor of needle bar position
1=not intercepted 0=intercepted (left needle position)
This sensor is intercepted by the lever of gear on the
zigzag pulse motor shaft.
Move the needle bar right or left and check the response
of this sensor.
F: Feed sensor
1=not intercepted 0=intercepted (feed dog is coming
most frontward)
This sensor is intercepted by the lever of gear on the feed
pulse motor shaft.
Remove the base and turn this pulley to check the
response of this sensor.
W: Bobbin winder switch
1=Bobbin winder spindle is in right position
0=Spindle is left position
Move the bobbin winder spindle left or right and check
this switch.
O: Presser foot switch
1=Presser foot is lowered, 0=Presser foot is lifted
Lower or lift the presser foot lifter and check the response
of this switch.
Buttonhole lever switch -Front
Buttonhole lever switch -Back
Stop sensor
Timing sensor
Speed sensor
Sensor of needle bar position
Feed sensor
Bobbin winder switch
Presser foot switch
Stop slit
Timing slit
Speed slit
Sensor
Main shaft
Sensor Gear
Sensor
Gear

fig. b-1a
fig. b-1b
0
fig. b-1c
fig. b-1d
a
b
- 16 -
b-1. Adjustment for buttonhole
lever position
If the machine does not sew even with the buttonhole
lever all the way down, it means that the buttonhole lever
is not positioned properly. Also, if the buttonhole lever is
not positioned properly, the machine will sew buttonhole
as fig. b-1a.
1. Run the self-diagnostic program and set the mode to
check the condition of switches and sesors.
2. Attach the buttonhole foot.
3. Lower the presser foot and the buttonhole lever.
4. Pull the presser foot frame towards you about 1 cm
while lifting the presser foot lifter slightly. Then slowly
move frame back again. Lower the lifter when BH f
changes to 0.
5. At this time, the presser foot frame should be about 1
mm forward from the extreme end.
If it is not correct position, adjust as follows:
6. Pull the presser foot frame 1 mm forward from the
extreme end, and lower the presser foot.
7. Remove the light cover.
8. Loosen the set screws (a, b). (fig b-1d)
9. Use the screw (a) as a pivot and pull the circuit board
towards you.
10. Tighten screw (b) when BH f changes from 1 to 0 and
while slowly pushing the circuit board backwards.
11. Tighten screw (a) and replace the light cover.
Re-check the buttonhole lever position when adjustments
have been completed.
Pull about 1 cm
Slowly move back
About 1 mm
Circuit board

c
d
e
a
b
c
- 17 -
c. Phase of feed pulse motor
When you have selected this mode, feed pulse motor will
move slightly and stop at the position which the lever of
gear intercept the feed sensor.
Normally, the number 2 or 4 or 6 will appear on the LCD.
If it was not so, loosen the screw of gear and rotate it
slightly. Re-tighten the screw and check the phase again.
d. Phase of zigzag pulse motor
When you have selected this mode, zigzag pulse motor
will move slightly and stop at the position which the lever
of gear intercept the needle bar sensor.
Normally, the number 2 or 4 or 6 will appear on the LCD.
If it is not so, loosen the screw of pulley and rotate it
slightly. Re-tighten the screw and check the phase again.
e. Condition of foot controller and
speed control lever
The condition of foot controller is indicated on the first line
of LCD.
Foot controller is not connected : the number 255 will
appear.
Connect the foot controller: the number will change to 74.
Press the pedal of controller: the number will decrease
according to the pressure on the pedal. When pressed
maximam, the number 0 will be indicated.
The condition of speed cotrol lever is indicated on the
lower line of LCD.
The number will change from 0 to 255 by sliding the lever
to the right.
WARNING MESSAGES ON LCD
When you turn on the power, if control buttons are not
released original position, machine will indicate the
warning message on the LCD.
a. Start/stop button is not released.
b. Reverse button is not released.
c. Needle up/down button is not released.
Check each button and switch which is located inside of
each button.
Condition of foot controller
Condition of speed contol lever

- 18 -
TROUBLE SHOOTING OF ELECTRICAL PARTS
Needle does not stop at up position Check the Stop sensor by
Self diagnostic program Exchange the STS sensor board Exchange the CPU
circuit board
Machine stops after a few stitches Check the Timing sensor by
Self diagnostic program Exchange the ST sensor board Exchange the CPU
circuit board
Warning is appeared Check the Feed sensor by
Self diagnostic program Exchange the Feed Sensor board Exchange the Feed
pulse motor
Warning is appeared Check the Zigzag sensor by
Self diagnostic program Exchange the Zigzag sensor board Exchange the
Zigazg pulse motor
Machine will start although the presser foot is lifted Check the Presser foot switch
by Self diagnostic program Exchange the Presser foot switch Exchange the CPU
circuit board
Bobbin wind icon is appeared although the Bobbin winder spindle is pushed to the left. Check the Bobbin winder switch
by Self diagnostic program Exchange the Bobbin winder switch Exchange the CPU
circuit board
At buttonhole sewing, machine will not start. Check the Buttonhole lever switch
by Self diognostic program Exchange the Buttonhole lever switch Exchange the CPU
circuit board
Machine runs high speed Check the Timing sensor by
Self diagnostic program Exchange the Speed sensor board Exchange the CPU
circuit board
Check the Fuse on the CPU circuit board
Exchange the fuse Check the Fuse on the CPU circuit board
Exchange the fuse
OK
NG OK NG
OK NG
OK
NG
OK
NG
OK
NG
OK
NG
OK
NG
NG
NG
OK
OK

- 19 -
Machine does not run at all Check the Fuse on
Speed control board Check the Codes and Connectors
connected to the Speed control board Check the Fuse on the
CPU circuit board
Motor does not run
Is the electrical sound played when Start/Stop button is pressed?
Exchange the fuse Exchange the damaged
code or connector Exchange the fuse
Exchange the Speed control board Exchange the CPU
circuit board
Exchange the motor Exchange the CPU
circuit board
Exchange the Control button circuit board
LCD does not indicate Exchange the
LCD board Exchange the CPU
circuit board
Can not control sewing speed by Speed control lever Check the condition of the Speed
control lever by Self diagnostic program Exchange the Speed control lever board Exchange the CPU
circuit board
Can not control sewing speed by Foot controller Check the condition of the Foot
controller by Self diagnostic program Exchange the foot controller Exchange the Speed
control board Exchange the CPU
circuit board
Warning is appeared
Exchange the CPU circuit board
Exchange the Control button circuit board
Warning is appeared Warning is appeared
OK
NG
OK NG NG
NG
NG
NO
OK NG NG
OK
NG
OK
NG NG
OK OK