Brother S-7200B, MD-741B, MD-751B, MD-741C, MD-751C Service Manual

S-7200B

(MD-741B, 751B, 741C, 751C)

Please read this manual before making any adjustments.

SINGLE NEEDLE DIRECT DRIVE STRAIGHT LOCK STITCHER WITH THREAD TRIMMER

SERVICE MANUAL

S-7200B

This service manual is intended for S-7200B; be sure to read the S-7200B instruction manual before this manual.

Carefully read the “SAFETY INSTRUCTIONS” and the whole of this manual to understand this product before you start maintenance.

As a result of research and improvements regarding this product, some details of this manual may not be the same as those for the product you purchased. If you have any questions regarding this product, please contact a Brother dealer.

S-7200B

i

SAFETY INSTRUCTIONS

[1] Safety indications and their meanings

This service manual and the indications and symbols that are used on the machine itself are provided in order to ensure safe operation of this machine and to prevent accidents and injury to yourself or other people. The meanings of these indications and symbols are given below.

Indications

DANGER

The instructions which follow this term indicate situations where failure to follow the instructions will result in death or serious injury.

CAUTION

The instructions which follow this term indicate situations where failure to follow the instructions could cause injury when using the machine or physical damage to equipment and surroundings.

Symbols

· · · · ·

This symbol ( ) indicates something that you should be careful of. The picture inside the triangle indicates the nature of the caution that must be taken. (For example, the symbol at left means “beware of injury”.)

· · · · ·

This symbol ( ) indicates something that you must not do.

· · · · ·

This symbol ( ) indicates something that you must do. The picture inside the circle indicates the nature of the thing that must be done. (For example, the symbol at left means “you must make the ground connection”.)

S-7200B

ii

[2] Notes on safety

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

CAUTION

Environmental requirements

Use the sewing machine in an area which is free from sources of strong electrical noise such as electrical line noise or static electric noise. Sources of strong electrical noise may cause problems with correct operation.

Any fluctuations in the power supply voltage should be within ±10% of the rated voltage for the machine. Voltage fluctuations which are greater than this may cause problems with correct operation.

The power supply capacity should be greater than the requirements for the sewing machine's power consumption. Insufficient power supply capacity may cause problems with correct operation.

The ambient temperature should be within the range of 5°C to 35°C during use. Temperatures which are lower or higher than this may cause problems with correct operation.

The relative humidity should be within the range of 45% to 85% during use, and no dew formation should occur in any devices. Excessively dry or humid environments and dew formation may cause problems with correct operation.

In the event of an electrical storm, turn off the power and disconnect the power cord from the wall outlet. Lightning may cause problems with correct operation.

Installation

Machine installation should only be carried out by a qualified technician.

Contact your Brother dealer or a qualified electrician for any electrical work that may need to be done.

The sewing machine weighs more than 44 kg. The installation should be carried out by two or more people.

Do not connent the power cord until installation is complete. The machine may operate if the treadle is depressed by mistake, which could result in injury.

Turn off the power switch before inserting or removing the plug, otherwise damage to the control box could result.

Be sure to connect the ground. If the ground connection is not secure, you run a high risk of receiving a serious electric shock, and problems with correct operation may also occur.

When securing the cords, do not bend the cords excessively or fasten them too hard with staples, otherwise there is the danger that fire or electric shocks could occur.

If using a work table which has casters, the casters should be secured in such a way so that they cannot move.

Use both hands to 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.

Be sure to wear protective goggles and gloves when handling the lubricating oil and grease, so that they do not get into your eyes or onto your skin, otherwise inflammation can result. Furthermore, do not drink the oil or eat the grease under any circumstances, as they can cause vomiting and diarrhea. Keep the oil out of the reach of children.

S-7200B

iii

CAUTION

Sewing

This sewing machine should only be used by operators who have received the necessary training in safe use beforehand.

The sewing machine should not be used for any applications other than sewing.

Be sure to wear protective goggles when using the machine. If goggles are not worn, there is the danger that if a needle breaks, parts of the broken needle may enter your eyes and injury may result.

Turn off the power switch at the following times. The machine may operate if the treadle is depressed by mistake, which could result in injury.

 When threading the needle  When replacing the bobbin and needle  When not using the machine and when leaving

the machine unattended

If using a work table which has casters, the casters should be secured in such a way so that they cannot move.

Attach all safety devices before using the sewing machine. If the machine is used without these devices attached, injury may result.

Do not touch any of the moving parts or press any objects against the machine while sewing, as this may result in personal injury or damage to the machine.

Use both hands to 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.

If an error occurs in machine, or if abnormal noises or smells are noticed, immediately turn off the power switch. Then contact your nearest Brother dealer or a qualified technician.

If the machine develops a problem, contact your nearest Brother dealer or a qualified technician.

Cleaning

Turn off the power switch before carrying out cleaning. The machine may operate if the treadle is depressed by mistake, which could result in injury.

Use both hands to 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.

Be sure to wear protective goggles and gloves when handling the lubricating oil and grease, so that they do not get into your eyes or onto your skin, otherwise inflammation can result. Furthermore, do not drink the oil or eat the grease under any circumstances, as they can cause vomiting and diarrhea. Keep the oil out of the reach of children.

Use only the proper replacement parts as specified by Brother.

Maintenance and inspection

Disassembly, assembly, maintenance and inspection of the sewing machine should only be carried out by a qualified technician.

Ask your Brother dealer or a qualified electrician to carry out any maintenance and inspection of the electrical system.

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

Turn off the power switch before inserting or removing the plug, otherwise damage to the control box could result.

If the power switch needs to be left on when carrying out some adjustment, be extremely careful to observe all safety precautions.

Use both hands to 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.

Use only the proper replacement parts as specified by Brother.

If any safety devices have been removed, be absolutely sure to re-install them to their original positions and check that they operate correctly before using the machine.

Any problems in machine operation which result from unauthorized modifications to the machine will not be covered by the warranty.

S-7200B

iv

[3] Warning labels

The following warning labels appear on the sewing machine. Please follow the instructions on the labels at all times when using the machine. If the labels have been removed or are difficult to read, please contact your nearest Brother dealer.

1

2

3

Be sure to connect the ground. If the ground connection is not secure, you run a high risk of receiving a serious electric shock, and problems with correct operation may also occur.

Safety devices: (A) Finger guard (B) Thread take-up cover

4

Direction of operation

3629M

Control box

Oil pan

S-7200B

CONTENTS

1. MACHINE SPECIFICATIONS............... 1

2. NOTES ON HANDLING........................ 2

3. FUNCTION SETTINGS

(OPERATION PANEL) ......................... 3

3-1. Maximum sewing speed and start backtack sewing

speed setting methods .......................................... 3

3-2. Using the LOCK key ................................................ 4

3-3. Setting the DIP switches .......................................... 4

3-4. Setting functions ...................................................... 5

3-5. Function List ............................................................ 6

3-6. Clearing saved data (Initialization) ........................... 21

4. INITIALIZING THE CONTROL

BOX PANEL .........................................22

5. ADJUSTING THE ROTARY HOOK

LUBRICATION AMOUNT

(-[]0[], []3[] specifications)..................23

6. ADJUSTMENTS ...................................24

6-1.

Adjusting the actuator position ................................. 24

6-2. Adjusting the safety switch position.......................... 25

6-3. Adjusting the thread take-up spring ......................... 26

6-4. Adjusting arm thread guide R................................... 27

6-5. Adjusting the presser foot height.............................. 27

6-6. Adjusting of the feed dog height............................... 28

6-7. Adjusting the feed dog angle.................................... 29

6-8. Adjusting the needle bar height................................ 30

6-9. Adjusting the needle and feed mechanism timing.... 30

6-10. Adjusting the needle and rotary hook timing.......... 31

6-11. Adjusting the thread trimming timing...................... 32

6-12. Adjusting the thread take-up amount

(-[][]3 specifications) ............................................. 33

6-13. Adjusting the needle up stop position

(When using the operation panel).......................... 34

6-14. Setting the needle up stop position and needle down

stop position (

If using the control box panel)

............. 35

6-15. Adjusting the treadle .............................................. 37

6-16. Adjusting the presser foot floating amount (minute

lifting amount) ........................................................ 37

7. REPLACING PARTS............................38

7-1. Fixed knife................................................................ 38

7-2. Movable knife........................................................... 38

7-3. Motor and timing belt................................................ 39

7-4. Rotary hook RP........................................................ 42

7-5. Feed bar shaft, Lifting feed shaft.............................. 43

8. APPLYING GREASE

(-[]3[], []5[] specifications)..................

44

8-1. When using the operation panel............................... 44

8-2. When using the control box panel ............................ 46

9. CONTROL SYSTEM............................. 48

10. CONTROL BOX AND MOTOR...........49

10-1. Removing and installing the control box ................ 49

10-2. Control box and motor rating plate......................... 50

10-3. Control circuit board............................................... 52

10-4. Checking the motor and power supply................... 54

10-5. Checking the solenoids.......................................... 55

11. TREADLE UNIT ASSEMBLY ............. 56

11-1. Types ..................................................................... 56

11-2. Standard setting values ......................................... 57

11-3. Setting method for standard depression

strokes ................................................................... 58

12. STANDING OPERATION PEDAL ......62

12-1.

Installing the foot plug ............................................ 62

12-2. Connectors ............................................................ 63

13. TROUBLESHOOTING........................ 64

13-1.

Sewing ................................................................... 64

13-2. Error code displays ................................................ 69

14. SEGMENT DISPLAY DEFINITION

TABLE................................................74

S-7200B

1. MACHINE SPECIFICATIONS

1

1. MACHINE SPECIFICATIONS

3 4 Quick reverse O O Thread wiper - O

0 3 5

Lubrication type Minimum lubrication Semi dry Complete dry

S 3 5 Use For light-weight

and difficult-to-sew

materials

For medium-

weight materials

For heavy-weight

materials

-33S, -43S

-45S

-453

-303, -403

-333, -433

-305

-405 Max. sewing speed 4,000 rpm 5,000 rpm* 4,500 rpm* Start backtacking and continuous backtacking speed

220 - 3,000 rpm

End backtacking speed 1,800 rpm Max. stitch length 4.2 mm 5 mm

Lifting lever 6 mm Presser foot

height

Knee lifter 16 mm Feed dog height 0.8 mm 1.2 mm Needle (DB×1, DP×5)

NS #9 - #11 #11 - #18 #19 - #22 Motor AC servo motor (4-pole, 450W) Control circuit Microprocessor

*…When sewing at speeds of 4,000 rpm or higher, set the stitch length to 4.2 mm or less.

Rotary hook

-33S

-43S

-303, -403

-333, -433

-305

-405

-45S

-453

Lubricated /

for light materials

Lubricated /

for medium materials

Lubricated /

for heavy materials

Rotary hook RP

(lubrication-free rotary hook)

Lubricating oil

-30[], -40[] -33[], -43[] -45[] Rotary hook High-speed spindle Needle bar

High-speed spindle

Special Brother grease Special Brother grease

S-7200B

2. NOTES ON HANDLING

2

2. NOTES ON HANDLING

About the machine set-up location

・ Do not set up this sewing machine near other equipment such as

televisions, radios or cordless telephones, otherwise such equipment may be affected by electronic interference from the sewing machine.

・ The sewing machine should be plugged directly into an AC wall

outlet. Operation problems may result if extension cords are used.

Carrying the machine

・ The machine should be carried by the arm by two people as

shown in the illustration.

* Hold the motor cover (A) by hand also so that the pulley does

not rotate.

Tilting back the machine head

・ Hold section (B) with your foot so that the table does not move,

and then push the arm with both hands to tilt back the machine head.

Returning the machine head to the upright position

1. Clear away any tools, etc. which may be near the table holes.

2. While holding the face plate with your left hand, gently return the

machine head to the upright position with your right hand.

2086M

2087M

2088M

2089M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

3

3. FUNCTION SETTINGS (OPERATION PANEL)

3-1.

Maximum sewing speed and start backtack sewing speed setting methods

If the LOCK key icon (1) is on, release the lock before carrying out the following operations.

1

・ The main display will change from an orange display to a

green display.

2

・ The maximum sewing speed can be set to a speed from 220

rpm to the maximum sewing speed that has been set for the head detector unit.

・ If all numbers in the sewing speed control display (2) are

illuminated, sewing will be carried out at the maximum speed that is set here when the treadle is fully depressed.

3

・ The start backtack sewing speed can be set to a speed from

220 rpm to 3,000 rpm. (The factory default setting is 1,800 rpm.)

4

・ When sewing starts, the sewing speed display disappears

and returns to the orange display.

NOTE:

When the main display is green, normal key operations such as the start backtack key and the fixed stitch key cannot be used. Press the MAX key once more to clear the sewing speed display and return to the orange display. Normal key operations can then be carried out.

Maximum sewing speed setting

Start backtack sewing speed setting

2233M

2236M

2159M

2232M

Maximum sewing speed Start backtack sewing speed

(Current setting)

2234M

2235M

Example:

4,500 rpm

Example:

1,600 rpm

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

4

3-2. Using the LOCK key

When the power switch is turned on, the LOCK key (1) turns on. (The icon (2) is illuminated.) The key operation that has been set using Function No. 101 will be disabled in order to prevent the accidental changing of settings.

Refer to “3-5. Function List” (P.17) for the available settings for Function No. 101.

Press down the LOCK key (1) for 2 seconds or more. The icon (2) will switch off and the lock will be released.

When the icon (2) is switched off, press down the LOCK key (1) for 2 seconds or more. The icon (2) will illuminate and the key operation that has been set using Function No. 101 will be disabled.

3-3. Setting the DIP switches

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

ON Presser foot is lowered. (Export specification)

1

Presser foot position when the treadle is returned to the neutral position after thread trimming

OFF

Presser foot is kept raised. (Japanese specification only) (See NOTE 1.)

ON Enabled

2

Presser foot lowering when the treadle is depressed to step 1. (See NOTE 2)

OFF Disabled ON The lock will not be released even if the LOCK key is pressed.

3 Disabling the LOCK key

OFF

Enabling or disabling of the key operation that has been set using Function No. 101 can be selected using the LOCK key.

4 Always set to off. (See NOTE 3.)

(NOTE 1) Once the knee lifter switch is used to lower the presser foot, the treadle can not be used to raise the presser foot

while the machine is stopped; at this time, only the knee lifter is able to raise and lower the presser foot. (NOTE 2) The treadle unit should also be adjusted when using this function. (Refer to page 56.) (NOTE 3) When set to ON, treadle operation is disabled, so it should always be left at OFF. If set to ON, the messages “ 「 ” (green) and “ ” (orange) will flash alternately in the

display.

1230B

Control Box

0655B

Control box

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

5

3-4. Setting functions

・ If the LOCK key icon (1) is on, release the lock before carrying out the following

operations.

・ If the MAX key icon (2) is on, press the MAX key to return the main display to stitch

number display (orange).

1

・ The main display will change to green and function setting

mode will be enabled.

2

・ Refer to the “Function List” to select the number for the

function that you would like to change the setting for.

3

・ Refer to the “Function List” to change the setting to a value

within the setting range.

4

・ The buzzer will sound for approximately 1 second, and then

the setting will be accepted.

・ The main display will return to the stitch number display

(orange).

(Press for 2 seconds or more)

NOTE:

・ If you depress the treadle before pressing the ENTER key, the main display will return to orange and the setting value

will not be changed.

・ If you change the function number after changing the setting value but before pressing the ENTER key, the setting

value will not be changed. You need to press the ENTER key for each function number for the setting to be accepted.

Selecting the function number

Changing the setting value

2240M

2241M

2242M

2239M

2238M

Function no. Setting value

Example:

Function

no.14

Example:

Setting value

1

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

6

Becomes higher Becomes lower

Becomes lower Becomes higher

3-5. Function List

Function No. 0 − 15

No. Initial value Setting range Setting details

0 0 (degrees)

-10 – 20

(degrees)

Needle up stop position setting

1 0 (degrees)

-10 – 10

(degrees)

Needle down stop position setting

2 0

0 – 1

Depressing forward when depressed backward (thread trimming) 0: Disabled (depressing forward is enabled after returning to neutral position) 1: Enabled

3 1

0 – 1

Power supply voltage drop check (reset detection) function 0: Not used 1: Used; "Err 6" is displayed when a voltage drop occurs

4 0

0 – 1

Buzzer (electronic sound) for panel operation 0: Used 1: Not used

5 0

–

(Do not change this setting.)

6 0

0 – 1

Needle penetration up operation 0: Used 1: Not used

7 0

0 – 1

Backtack sewing speed 0: Limited by sewing speed control key 1: Not limited by sewing speed control key

9 0

0 – 1

End backtack sewing speed 0: Separate setting from start backtack sewing speed is possible 1: Setting for start backtack sewing is used

11

(NOTE 1)

0

0 – 4

Option actuator operation setting 0: Half stitch correction sewing 1: Single stitch correction sewing 2: Single reverse stitch correction sewing (reverse feed) 3: Thread trimming 4: Single end backtack cycle cancel 5: Solenoid-type presser foot lifter is raised (Alternating*) 6: Solenoid-type presser foot lifter is raised (Momentary*)

12 0

0 – 1

Presser foot status when treadle is returned to neutral after thread trimming 0: Presser foot drops (See NOTE 2) 1: Presser foot does not drop

13 0

0 – 1

Presser foot status after treadle stops at neutral 0: Presser foot does not lift 1: Presser foot lifts

14 0

0 – 1

Actuator function 0: Reverse stitch switch during operation, correction sewing switch when

stopped

1: Thread trimming switch

15 0

0 – 1

Slow stop control when treadle is returned to neutral 0: Slow stop control without step operation 1: Above control is not used

(NOTE 1) If function No. 69 is set to “3”, operation is enabled.

(NOTE 2) Presser foot will not drop if DIP switch 1 is set to OFF.

*… Enabled if the control box model is MD-741A/751A.

(Alternating): The presser foot is raised or lowered each time the optional actuator is pressed.

(Momentary): The presser foot is raised only while the optional actuator is being pressed.

2244M

2243M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

7

Function No. 16 − 28

No. Initial value Setting range Setting details

16 3 (minutes)

0 – 30

(minutes)

Overtime function 0: Not used 1–30: Machine stops after continuous operation for set time, and "Err 8" is

displayed.

17 0

0 – 2

Correction sewing function (See NOTE 3) 0: Half stitch correction sewing/Single stitch correction sewing 1: No correction sewing/Single stitch correction sewing 2: Reverse stitch (reverse feed) correction sewing/Single stitch correction

sewing

18 20 (ms)

10 – 200 (ms)

19 50 (ms)

10 – 200 (ms)

20 50 (ms)

10 – 200 (ms)

Thread wiping and presser foot lift operation timing after thread trimming

21 0

0 – 1

Start backtack sewing operation 0: Stitch number A, B (N stop) 1: Stitch number A, B, A, B (N stop double)

22 0

0 – 1

End backtack sewing operation 0: Stitch number C, D 1: Stitch number C, D, C, D (N stop double)

23

(NOTE 4)

0 (stitches)

0 – 99

(stitches)

Stitch number G

24

(NOTE 5)

0 (stitches)

0 – 99

(stitches)

Stitch number H

25

(NOTE 6)

0 (stitches)

0 – 99

(stitches)

Stitch number I

26 0

0 – 1

Speed for moving to end backtack 0: Decelerates to low speed, then end backtacking starts 1: Decelerates to end backtacking speed, then end backtacking starts

(Cycle time can be shortened.)

27 0

0 – 1

Continuous backtacking operation 0: Stitch number A, B, C, D 1: Stitch number A, B x D times

28 0

0 – 1

Feed direction when stopping immediately after start backtacking 0: Quick reverse solenoid turns off and stops in

normal feed direction

1: After stopping, quick reverse solenoid turns OFF

(See NOTE 7)

(NOTE 3) The setting to the left of the “ / ” symbol is when the correction stitch icon is off, and the setting to the right is when

the correction stitch icon is on.

Turn the power off and back on again when this setting is changed. The setting will be enabled after the power

turns back on.

(NOTE 4) Stitch number setting is enabled when Function No. 118 is set from “1” to “3”.

(NOTE 5) Stitch number setting is enabled when Function No. 118 is set to “2” or “3”.

(NOTE 6) Stitch number setting is enabled when Function No. 118 is set to “3”.

(NOTE 7) Operates when treadle is lightly pressed when Function No. 31 is set to “0”.

Motor

Thread wiping

Presser foot

lifting

(fully ON)

Needle up stop

2245M

2246M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

8

Function No. 29 − 40

No. Initial value Setting range Setting details

29* 0

0 – 3

Actuator function while sewing machine is stopped 0: None 1: Solenoid-type presser foot lifter is raised (alternating**) 2: Solenoid-type presser foot lifter is raised (momentary**) 3: Quick reverse mechanism operates

30

150

(ms)

0 – 500

(ms)

Delay time until motor starts operating when using automatic presser lifter and the presser foot is raised when sewing starts

31 0

0 – 1

Stopping during start backtacking and speed during start backtacking 0: When treadle is returned to neutral, start backtacking finishes and then

operation stops, and the speed is the start backtacking (constant) speed

1: When treadle is returned to neutral, stopping is possible while start

backtacking is in progress, and the start backtacking speed corresponds to the treadle depression amount (low speed up to start backtacking speed)

32 300 (ms)

10 − 990 (ms)

Presser foot lifter solenoid fully ON time

33 0

0 – 1

Operation during pleat sewing setting 0: Reverse sewing operation when actuator switch is ON 1: Fixed stitch sewing operation when actuator switch is ON

(fixed stitch sewing recall function)

34 0 or 1

0 – 1

[Do not change this setting]

35 0

0 – 1

Presser foot soft down mode 0: Automatic mode (See NOTE 8) 1: Manual mode (See NOTE 9)

36

180

(seconds)

(3 minutes)

0 – 240

(seconds)

Presser foot lift time 0: No timer function (does not drop) 1−240: Presser foot drops after set time

37 0

0 – 1

Automatic presser foot lifter type 0: Solenoid type (See NOTE 10) 1: Pneumatic type (See NOTE 11)

38

(NOTE 12)

40 (ms)

20 – 120 (ms)

Delay time for presser foot lifter solenoid to turn on after presser foot drop command

39

(NOTE 13)

12

10 – 12

Voltage detection constant for presser foot lifter solenoid to turn on after presser foot drop command

40 0

0 – 1

Operation after knee switch is used to raise and lower presser foot (See NOTE 14) 0: Presser foot cannot be raised and lowered by depressing the treadle

backward

1: Above operation is possible

(NOTE 8) Adjustment of Function No. 39 is necessary.

(NOTE 9) Adjustment of Function No. 38 is necessary.

(NOTE 10) Duty during chopping can be changed using Function No. 115.

(NOTE 11) Duty during chopping can be changed using Function No. 116.

(NOTE 12) Only enabled when Function No. 35 is set to “1”.

(NOTE 13) Only enabled when Function No. 35 is set to “0”. If set to “10”, response is fastest and operating noise is greatest.

(NOTE 14) Setting is only enabled when DIP switch 1 is set to OFF.

*… Enabled if the control box model is MD-741A/ 751A.

**… (Alternating): The presser foot is raised or lowered each time the optional actuator is pressed.

(Momentary): The presser foot is raised only while the optional actuator is being pressed.

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

9

Function No. 41 − 55

No. Initial value Setting range Setting details

41 0

0 – 1

Presser foot lifting when treadle is depressed backward to 1st step after returning to neutral 0: Possible 1: Not possible

42 0

0 – 1

Operation when treadle is depressed backward 0: Thread trimming operation 1: Thread trimming operation disabled (presser foot is raised when treadle is

depressed backward)

43 0

0 – 1

Depressed backward operation after treadle is returned to neutral and needle stops in the up position 0: Single stitch is sewn and then the thread is trimmed (lock stitchers) 1: Thread wiping operation when needle is stopped in up position (chain

stitchers)

44 0

0 – 1

Operation when Standing operation variable speed pedal is on 0: Sewing speed corresponds to treadle depression amount 1: Sewing speed corresponds to sewing speed control key setting (constant

speed)

45 80 (ms)

0 – 500 (ms)

Delay time from standing pedal turning on until motor starts operating

46 0

0 – 1

Operation during standing operation when AUTO function is on 0: Sewing pauses when presser foot lifter pedal is on (operation pause) 1: Above function is not used

47 0

0 – 1

Operation during standing operation when AUTO function is on 0: Operation stops when high speed pedal turns back on, and restarts when

off

1: Above function is not used

48 0

0 – 1

Thread trimming pedal function after thread trimming during standing operation 0: Presser foot can be raised and lowered 1: Above operation not used (only possible using presser foot lifter pedal)

49 0

0 – 1

Alternate standing operation pedal and treadle operation (See NOTE 15) 0: Treadle operation is disabled after standing operation pedal is used 1: Treadle operation can also be used after standing operation pedal is used

(alternate operation is possible)

50 4000 (rpm)

300 – 5000

(rpm)

Automatic deceleration speed when quick reverse mechanism has been operated using the actuator switch

51* 0

0 – 1

Correction stitch sewing using actuator switch after thread trimming 0: Not possible (switch operation disabled) 1: Possible

52 2 (needles)

1 – 99

(needles)

Number of slow start stitches

53*

10

(needles)

0 – 100

(needles)

Count units for stitch counter display 0: No counting operation 1–100: Display counts down by number of stitches set

54* 1

0 – 2

Operation when stitch counter warning occurs (“!” icon is illuminated) 0: Starting using treadle is enabled as normal 1: Starting using treadle is disabled (thread trimming by depressing treadle

backward is possible)

2: Starting using treadle is completely disabled once treadle is returned to

neutral and operation stops

55

(NOTE 16)

0

0 – 1

Operation after treadle is depressed backward or knee switch is operated when presser foot is raised 0: When treadle is returned to neutral, presser foot is raised 1: When treadle is returned to neutral, presser foot is lowered

(NOTE 15) Presser foot lifter pedal operation is not included. In the case of simultaneous operation, the standing operation

pedal takes priority.

(NOTE 16) Setting is only enabled when DIP switch 1 is set to ON.

*… Settings indicated with " * " are enabled when the power is turned off and then back on.

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

10

Function No. 56 − 60

No. Initial value Setting range Setting details

56 0

0 – 1

Function for preventing needle bar operation when treadle is accidentally depressed forward when it is returned to neutral after being depressed backward 0: Used 1: Not used

57

(NOTE 17)

0

0 – 1

Operation when treadle is depressed forward to 1st step when presser foot is raised 0: Presser foot is lowered 1: Presser foot is not lowered

58 2

0 – 2

Synchronization function when quick reverse mechanism has been operated using the actuator switch 0: Disabled 1: Only quick reverse mechanism synchronization enabled 2: Synchronization of main shaft at automatic deceleration speed set by No. 50

59 0 (degrees)

0 – 355

(degrees)

[Do not change this setting]

60

150

(degrees)

0 – 355

(degrees)

[Do not change this setting]

(NOTE 17) Setting is only enabled when DIP switch 2 is set to ON.

* Use Function No. 50 to set the automatic deceleration speed when the quick reverse mechanism has been operated using

the actuator switch.(Setting possible in units of 100 rpm)

* Use Function No. 58 to set the synchronization function when the quick reverse mechanism has been operated using the

actuator switch.

(Example) Default settings: At low speed: 0°; At high speed: 150°

Needle up stop point is home point

Direction of main shaft rotation

Operating angle range

Operating angle

(At low speed: No. 59)

(At high speed: No. 60)

0654B

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

11

Becomes lower Becomes higher

Function No. 61 − 68

No. Initial value Setting range Setting details

61 0

0 – 1

Highest needle position stop operation 0: Not used 1: Used

62

(NOTE 18)

0

0 – 1

Thread wiping operation during highest needle position stop operation 0: Thread wiping occurs after needle stops in highest position 1: Thread wiping occurs after thread trimming, and then needle bar is raised

63 0

0 – 1

Thread trimming timer operation 0: Not used (Thread trimming is off when needle bar is stopped at the up

position)

1: Used (Time is set using Function No. 73)

64 0

0 – 2

0: Standard 1: Not used 2: Twin needle lock stitcher (T-8422A-[][]3) [Do not change this setting]

65

(NOTE 18)

150 (ms)

10 – 500 (ms)

Delay time until reverse operation starts during highest needle position stop operation

66

(NOTE 18)

0

0 – 1

Presser foot lift timing during highest needle position stop operation 0: Presser foot is raised after needle bar is raised 1: Presser foot is raised before needle bar lift operation starts (See NOTE

19)

67

(NOTE 18)

0 (degrees)

-20 – 20

(degrees)

Highest needle position stop position setting

68

(NOTE 20)

0

0 – 1

Seam matching function during automatic backtacking 0: Operation does not stop when switching cloth feed direction 1: Operation momentarily stops when switching cloth feed direction

(NOTE 18) Setting is enabled when Function No. 61 is set to “1”.

(NOTE 19) Operation is disabled when Function No. 62 is set to “1”. Presser foot is raised after needle bar is raised.

(NOTE 20) Used when you would like to match the seam accurately during automatic backtacking. Use Function No. 78 to

set the stop position and Function No. 79 to change the time before restarting.

2248M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

12

Function No. 69

No. Initial value Setting range Setting details

69 0

0 – 3

Actuator (option) function 0: No function (1: Stitch counter actuator) 2: Sewing speed actuator 3: Option actuator

Connect the switches to connector CN11 on the control circuit board.

・ When the low speed switch is pressed, the sewing speed becomes 1,000 rpm. The speed can be changed by setting

Function No. 122.

・ When the medium speed switch is pressed, the sewing speed becomes 3,000 rpm. The speed can be changed by setting

Function No. 121.

・ When the high speed switch is pressed, the sewing speed returns to the maximum sewing speed that has been set using

the MAX key.

Connect to connector CN9 on the control circuit board.

・ Set the operation using Function No. 11.

High speed switch

Medium speed switch

Low speed switch

Option Actuator

2250M

2251M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

13

Function No. 70 − 72

No. Initial value Setting range Setting details

70

(NOTE 21)

6

0 – 6

Option output setting 0: Puller 1: Needle cooler (synchronized output during operation) 2: Air saving 3: Condense 4: Chain stitch thread trimming (thread wiping) 5: Pneumatic wiper 6: No output

71

(NOTE 22)

0 (needles)

0 – 99

(needles)

Number of stitches from sewing start until puller is lowered 0: Synchronized with presser foot lifter operation 1 − 99: Puller is lowered after the set number of stitches is sewn

72

(NOTE 22)

10

(seconds)

5 – 30

(seconds)

Time until puller is lowered

(NOTE 21) The factory default setting is for no output, so the output must be set. Output is from pins 2–4 of connector CN15

on the control circuit board.

(NOTE 22) Setting is enabled when Function No. 70 is set to “0”.

・ When the sewing machine is stopped, the puller is lowered after 10 seconds in synchronization with the automatic presser

foot lifter.

・ During sewing, the puller is only raised when the reverse mechanism operates.

・ The time of 10 seconds can be changed by setting Function No. 72.

・ Function No. 71 can be used to set the number of stitches until the puller is lowered after sewing starts. If the puller is

raised (in synchronization with the automatic presser foot lifter) while the sewing machine is stopped after thread trimming, this operation occurs.

・ Output is synchronized with motor operation.

・ Output only occurs at the sewing start and the sewing end. A material edge sensor (S2) is required for output at the

sewing end.

・ Function No. 108 is used to set the number of stitches at the sewing start. Output only occurs while the number of stitches

set are being sewed after sewing starts.

・ The number of stitches at the sewing end is set by fixed stitch number E at the operation panel. Output occurs when the

edge of the material is detected.

・ The delay time after thread trimming until output turns off is set using Function No. 112. If the needle stops in the down

position after the edge of the material is detected, output turns off when the needle stops.

Option

Moto

r

Moto

r

Material edge sensor signal

Option

Needle up signal

Fixed stitch number E

2252M

2253M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

14

・ Start backtacking or end backtacking must be set.

・ For the sewing start, set stitch number B to “0”. Output will occur while stitches for stitch number A are being sewn.

・ For the sewing end, set stitch number C to “0”. Output will occur while stitches for stitch number D are being sewn.

・ After thread trimming, the thread wiper signal is output.

・ Use Function No. 109 and No. 110 to set the timer operation.

・ After thread trimming, output is synchronized with the automatic presser foot lifter.

・ Use Function No. 111 and No. 112 to set the timer operation.

・ When the presser foot is lowered, option output turns off.

Moto

r

Option

Needle up stop

Motor

Needle up stop

Option

Presser foot lifting

Option

Needle up signal

Motor

Stop

Stitch

number A

Stitch number D

Operation

2254M

2255M

2256M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

15

Function No. 73 − 79

No. Initial value Setting range Setting details

73

(NOTE 23)

90 (ms)

50 – 150 (ms)

Thread trimming on time

74 15 degrees

-345 – 345 (degrees)

Quick reverse solenoid on timing during start backtacking/continuous backtacking

75 -30 degrees

-345 – 345 (degrees)

Quick reverse solenoid off timing during start backtacking/continuous backtacking

76 -30 degrees

-345 – 345 (degrees)

Quick reverse solenoid off timing during end backtacking

77

(NOTE 24)

15 degrees

-345 – 345 (degrees)

Quick reverse solenoid on timing during end backtacking

78

(NOTE 25)

180

(degrees)

0 – 350

(degrees)

Pause position when switching feed direction

79

(NOTE 26)

100 (ms)

10 – 500 (ms)

Pause time when switching feed direction

(NOTE 23) Setting is enabled when Function No. 63 is set to “1”.

(NOTE 24) Setting is enabled when Function No. 22 or No. 26 is set to “1”.

(NOTE 25) Setting is enabled when Function No. 68 is set to “1”. The stopping position is the angle after the need up signal

turns on.

(NOTE 26) Setting is enabled when Function No. 68 is set to “1”. The reverse feed mechanism switches at the stopping

position. When the stopping time has elapsed, the sewing machine restarts automatically.

・ If the values are set to values that are less than the initial value (- direction), the quick reverse solenoid on/off timing

becomes faster. If the seam length immediately before switching occurs is short, change the setting to a value in the direction.

・ If the values are set to values that are greater than the initial value (+ direction), the quick reverse solenoid on/off timing

becomes slower. If the seam length immediately after switching occurs is short, change the setting to a value in the + direction.

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

16

Function No.80 − 88

No. Initial value Setting range Setting details 80* 0

-7 – 7

Treadle backward on (thread trimming) point

81* 0

-5 – 5

Treadle backward 1st step on (presser foot lifting) point

82* 0

-5 – 5

Treadle forward 1st step on (presser foot dropping) point

83* 0

-5 – 5

Treadle forward on (starting) point

84* 0

-5 – 5

Treadle variable speed range starting point

85* 0

-6 – 6

Treadle high speed range reaching point

86* 0

-2 – 2

Variable speed range starting point for standing operation variable speed pedal

87* 0

-2 – 2

High speed range reaching point for standing operation variable speed pedal

88* 0

0 – 2

Treadle speed curve 0: Constant 1: Curves downward 2: Curves upward

*… Settings indicated with “ * ” are enabled when the power is turned off and then back on.

With the treadle neutral position as the 0 point, the values in the forward direction are + (plus) values, and those in the backward direction are - (minus) values, so that the speeds accelerate or decelerate around the standard setting. (Refer to page 57 for details.)

(ex. 1) Setting for Function No. 80

(ex. 2) Setting for Function No. 83

(ex. 3) Setting for Function No. 85

Speed

Depression stroke

De

p

ression stroke

Speed

Neutral

Depression stroke

Speed

Neutral

Depression stroke

Speed

Neutral

2257M

2258M

2260M

2259M

Treadle backward stroke

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

17

Function No. 90 − 107

No. Initial value Setting range Setting details

90

220

(rpm)

150 – 300

(rpm)

Thread trimming speed (TRIM)

91

220

(rpm)

150 – 300

(rpm)

Low speed (INCH)

92

1400

(rpm)

500 – 2,500

(rpm)

Stop improvement speed (POS) [Do not change this setting.]

93

700

(rpm)

INCH – 1,000

(rpm)

Slow speed (SLOW)

94

3,000 (rpm)

INCH – 3,000

(rpm)

Start backtacking limit speed (SBL) (See NOTE 27)

96

1,800 (rpm)

INCH – 3,000

(rpm)

End backtacking speed (EBT)

98

HIL

(rpm)

INCH – HIL

(rpm)

Automatic speed (AUTO)

99 (NOTE 28)

INCH – 5,000

(rpm)

Maximum sewing speed limit speed (HIL) (See NOTE 29)

101 1

0 – 3

Lock level for operation panel lock 0: FUNC key 1: FUNC key + MAX key 2: FUNC key + MAX key + Correction key 3: FUNC key + MAX key + Correction key + Stitch number key

102 0

–

[Do not change this setting]

103 0 (needles)

0 – 99

(needles)

No. of pocket sewing stitches J

104 0 (needles)

0 – 99

(needles)

No. of pocket sewing stitches K

105 0 (needles)

0 – 99

(needles)

No. of pocket sewing stitches L

106 0 (needles)

0 – 99

(needles)

No. of pocket sewing stitches M

107 0

–

[Do not change this setting]

(NOTE 27) This is the upper limit for the start backtacking speed setting. Refer to page 3 for details on start backtacking

speed settings.

(NOTE 28) This setting is read from the head detector unit.

(NOTE 29) This is the upper limit for the maximum sewing speed setting. Refer to page 3 for details on maximum sewing

speed settings.

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

18

Function No. 108 − 114

No. Initial value Setting range Setting details

108

(NOTE 30)

0 (needles)

0 – 99

(needles)

Number of stitches for option output (C1)

109

(NOTE 31)

10 (ms)

0 – 990 (ms)

Delay time until option output turns on (C2)

110

(NOTE 31)

0 (ms)

0 – 990 (ms)

Option output on time (C3)

111

(NOTE 32)

0 (ms)

0 – 990 (ms)

Delay time until option output turns on (C4)

112

(NOTE 33)

2000 (ms)

0 – 9900 (ms)

Option output on time (C5)

113

(NOTE 34)

0 (needles)

0 – 99

(needles)

Number of stitches for option output (C6)

114

(NOTE 34)

0 (needles)

0 – 99

(needles)

Number of stitches for option output (C7)

(NOTE 30) Setting is enabled when Function No. 70 is set to “2”.

(NOTE 31) Setting is enabled when Function No. 70 is set to “4”.

(NOTE 32) Setting is enabled when Function No. 70 is set to “5”.

(NOTE 33) Setting is enabled when Function No. 70 is set to “2” or “5”.

(NOTE 34) The stitch number control output signal can be set in accordance with the variable input signal.

The variable input signal should be connected to connector CN6. The output signal is sent to connector CN11.

NOTE: If Function No. 112 and No. 113 are set to “0”, output is synchronized with the variable input signal.

Moto

r

Variable input signal

Needle up signal

Output signal

External input

External output; signal is open collector output within maximum 10 mA

2262M

2263M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

19

Function No. 115 − 118

No. Initial value Setting range Setting details

115

(NOTE 35)

10

(1.0 ms)

1 – 49

0.1 – 4.9 (ms)

On time when solenoid-type presser lifter solenoid is chopping

116

(NOTE 36)

25

(2.5 ms)

1– 49

(0.1 – 4.9 ms)

On time when pneumatic-type presser lifter solenoid is chopping

117

11

(1.1 ms)

1 – 49

(0.1 − 4.9 ms)

On time when quick reverse solenoid is chopping

118

(NOTE 37)

0

0 – 6

Sewing pattern setting when name label key is on 0: E–F–E–F (Name label attaching) 1: E–F–E–F–G 2: E–F–G–H–H–G–F–E (Pocket sewing 1) 3: E–F–G–H–I–H–G–F–E (Pocket sewing 2) 4: E–F–G–H–I–I–H–G–F–E 5: E–F–G–H–I–J–I–H–G–F–E 6: E–F–G–

H–I–J–K–L–M

(NOTE 35) Setting is enabled when Function No. 37 is set to “0”.

(NOTE 36) Setting is enabled when Function No. 37 is set to “1”.

(NOTE 37) When set to “1”, stitch number G is set for function No. 23.

When set to “2”, stitch number G is set for function No. 23 and stitch number H is set for Function No. 24. When set to “3”, stitch number G is set for function No. 23, stitch number H is set for Function No. 24 and stitch number I is set for Function No. 25. This step is skipped if the number of stitches is zero.

Presser foot lifting

(fully ON)

Presser foot lifting

(fully ON)

Quick reverse solenoid

(fully ON)

2265M

2266M

2264M

2267M

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

20

Function No. 119 − 131

No. Initial value Setting range Setting details

119 3

–

[Do not change this setting.]

120 5

–

[Do not change this setting.]

121

(NOTE 38)

3000 (rpm)

200 – 5000

(rpm)

Speed when medium speed switch is on

122

(NOTE 38)

1000 (rpm)

200 – 5000

(rpm)

Speed when low speed switch is on

123

45

(degrees)

30 – 90

(degrees)

Servo lock release angle (Do not change this setting.)

124* 0

0 – 1

Material edge sensor logic selection 0: Detects material absent 1: Detects material present

125 0

0 – 1

Servo lock operation 0: None 1: When stopped 2: When presser foot lifting signal is on

126 1 (seconds)

0 – 120

(seconds)

Servo lock timer setting 0: No timer operation 1–120: Timer operates (1–120 seconds)

127 100

–

[Do not change this setting.]

128 0

0 – 3

Flicker reduction function (when flickering occurs from fluorescent light) 0: None 1: Medium flicker reduction 2: Low flicker reduction 3: High flicker reduction 4: [Do not use this setting, otherwise the motor will overheat.]

129 0

-2 – 2

Motor acceleration gain [Do not change this setting.]

130 0

-2 – 2

Motor deceleration gain [Do not change this setting.]

131

– –

[Do not change this setting.]

(NOTE 38) Setting is enabled when Function No. 69 is set to “2”.

*… Settings indicated with “ * “ are enabled when the power is turned off and then back on.

Function No.132 − 136

The following function numbers show maintenance information.

No. Description of displays 132 Cumulative power on time (Actual time = Displayed time x 10) 133 Cumulative operating time (Actual time = Displayed time xxxx x 10) 134 Cumulative grease-up running time (Time = Display xxxx x 1 hour) / Grease life estimate (%) 135 ROM version (x.xxx) 136 Set maximum speed history (rpm)

S-7200B

3. FUNCTION SETTINGS (OPERATION PANEL)

21

3-6. Clearing saved data (Initialization)

When saved data is cleared, the following data are returned to factory default settings. ・ All data that has been set using the operation panel (including function setting data)

Initializing all data

1. While pressing the RESET key on the operation panel, turn on the power switch. The main display will change to orange and “iniT ALL” will be displayed.

2. Press the ENTER key. Initialization will be carried out and the “iniT ALL” display will change to green.

3. After this, the operation panel and the treadle can be operated. When an operation is carried out, the display will return to the normal display.

Initializing only speed data

1. While pressing the MAX key on the operation panel, turn on the power switch. The main display will change to orange and “iniT rPM” will be displayed.

2. Press the ENTER key. The speed data will be initialized to the speed data from the head detector unit and the “iniT rPM” display will change to green.

3. After this, the operation panel and the treadle can be operated. When an operation is carried out, the display will return to the normal display.

Initializing only the function setting data

1. While pressing the FUNC key on the operation panel, turn on the power switch. The main display will change to orange and “iniT FunC” will be displayed.

2. Press the ENTER key. Initialization of the function setting data will be carried out and the “iniT FunC” display will change to green.

3. After this, the operation panel and the treadle can be operated. When an operation is carried out, the display will return to the normal display.

When the power is turned on for the first time, the treadle and the operation panel cannot be operated for a period of approximately 4 seconds. After approximately 4 seconds, the main display will change to green and “init rPM” will be displayed. “iniT rPM” means that the sewing machine's speed settings have been initialized. In addition, this display will also appear in the following cases approximately 4 seconds after the power has been turned on.

・ When the control box has been replaced

・ When a sewing machine with different speed specifications to the control box is connected

NOTE:

When the power switch is turned on, any of the sewing machine's sewing speeds that are different from the setting data in the head detector unit are reset automatically. When initialization is complete, the main display will change to green and “init rPM” will be displayed. After this, the operation panel and the treadle can be operated. When an operation is carried out, the display will return to the normal display.

S-7200B

4. INITIALIZING THE CONTROL BOX PANEL

22

4. INITIALIZING THE CONTROL BOX PANEL

This returns the control box panel settings to the factory default settings.

NOTE:

The control box panel will not operate when the machine head operation panel is connected.

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

1

Set DIP switch -3 to OFF.

(This will cancel the lock so that the functions can be set.)

2

While pressing the end backtack key (1), press the power switch (2) to turn on the power.

3

1. Press the start backtack key (3) so that “r” is displayed in

the top row of the stitch number display.

2.

Press the end backtack key (1) to set the value in the bottom row of the stitch number display to “1”.

4

(Display turns off)

(5 seconds or more)

1. Then, press and hold the end backtack key (1) for 5 seconds or more. (The display will turn off.)

2. After this, “Ar” will flash and the initialization will be complete.

5

Set DIP switch -3 to ON. (The settings will be locked.)

3143M

0706B

Control box

0707B

3150M

S-7200B

5. ADJUSTING THE ROTARY HOOK LUBRICATION AMOUNT (-[]0[], []3[] specifications)

23

5. ADJUSTING THE ROTARY HOOK LUBRICATION AMOUNT (-[]0[], []3[] specifications)

CAUTION

Be careful not to touch your fingers or the lubrication amount check sheet against moving parts such as the rotary hook or the feed mechanism when checking the amount of oil supplied to the rotary hook, otherwise injury may result.

Use the following procedure to check the amount of oil being supplied to the rotary hook when replacing the rotary hook or when changing the sewing speed.

NOTE:

If the sewing machine is sub-class -[]5[], it is a fully dry-type machine and so adjustment of the rotary hook lubrication amount is not necessary.

1. Remove the thread from all points from the thread take-up to the needle.

2. Use the lifting lever to lift the presser foot.

3. Run the machine at the normal sewing speed for approximately 1 minute without sewing any material (following the same start/stop pattern as when actually sewing).

4. Place the lubrication amount check sheet (1) underneath the rotary hook (2) and hold it there. Then run the sewing machine at the normal sewing speed for 8 seconds. (Any type of paper can be used as the lubrication amount check sheet (1).)

5. Check the amount of oil which has spattered onto the sheet.

If adjustment is necessary, carry out the following operations in “Adjusting the lubrication amount”.

NOTE:

If the lubrication amount does not match the correct amount shown in the illustration at left (if the amount of spattered oil is too much or none at all), turn the adjusting screw (3) clockwise to fully tighten it, turn it back counterclockwise by 2 1/2 turns, and then carry out the following adjustment.

1. Tilt back the machine head.

2. Turn the adjusting screw (3) to adjust the lubrication amount.

・ If the rotary hook adjusting screw (3) is turned

clockwise, the lubrication amount becomes greater.

・ If the rotary hook adjusting screw (3) is turned

counterclockwise, the lubrication amount becomes smaller.

3. Check the lubrication amount again according to the procedure given in “Checking the lubrication amount” above.

* Turn the adjusting screw (3) and check the lubrication

amount repeatedly until the lubrication amount is correct.

4. Check the lubrication amount again after the sewing machine has been used for approximately two hours.

Less oil More oil

3686M

2303M

Approx. 25mm

Approx. 70mm

Too little

Spattered oil

Too much Correct

2304M

Bed

5–10mm

0935M

S-7200B

6. ADJUSTMENTS

24

6. ADJUSTMENTS

CAUTION

Maintenance and inspection of the sewing machine should only be carried out by a qualified technician.

Ask your Brother dealer or a qualified electrician to carry out any maintenance and inspection of the electrical system.

If any safety devices have been removed, be absolutely sure to re-install them to their original positions and check that they operate correctly before using the machine.

Use both hands to 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

If the power switch needs to be left on when carrying out some adjustment, be extremely careful to observe all safety precautions.

6-1. Adjusting the actuator position

The installation position for the actuator (1) can be adjusted to <A> or . Adjust so that it is in a position where it is easy to operate.

1. Remove the two screws (2).

2. Move the switch setting base (3) to move the actuator (1)

to the preferred position <A> or .

3. Tighten the two screws (2).

3687M

3688M

Back

S-7200B

6. ADJUSTMENTS

25

6-2. Adjusting the safety switch position

The safety switch (1) is normally installed as shown in figure [A]. However, if the processing method used for the table leaves too much space between the machine head and the table hole, it may adversely affect the operation of the safety switch (1).

The standard amount of clearance between the machine head and the table hole is 1.5 mm. If the clearance is 3.5 mm or more, install the safety switch (1) so that the washer (2) is on the machine head side as shown in Figure [B].

* If the position cannot be satisfactorily adjusted in this way,

add more washers of the same thickness.

3689M

3690M

3691M

3692M

Sewing machine

Table

By changing the position of the safety switch, the required spring stroke can be maintained.

Clearance is too large.

If the spring stroke is too small, the safety switch will not operate.

Reduce the clearance.

3.5 mm or more

S-7200B

6. ADJUSTMENTS

26

6-3. Adjusting the thread take-up spring

The standard position of the thread take-up spring (1) is 6-8 mm [4-6 mm for -[][]5 specifications] above the surface of the thread guide (3) when the presser foot (2) is lowered.

1. Lower the presser foot (2).

2. Loosen the set screw (4).

3. Turn the thread tension bracket (5) to adjust the spring

position.

4. Securely tighten the set screw (4).

The standard tension of the thread take-up spring (1) varies in accordance with the machine specifications as shown in the table.

-[][]S specifications 0.1 - 0.24N

-[][]3 specifications 0.25 - 0.35N

-[][]5 specifications 0.30 - 0.5N

1. Push the needle thread with your finger until it is slightly higher than the thread tension bracket (5) and so that the upper thread is not pulled out.

2. Pull the upper thread down until the thread take-up spring (1) is at the same height as the base of the thread guide (3), and then measure the tension of the thread take-up spring (1).

3. Insert a screwdriver into the slot of the tension stud (6), and turn the screwdriver to adjust the tension of the thread take-up spring (1).

NOTE: If using the tension gauge (7) (sold separately) to

measure the tension, take the reading from the scale on the side of the red line.

2274M 3693M

3694M

<-[][]S>

0.1 - 0.24N

<-[][]3>

0.25 - 0.35N

<-[][]5>

0.3 - 0.5N

Scale

<-[][]S / [][]3>

6-8mm

<-[][]5>

4-6mm

S-7200B

6. ADJUSTMENTS

27

6-4. Adjusting arm thread guide R

The standard position of arm thread guide R (1) is the position where the screw (2) is in the center of the adjustable range for arm thread guide R (1).

* To adjust the position, loosen the screw (2) and then

move arm thread guide R (1).

・ When sewing thick material, move arm thread guide R

(1) to the left. (The thread take-up amount will become greater.)

・ When sewing thin material, move arm thread guide R

(1) to the right. (The thread take-up amount will become less.)

6-5. Adjusting the presser foot height

The standard height of the presser foot (1) is 6 mm when the presser foot (1) is raised by means of the lifting lever (2).

1. Loosen the nut (3) of the adjustment screw (4), and then

turn the adjustment screw (4) so that there is no pressure applied to the presser foot.

2. Raise the lifting lever (2). The presser foot (1) will also rise.

3. Remove the oil cap (5).

4. Loosen the bolt (6) and then move the presser bar (7) up or down until the presser foot (1) is at the standard height of 6 mm.

5. Tighten the bolt (6).

6. Replace the oil cap (5).

7. Adjust the presser foot pressure using the adjustment screw (4), and then tighten the nut (3).

3695M

2278M

Becomes less Becomes greater

S-7200B

6. ADJUSTMENTS

28

6-6. Adjusting of the feed dog height

The standard height of the feed dog (1) when it is at its maximum height above the top of the needle plate is 0.8 mm for -[][]S / [][]3 specifications, and 1.2 mm for -[][]5 specifications.

1. Turn the pulley until the feed dog (1) rises to the highest

position.

2. Tilt back the machine head.

3. Loosen the screw (2).

4. Turn the feed lifting rock bracket stud (3) within a range of 90° from the reference line (4) to adjust the vertical height of the feed bar (5). (Fig. [A])

5. Tighten the screw (2).

* If you are worried about the angle of the feed dog (1), turn

the shaft (6) while carrying out the above adjustment. (Fig. [B]) (Refer to “6-7. Adjusting the feed dog angle” on the next page for details of this operation.)

2279M

<-[][]S / [][]3>

0.8mm

<-[][]5>

1.2mm

Becomes higher

Becomes lower

3696M

Standard

Becomes lower

Becomes higher

2281M

2282M

Standard

Becomes lower

Becomes higher

Standard

Becomes lower

Becomes higher

Needle plate

S-7200B

6. ADJUSTMENTS

29

6-7. Adjusting the feed dog angle

The standard angle for the feed dog (1) when it is at its highest position above the needle plate is when the “

” mark (or V groove) on the shaft (2) is aligned with the feed rocker bracket arm (3) and the feed dog (1) is parallel to the needle plate.

1. Turn the machine pulley to move the feed dog (1) to its

highest position above the needle plate.

2. Tilt back the machine head.

3. Loosen the two set screws (4).

4. Turn the shaft (2) in the direction of the arrow within a

range of 90° with respect to the standard position. (Fig. [C])

・ In order to prevent puckering, lower the front of the

feed dog (1).

・ In order to prevent the material from slipping, raise the

front of the feed dog (1).

5. Securely tighten the two set screws (4).

* If you would like to tilt the feed dog (1) further, turn the

feed lifting rock bracket stud (5) while carrying out the above adjustment. (Fig. [D]) (Refer to “6-6. Adjusting the feed dog height” on the previous page for details of this operation.)

* The height of the feed dog (1) will change after the angle

has been adjusted, so it will be necessary to re-adjust the height of the feed dog (1).

3697M

Lower the front

Raise the front

2284M

Standard

Lower the front

Raise the front

Parallel

Needle plate

2285M

Standard

Lower the front

Raise the front

Standard

Back is raised

Back is lowered

S-7200B

6. ADJUSTMENTS

30

6-8. Adjusting the needle bar height

Reference line (a), which is the second line from the bottom of the needle bar (1)(fourth line from the bottom when using a DA x 1 needle) should be aligned with the lower edge of the needle bar bush D (2) as shown in the illustration when the needle bar (1) is at its lowest position.

1. Turn the machine pulley to set the needle bar (1) to its

lowest position.

2. Remove the oil cap (3).

3. Loosen the screw (4) and then move the needle bar (1) up

or down to adjust its position.

4. Securely tighten the screw (4).

5. Replace the oil cap (3).

6-9. Adjusting the needle and feed mechanism timing

The standard position for point of the needle is as described below when the feed dog (1) is lowered from its highest position until it is aligned with the top of the needle plate (2). (At this time, the “-” mark on the lower shaft will be aligned with the center of the scale (4) (“O” mark) on the vertical cam (3).)

<-[][]S / [][]3>

The top of the feed dog (1) and the top of the needle plate (2) should be aligned, and the point of the needle should be approximately 1 mm below the needle plate (2).

<-[][]5>

The top of the feed dog (1) and the top of the needle plate (2) should be aligned, and there should be a clearance of approximately 3 mm between the point of the needle and the needle plate (2).

1. Tilt back the machine head.

2. Loosen the two set screws (5), and then turn the vertical

cam (3) sligtly to adjust the timing. (Use the “-” mark on the lower shaft and the alignment position on the scale (4) of the vertical cam (3) as a guide.)

・ To set to the standard position, align the “-” mark on

the lower shaft with the center of the scale (4) (“O” mark) on the vertical cam (3). ([A] in the illustration)

・ To prevent material slippage from occurring, retard the

needle timing. (Turn the vertical cam (3) in the direction of (B). Refer to [B] in the illustration.)

・ To improve thread tightening, advance the needle

timing. (Turn the vertical cam (3) in the direction of (C). Refer to [C] in the illustration.)

NOTE: Do not turn the vertical cam (3) too far in the

direction of (C), otherwise it could cause the needle to break.

3. After adjustment is completed, securely tighten the two

screws (5).

2286M

3698M

2288M

<-[][]S / [][]3> <-[][]5>

Approx. 1mm

Approx. 3mm

3699M

(Standard)

Needle timing is advanced

Needle timing is retarded

S-7200B

6. ADJUSTMENTS

31

6-10. Adjusting the needle and rotary hook timing

The tip of the rotary hook (3) should be aligned with the center of the needle (4) when the needle bar (1) moves up from its lowest position to the position where reference line (b), which is the line at the bottom of the needle bar (1)(third line from the bottom when using a DA x 1 needle), is aligned with the lower edge of the needle bar bush D (2) as shown in the illustration.

(At this time, the gap between the upper edge of the needle hole and the rotary hook tip (3) will be 0.5 - 0.7 mm.)

1. Turn the machine pulley to raise the needle bar (1) from

its lowest position until reference line (b) is aligned with the lower edge of the needle bar bush D (2) as shown in the illustration. (The needle should rise by 1.8 mm [2.2 mm for -[][]5 specifications] and the distance from the needle hole to the tip of the rotary hook should be 0.5 - 0.7 mm.)

2. Loosen the three set screws (5), and then align the tip of

the rotary hook (3) with the center of the needle (4). The distance between the tip of the rotary hook (3) and the needle (4) should be approximately 0 - 0.05 mm.

3. Securely tighten the three set screws (5).

Check that the clearance between the rotary hook (6) and the bobbin case holder position bracket (7) is enough to allow the thread being used to pass through smoothly. The clearance should be 0.4 - 0.7 mm for -[][]S / [][]3 models, and 0.6 - 1.1 mm for -[][]5 models.

2291M

0.5 - 0.7mm

0.05mm

2290M

0 - 0.05mm

2292M

2293M 3700M

<-[][]S / [][]3> 0.4 - 0.7mm <-[][]5> 0.6 - 1.1mm

1.8mm

<-[][]S / [][]3>

2.2mm

<-[][]5>

S-7200B

6. ADJUSTMENTS

32

Lowest position of needle ba

r

Raised 5 mm

6-11. Adjusting the thread trimming timing

Remove the presser foot, needle plate and feed dog.

< Thread trimming cam position adjustment >

1. Turn the machine pulley to raise the needle bar 5 mm

from its lowest position (reference line (a) position) so that reference line (b) is aligned with the bottom edge of the needle bar bush.

2. At the above position, push the plunger (1) of the thread

trimming solenoid with your finger in the direction of the arrow. Adjust the position of the thread trimmer cam (2) at this time so that the roller shaft (4) of the thread trimmer cam lever assembly (3) touches the hollow (c) of the thread trimmer cam (2) and so that the clearance between the edge of the thread trimmer cam (2) and the roller shaft (4) is 0.6 to 0.8 mm, and then tighten the set screws (5). (Fig. [A])

3. Check that the clearance between the edge of the thread

trimmer cam (2) and the roller shaft (4) is 0.5 mm when the roller shaft (4) returns to the right. (Fig. [B])

* Tighten the two set screws (5) to approximately 4 N.m.

1. Turn the machine pulley, and then push the plunger (1) of

the thread trimming solenoid with your finger.

2. In this condition, turn the machine pulley until the roller

shaft (4) of the thread trimmer cam lever assembly (3) is sitting on top of the thread trimmer cam (2), then move the thread trimmer lever (7) to adjust its position so that the tip of the fixed knife (5) and the blade of the movable knife (6) are meshed by 1 mm, and then tighten the screw (8).

* Adjust so that the meshing amount is 1 mm at this time,

by using the position where the mating marks on the thread trimmer holder and the bushing are aligned as a guide.

* Tighten the screw (8) so that there is no play in the

forked shaft (9).

* The lower thread finger (10) must be underneath the

movable knife (6).

3. Install the feed dog, needle plate and presser foot.

Reference line (b)

Reference line (a)

Direction of cam rotation

Mating mark

1204B

1205B

1206B

1207B

1208B

S-7200B

6. ADJUSTMENTS

33

6-12. Adjusting the thread take-up amount (-[][]3 specifications)

CAUTION

Turn off the power switch before carrying out this operation. The machine may operate if the treadle is depressed by mistake, which could result in injury.

NOTE:

Do not use this function with models that are not -[][]3 specifications.

If the thread take-up amount is small and the thread breaks easily when sewing heavy materials, you can increase the thread take-up amount.

1. Remove the face plate.

2. Remove the two rubber caps (1).

3. Use a hexagonal wrench 3 to loosen the set screws (2)

and (3) by approximately two turns.

4. Adjust the thread take-up amount.

Turn the thread take-up support shaft (4) clockwise so that the groove (5) is facing straight upward.

Turn the thread take-up support shaft (4) counterclockwise so that the groove (5) is facing straight downward.

5. With the thread take-up support shaft (4) pushed in as far

as it will go, first tighten the set screw (2) until it touches the screw stop on the thread take-up support shaft (4).

6. After this, tighten the set screw (3).

7. Install the two rubber caps (1).

8. Install the face plate.

Increases

Standard

Screw

stop

3677M

S-7200B

6. ADJUSTMENTS

34

6-13.

Adjusting the needle up stop position (When using the operation panel)

1. While pressing the needle up/down key (1), turn on the power switch.

2. “n.0 xx” will appear in green in the main display (2). (“xx” is the setting value for the needle up stop position, and “0” is the default setting.)

3. Press the or key (3) to change the setting value for the needle up stop position.

• If you press the key, the setting value will increase

up to 20 and the needle up stop position will become lower.

• If you press the key, the setting value will decrease

down to -10 and the needle up stop position will become higher.

4. Press the ENTER key (4) for two seconds or more. A long buzzer will sound and the main display (2) will change to stitch number display mode. (This completes the needle up stop position setting.)

* A setting value of “10” corresponds to an angle of rotation

of approximately 10° for the upper shaft.

* If DIP switch 3 is not set to OFF, this adjustment cannot be

carried out.

2210M

3657M

2138M 2139M

(–10 – 20)

Becomes higher

Becomes lower

S-7200B

6. ADJUSTMENTS

35

Display A b c d E F

Value 10 11 12 13 14 15

6-14. Setting the needle up stop position and needle down stop position

(

If using the control box panel)

Meaning of displays during setting

• The stop position is set numerically, and “A” to “F” represent the numbers “10” to “15” respectively.

• A setting value of “8” corresponds to an angle of rotation of approximately 8° for the upper shaft.

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

1

Set DIP switch -3 to OFF.

(This will cancel the lock so that the functions can be set.)

2

While pressing the end backtack key (1), press the power switch (2) to turn on the power.

3143M

0706B

Control box

S-7200B

6. ADJUSTMENTS

36

1

(Example: -8)

1. Press the start backtack key (3) so that “

¯

” is displayed

in the top row of the stitch number display.

2. Press the end backtack key (1) to set the value.

2

Set DIP switch -3 to ON. (The settings will be locked.)

1

(Example: 3)

1. Press the start backtack key (3) so that “-” is displayed in the top row of the stitch number display.

2. Press the end backtack key (1) to set the value.

2

Set DIP switch -3 to ON. (The settings will be locked.)

Becomes higher

Becomes lower

Becomes higher

Becomes lower

0704B

Becomes lower

Becomes higher

3657M

0705B

S-7200B

6. ADJUSTMENTS

37

6-15. Adjusting the treadle

If the machine starts running at low speed when your foot is simply resting on the treadle, or if the treadle pressure is felt to be too weak, adjust the position (a to c) at which the treadle spring (1) is hooked onto the treadle lever (2).

* a is the weakest position, and it becomes gradually

stronger at b and c respectively.

1. Loosen the nut (3) and turn the bolt (4).

* When the bolt (4) is tightened, the treadle operation

becomes heavier, and when it is loosened, the operation becomes lighter.

2. Tighten the nut (3).

Remove the nut (5), and then move the connecting rod joint (6) from the position in figure A to the position in figure B. The treadle stroke will then be increased by approximately 27 %. At this time, the treadle forward and backward depression sensitivity will change, so readjust if necessary.

6-16. Adjusting the presser foot floating amount (minute lifting amount)

When sewing stretch materials and materials with long pile, you can make minute adjustments to the floating amount for the presser foot (1) in accordance with the material.

1. Turn the sewing machine pulley by hand to move the feed dog (2) below the needle plate (3).

2. Use the lifting lever to lower the presser foot (1).

3. Loosen the nut (4).

4. Use a hexagon wrench to turn the adjusting screw (5) to adjust the floating amount.

・ To raise the presser foot (1) ...

Turn the adjusting screw (5) clockwise.

・ To lower the presser foot (1) ...

Turn the adjusting screw (5) counterclockwise.

5. Tighten the nut (4).

* After making the adjustment, sew a piece of material to

check the floating amount.

2301M

2307M

Floating amount

Raise

Lower

3701M

2302M

S-7200B

7. REPLACING PARTS

38

7. REPLACING PARTS

CAUTION

Replacement of parts should only be carried out by a qualified technician.

Use only the proper replacement parts as specified by Brother.

Turn off the power switch and disconnect the power cord before replacing any parts. The machine may operate if the treadle is depressed by mistake, which could result in injury.

Use both hands to 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.

Be sure to wear protective goggles and gloves when handling the lubricating oil and grease, so that they do not get into your eyes or onto your skin, otherwise inflammation can result. Furthermore, do not drink the oil or eat the grease under any circumstances, as they can cause vomiting and diarrhea. Keep the oil out of the reach of children.

7-1. Fixed knife

1. Tilt back the machine head.

2. Remove the screw (1), and then remove the rotary hook

stopper (2).

3. Remove the screw (3), and then remove the fixed knife

(4).

* Carry out the above steps in reverse to install the fixed

knife (4).

Sharpening the fixed knife

If the cutting performance deteriorates, sharpen the fixed knife (4) on a whetstone (5) as shown in the illustration.

7-2. Movable knife

1. Remove the needle.

2. Lift up the presser foot using the lifting lever.

3. Remove the two screws (1), and then remove the needle

plate (2).

4. Turn the machine pulley to raise the needle bar to its

highest position.

5. Tilt back the machine head.

6. Push the thread trimmer connecting rod (3) in the

direction of the arrow until the two screws (4) can be seen.

7. Remove the two screws (4), and then remove the

movable knife (5).

* Carry out the above steps in reverse to install the

movable knife (5).

2311M

2309M

2310M

0739B

S-7200B

7. REPLACING PARTS

39

7-3. Motor and timing belt

< Timing belt removal >

1. Remove the side plate (1).

2. Remove the three screws (2), and then remove the motor cover (3).

3. Tilt back the machine head.

4. While pushing the timing belt (4) in the direction of the arrow, turn the machine pulley (5) forward to remove the timing belt (4) from timing pulley D (6).

5. Return the machine head to its original position.

6. Turn the machine pulley (5) until the four set screws (8) on the joint (7) are facing toward the front. Loosen the two set screws (8) at the left by about five turns each.

7. Remove the three screws (9), and then remove the machine pulley (5).

8. Remove the three screws (10), and then remove the motor (11).

* If it is difficult to remove the motor (11), tighten one of

the removed screws (10) into the screw hole (a) at the left or right. The motor (11) can then be pulled forward and removed. (Fig. [A])

9. Pull out the timing belt (4) by hand while being careful not to get it caught on the fan (12).

< Motor removal >

Carry out steps 1 and 2 and steps 6 to 8 of <Timing belt removal>.

1209B

1210B

1211B

S-7200B

7. REPLACING PARTS

40

< Timing belt installation >

1. Place the timing belt (4) onto timing pulley U (13).

2. Secure the motor (11) with the three screws (10).

* Insert the motor (11) so that the upper set screws (8)

on the joint (7) are facing toward the front and also so that the notch (b) on the motor shaft (14) is facing toward the front.

3. Tighten the two set screws (8) at the left side of the joint (7) starting from the one at the top.

* Check that the notch (c) on the motor is in the position

shown in the illustration and that the upper set screws (8) on the joint (7) is facing toward the front at this time.

4. Secure the motor cover (3) with the three screws (2).

5. Raise the thread take-up to its highest position, turn the machine pulley (5) so that the reference line (d) is aligned with the mark (e) on the motor cover (3) as shown in the illustration, and then secure the machine pulley (5) by tightening the three screws (9).

* Tighten the three screws (9) so that they are in the

middle of the screw holes. (The reference line (d) and the mark (e) may move out of alignment when tightening the screws, but this is not a problem.)

6. Adjust the positions of the machine pulley (5) and timing pulley D (6) as follows.

1) Tilt back the machine head.

2) Turn timing pulley D (6) forward to lower the feed dog (15) until it is at the same height as the needle plate (16).

3) Turn the machine pulley (5) forward to adjust so that the tip of the needle is at the following position.

<-[][]S・[][]3> So that the point of the needle is

approximately 1 mm below the needle plate (16)

<-[][]5> So that there is a clearance of approximately 3

mm between the point of the needle and the top of the needle plate (16)

7. Place the timing belt (4) onto timing pulley D (6). * Check that the timing belt (4) is placed on the back

position of the tension pulley (17).

8. Turn the machine pulley (5) forward until the timing belt (4)

is set securely.

9. Return the machine head to its original position.

10. Install the side plate (1).

* After the timing belt has been installed, be sure to

then carry out the steps in <Timing belt installation check> (refer to the next page).

< Motor installation >

Carry out steps 2 to 5 and step 10 of <Timing belt installation>.

1213B 1214B

<-[][]S・[][]3> <-[][]5>

Approx. 1mm

Approx. 3mm

1212B

S-7200B

7. REPLACING PARTS

41

< Timing belt installation check >

1. Check that the needle and rotary hook timing is correct.

(Refer to “6-10. Adjusting the needle and rotary hook timing”.)

* If they are correct, continue from step 5, otherwise

continue from step 2.

2. Check that the needle and feed mechanism timing is

correct. Turn the machine pulley (5) forward to lower the feed dog (15) from its highest position until it is aligned with the top of the needle plate (16), and check that the tip of the needle is at the following position at this time.

The top of the feed dog (15) and the top of the needle plate (16) should be aligned, and the point of the needle should be approximately 1 mm below the needle plate (16).

The top of the feed dog (15) and the top of the needle plate (16) should be aligned, and there should be a clearance of approximately 3 mm between the point of the needle and the needle plate (16).

* If it is not in the correct position, carry out the following

steps.

1) Tilt back the machine head, and then loosen the two set screws (18).

2) Turn timing pulley D (6) forward to lower the feed dog

(15) until it is at the same height as the needle plate (16).

3) While holding the vertical cam (19) with one hand so that

it will not move, turn the machine pulley (5) forward to lower the needle to the correct position.

4) Tighten the two set screws (18).

3. Adjust the needle and rotary hook timing so that it is correct. (Refer to “6-10. Adjusting the needle and rotary hook timing”.)

4. Check that the thread trimming timing is correct. If it is not correct, adjust it by following the adjustment procedure. (Refer to “6-11. Adjusting the thread trimming timing”.)

5. Set the sewing machine to needle up stopping, and then operate the sewing machine and let it stop. Check that the reference line (d) on the machine pulley (5) is within the range of the mark (e) on the motor cover (3) at this time.

1215B

1216B

1213B

<-[][]S・[][]3> <-[][]5>

Approx. 1mm

Approx 3mm

<-[][]S・[][]3>

<-[][]5>

S-7200B

7. REPLACING PARTS

42

7-4. Rotary hook RP

If replacing the standard rotary hook with a rotary hook RP (lubrication-free rotary hook) on sub-class -40[] or -43[] machines, use the following parts.

S52936-001 (ROTARY HOOK, W/BOX)

S35786-001 (SCREW, CAP)

NOTE: When using the rotary hook RP (lubrication-free rotary hook), set the sewing speed to 4,000 rpm or less.

1. Remove the needle and the presser foot.

2. Remove the needle plate (1) and the feed dog (2).

3. Remove the rotary hook.

4. Replace the screw (3). Tighten the screw (3) securely.

5. Install the rotary hook RP(4) and the needle. After installing the rotary hook RP, adjust the needle and rotary hook timing. (Refer to page 31.)

6. Install the feed dog (2).

7. Install the needle plate (1). Adjust the installation position of the feed dog (2) so that it is in the middle of the needle plate (1) groove.

8. Install the presser foot.

Tighten the adjusting screw (5) as far as it will go, and then turn it back the other way about three full turns. (At this time, the head (A) of the adjusting screw (5) should be almost flush with the edge (B) of the bed.)

NOTE: If the sewing machine is used while the adjusting

screw (5) is in the fully-tightened position, it will cause oil to leak out through the gap between the rotary hook shaft (6)and the bracket (7).

2313M

0741B

0740B

S-7200B

7. REPLACING PARTS

43

7-5. Feed bar shaft, Lifting feed shaft

When changing over these parts, apply grease as described below and then install the parts to the sewing machine.

* Use Brother-specified grease (SA7300-001).

1. Apply grease to the holes of each part as shown in the

arrow until a small amount of grease overflows.

2. Tighten the screws to force the grease in.

3. Wipe away any excess grease from around the screws.

4. Apply grease to the meshing areas (

areas) of each

part.

5. Install each part to the sewing machine.

Feed bar shaft unit

Grease

2317M

Grease

0742B

Grease

Be particularly sure to apply grease to the groove

Lifting feed shaft unit

2316M

2319M

S-7200B

8. APPLYING GREASE (-[]3[], []5[] specifications)

44

8. APPLYING GREASE (-[]3[], []5[] specifications)

8-1. When using the operation panel

If “GrEASEUP” flashes on the main display (1) and a buzzer sounds when the power switch is turned on, it means that grease needs to be applied. (The sewing machine will not operate at this time, even if the treadle is depressed.) Apply grease as required, while referring to the following for details.

1. Press the RESET key (2).

2. The main display (1) will change to stitch number display mode, and sewing will be possible when the treadle is depressed. (The power indicator (3) will keep flashing.)

NOTE:

・ If you do not apply grease when the “GrEASEUP” notification appears, the notification will continue to appear and the

power indicator (3) will flash each time the power is turned on until you reset the notification by carrying out the procedure on the following page.

・ If you continue to use the sewing machine after the “GrEASEUP” notification appears without applying grease (or

without carrying out the reset procedure), “Err100” will appear after a certain period of time and the sewing machine will be forcibly prevented from operating for safety reasons. If this happens, apply grease and carry out the reset procedure.

* If you continue to use the sewing machine after carrying out the reset procedure but without applying grease,

problems with the sewing machine may result.

Use Brother-specified <GREASE (SA7300-001)>.

Using the tube

3682M

2191M

S-7200B

8. APPLYING GREASE (-[]3[], []5[] specifications)

45

1. Turn the power switch to “OFF”.

2. Remove the screws and the set screws.

3. Apply grease to each of the holes until the grease overflows slightly.

4. Tighten the screws and the set screws in order to push the grease in.

5. Turn the machine pulley by hand to move the needle bar up and down several times in order to disperse the grease.

6. Use a cloth to wipe away any excess grease from around the screws and set screws and from underneath needle bar bush D.

7. Carry out the reset procedure given below.

After the grease has been applied, carry out the following procedure to reset the grease consumption amount.

1. Turn the power switch to “ON”. “GrEASEUP” will flash in the main display (1) and the buzzer will sound.

2. Press the RESET key (2). The main display (1) will change to stitch number display mode.

3. Press and hold the LOCK key (4) for 2 seconds or more. The lock icon (5) will switch off and the lock will be released.

4. Press the FUNC (Function) key (6). “n.134 Pxxx” will appear in green in the main display (1). (“Pxxx” indicates the grease consumption amount. For example, “P100” means that 100% of the grease has been consumed.)

5. Press the rightmost key (7). The “Pxxx” will change to “P 0”.

6. Press and hold the ENTER key (8) for two seconds or more. The buzzer will make a long beep, and then the main display (1) will change to stitch number display mode.

7. Depress the treadle to run the sewing machine for 1 second or more.

8. Turn the power switch to “OFF”. (This completes the reset procedure.)

<-[]5[] specifications>

Marked red

3685M

2139M

3683M

3684M

Turn the machine pulley to lower the needle bar until the hole is visible.

<-[]3[], []5[] specifications>

S-7200B

8. APPLYING GREASE (-[]3[], []5[] specifications)

46

8-2. When using the control box panel

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

If “GU” flashes in the stitch number display (1) on the control box panel when the power switch is turned on, it indicates that it is time for grease to be applied.

(The sewing machine will not operate at this time, even if the treadle is depressed.)

Apply grease as required, while referring to the following for details.

1. Press the start backtack key (3).

2. The “GU” in the stitch number display (1) will stop flashing and disappear, and sewing will be possible when the treadle is depressed. (The power indicator (2) will flash.)

NOTE:

・ “GU” will appear each time the power is turned on until you apply grease and reset the notification by carrying out the

reset procedure on the following page.

・ If you continue to use the sewing machine after the “GU” notification appears without applying grease (or without

carrying out the reset procedure), “-0” will appear in the stitch number display (1) after a certain period of time and the sewing machine will be forcibly prevented from operating for safety reasons. If this happens, apply grease and carry out the reset procedure.

* If you continue to use the sewing machine after carrying out the reset procedure but without applying grease,

problems with the sewing machine may result.

Use Brother-specified <GREASE (SA7300-001)>.

Using the tube

3682M

3704M

S-7200B

8. APPLYING GREASE (-[]3[], []5[] specifications)

47

1. Turn the power switch to “OFF”.

2. Remove the screws and the set screws.

3. Apply grease to each of the holes until the grease overflows slightly.

4. Tighten the screws and the set screws in order to push the grease in.

5. Turn the machine pulley by hand to move the needle bar up and down several times in order to disperse the grease.

6. Use a cloth to wipe away any excess grease from around the screws and set screws and from underneath needle bar bush D.

7. Carry out the reset procedure given below.

After the grease has been applied, carry out the following procedure to reset the grease consumption amount.

1. Set DIP switch -3 inside the control box to OFF. (This will cancel the lock so that the functions can be set.)

2. While pressing the end backtack key (4), press the power switch to turn on the power.

3. Press the start backtack key (3) so that “G” is displayed in the top row of the stitch number display.

4. Press the end backtack key (4) to set the value in the bottom row of the stitch number display to “1”.

5. Then, press and hold the end backtack key (4) for 5 seconds or more. (The display will turn off.)

6. After this, “Gr” will flash and the reset operation will be complete.

7. After the reset operation is complete, set DIP switch -3 to ON. (The settings will be locked.)

2139M

3685M

<-[]3[]・[]5[] specifications > <-[]5[]specifications >

3683M

3684M

Marked red

Turn the machine pulley to lower the needle bar until the hole is visible.

S-7200B

9. CONTROL SYSTEM

48

9. CONTROL SYSTEM

Turn on the power switch (1).

A. When the treadle is depressed

1. When the treadle (2) is depressed, a voltage corresponding to the amount of treadle depression is transmitted by the treadle unit (3) to the control box (4).

2. The DD motor (5) that is directly linked to the sewing machine receives a voltage that corresponds to the treadle depression amount from the control box (4), causing the DD motor (5) to operate at the speed represented by the treadle depression amount, and this makes the sewing machine operate.

B. When the treadle is returned to the neutral position

1. When the treadle (2) is returned to the neutral position (when the operator's foot is removed from the treadle), a signal indicating that the treadle is at the neutral position is transmitted by the treadle unit (3) to the control box (4), and the electrical brake is then applied to slow the DD motor (5).

2. The encoder circuit board that is installed to the DD motor (5) sends a signal to the control box (4) so that the electrical brake is applied in order to stop the sewing machine at the stopping position (needle up or needle down) set by the pulley (6) that is attached to the DD motor (5).

C. When the treadle is depressed backward

1. When the treadle (2) is depressed backward, a signal indicating thread trimmer operation is transmitted by the treadle unit (3) to the control box (4), and the DD motor (5) slows down to the thread trimming speed (inching speed).

2. The encoder circuit board that is installed to the DD motor (5) sends a signal to the control box (4) so that the electrical brake is applied in order to stop the sewing machine at the needle up stopping position set by the pulley (6) that is attached to the DD motor (5). The thread trimming operation is carried out immediately before the sewing machine stops at the needle up stop position.

2320M

S-7200B

10. CONTROL BOX AND MOTOR

49

10. CONTROL BOX AND MOTOR

10-1. Removing and installing the control box

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

1. Remove the cable tie (1) and the shielded wire clips (2) and (3) in that order, and then disconnect all of the connectors (4) to (7) from the sewing machine.

* Be careful not to break the pawls of connectors (5), (6)

and (7).

2. Disconnect the power supply connector (8) and the motor

connector (9).

3. Disconnect the ground wire (10).

4. Loosen the nuts (11) and (12) (without removing them).

5. Remove the bolt (13) and nut (14).

6. Pivot the control box around the bolt (15) and pull it out to remove it from the table.

Install by following the removal procedure in reverse.

2324M

0656B

2322M

2323M

S-7200B

10. CONTROL BOX AND MOTOR

50

10-2. Control box and motor rating plate

・ Check the phase, voltage and type for the control box. ・ Some specifications are identical for both single- and three-phase. (appears on name plate)

Model

MD-7410: Single-phase MD-7510: Three-phase

Serial No.

144-52

1

Japan

2

Asia/Middle East

3

USA/Mexico

4

Canada

5

Oceania (C-TICK)

7

Turkey/ North Africa

9

China

Destination

L

Europe/Greece (CE)

1

100V

2

110V

3

200V

5

220–240V

Power supply voltage

8

380–415V

4

1 forward 1 backward step type

Treadle unit

6

2 forward 2 backward step type

Operation panel

4

External

Sewing machine

1

S-7200A

Phase

Voltage

Serial No.

2325M

S-7200B

10. CONTROL BOX AND MOTOR

51

<Motor>

Serial No.

2326M

2327M

S-7200B

10. CONTROL BOX AND MOTOR

52

10-3. Control circuit board

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

CN18 Head detector unit connector CN12 Solenoid-type presser lifter connector CN13 Sewing machine connector

CN4 Synchronizer connector CN5 Operation panel connector

Connect to sewing machine connectors.

CN7 Relay connector CN8 Coupler connector

Connect to power supply circuit board connectors.

CN1 Control power supply connector Connect to transformer connectors. CN2 Treadle connector Connect to treadle unit connector.

CN3 Standing operation connector Connect to plug (sold separately) for standing operation CN15 Puller connector Connect to solenoid for puller or other device. CN11 Option connector 1 Connect to sewing speed actuator.

CN6 Option connector 2 For input/output signals used by external devices

CN9 Option connector 3 Connect to stitch counter actuator. CN10 Cooling fan power supply connector Only used for three-phase high-voltage specifications.

Connectors

CN16 Thermistor connector Connect to shorted connector when not using three-phase

high-voltage specifications.

0657B

S-7200B

10. CONTROL BOX AND MOTOR

53

F2 5A Solenoid power supply fuse (5A)

Fuses

F1 5A Illumination lamp power supply fuse (5A)

For preventing overcurrent

DIP switch DSW DSW For function selection

LD2 Red LED Indicates power supply circuit board problems.

LED indicators

LD1 Green LED Indicates that the power is on.

Connector CN6

Signal name Remarks

1 +5V DC +5V

2 IN Variable signal input For stitch counting

3 SPSP Speed command input [Not used by the S-7200A]

4 STOP Operation prevention input L level: Operation prevented

5 ND Needle down signal output (*) L level: Needle down stop position

6 NU Needle up signal output (*) L level: Needle up stop position

7 ENG Machine shaft sync signal (*) 45 pulses/stitch

8 STBY Operation signal output (*) H level: Operation in progress

9 S0V 0V (GND)

10 ENC-A A phase signal output (*) Encoder A phase (180 pulses/stitch)

11 ENC-B B phase signal output (*) Encoder B phase (180 pulses/stitch)

(*) Open collector output

Connector CN9

Signal name Remarks

1 +5V DC +5V

2 UNTH_LED Stitch counter LED signal output

Stitch counter warning LED

3 UNTH_SW Stitch counter switch input signal

4 S0V 0V (GND)

Stitch counter actuator

5 IN1 Variable input signal 1

6 IN2 Variable input signal 2

Connector CN11

Signal name Remarks

1 +5V DC +5V

2 LED1 Option signal output 1

3 LED2 Option signal output 2

4 LEFT_UP_SW Option signal input 1 Sewing speed actuator (high speed)

5 RIGHT_UP_SW Option signal input 2 Sewing speed actuator (medium speed)

6 RESET_SW Option signal input 3 Sewing speed actuator (low speed)

7 S0V 0V (GND)

S-7200B

10. CONTROL BOX AND MOTOR

54

10-4. Checking the motor and power supply

CAUTION

Turn off the power switch and disconnect the power cord from the wall outlet before carrying out these operations. The machine may operate if the treadle is depressed by mistake, which could result in injury.

If the power switch needs to be left on when carrying out some adjustment, be extremely careful to observe all safety precautions.

<Motor>

1. Disconnect the motor connector 4P (1) from the control box.

2. Measure the resistance of the motor connector (1) using an ohmmeter in the x 1 range. If the value is as shown in the table below, the connector is normal.

Between 2–3 Between 3–4 Between 4–2

Approx. 1.6Ω

1. Disconnect the power supply connector 6P (2) from the control box.

2. Turn on the power switch.

3. Measure the voltage at the power supply connector (2) using the AC voltage range of a multimeter, and check that the voltage is within the allowable range for the specified voltage rating.

100 V type (100–120 V)

Measure the AC voltage between terminals 2–3.

200 V type (200–240 V)

[A] For three-phase

Measure the AC voltage between terminals 4–5, 5–6 and 6–4.

[B] For single-phase

Measure the AC voltage between terminals 4–6.

2329M

1884M

<100 V type>

<200 V type>

Ground wire

Ｕ phase

Ｖ phase

Ｗ phase

1883M

S-7200B

10. CONTROL BOX AND MOTOR

55

10-5. Checking the solenoids

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

1. Disconnect the sewing machine connector 14P (1) from the control circuit board.

2. Measure the resistance of the sewing machine connector (1) using an ohmmeter in the x 1 range. If the values are as shown in the table below, the connector is normal.

Between 3–10 Thread trimming solenoid: Approx.

7.6Ω

Between 4–11 Thread wiper solenoid: Approx. 5.7Ω Between 5–12 Quick reverse solenoid: Approx. 4.8Ω

When actuator is pressed: 0Ω Between 6–13

When actuator is released: ∞ Ω When machine head is upright (switch

ON): 0 Ω

Between 7–14

When machine head is tilted back (switch OFF): ∞ Ω

<Solenoid-type presser lifter connector>

1. Disconnect the solenoid-type presser lifter connector 6P

(2) from the control circuit board.

2. Measure the resistance of the solenoid-type presser lifter

connector (2) using an ohmmeter in the x 1 range. If the values are as shown in the table below, the connector is normal.

Between 3–6 Presser lifter solenoid: Approx. 9.6 Ω

When knee switch is pressed: 0 Ω Between 4–5 When knee switch is released: ∞ Ω

Sewing machine connector 14P

Solenoid-type presser lifter connector 6P

0743B

1886M

Thread trimmer solenoid

Thread wiper solenoid

Quick reverse solenoid

A

ctuator switch

Safety switch

2331M

Knee switch

Presser lifter solenoid

Control box

S-7200B

11. TREADLE UNIT ASSEMBLY

56

11. TREADLE UNIT ASSEMBLY

11-1. Types

・ The two types of treadle unit that are available are the type that controls the automatic presser foot lifter and the type that

does not.

・

You can switch between the two types by <A> changing the hooking position of the spring (1) inside the treadle unit; setting DIP switch 2; and <C> setting the treadle stroke.

Specifications Treadle unit G Treadle unit H Operation Does not control automatic presser lifter Controls automatic presser lifter <A> Difference in spring position

[a]

[b]

DIP switch setting

DIP switch 2: OFF <When depressing the treadle forward> The presser foot lifter control signal is not output when the treadle is being depressed.

DIP switch 2: ON <When depressing the treadle forward> The automatic presser foot lifter signal is output at the position before the treadle depression force suddenly changes.

<C> Signal setting

Carry out the setting in “Setting method for standard depression strokes” on page 58. Set the neutral position, maximum forward position and maximum backward position.

Carry out the setting in “Setting method for standard depression strokes” on page 58. Set the neutral position, maximum forward position and maximum backward position. The first modulation position for the treadle

depression force is set automatically. <D> Depression force

<When depressed forward and depressed backward> The depression force hardly changes at all from the start of depression until full depression.

<When depressed forward and depressed

backward>

The depression force suddenly changes at a point

between the start of depression and full depression.

<E> Depression signal

< When depressed forward > The sewing machine starts. < When depressed backward > The sewing machine starts. (NOTE 1)

<When depressed forward and depressed

backward>

An automatic presser lifter signal is output at the

point before the depression force suddenly

changes, and the sewing machine starts at the point

after the depression force suddenly changes.

(NOTE 1) The presser foot lifter control signal is output while the treadle is depressed backward. However, if DIP switch 1 is

set to OFF, the presser foot lifter control signal is not output when the treadle is depressed backward after the knee switch has been used to raise the presser foot. Furthermore, if Function No. 41 is set to “1”, the presser foot lifter control signal is not output when the treadle is depressed backward.

1840M

1839M

(1)

S-7200B

11. TREADLE UNIT ASSEMBLY

57

11-2. Standard setting values

Specifications Treadle unit G Treadle unit H

Operation

Does not control automatic presser lifter

Controls automatic presser lifter

Spring position setting

No forward/back 1st step modulation (Figure [a] on previous page)

Forward/back 1st step modulation (Figure [b] on previous page)

Function No.

Symbol (diagram

below)

Function

Length from S0 (mm)

Force (N)

Length from S0 (mm)

Force (N)

- S0

Neutral point

0 - 0 -

82 S1

Forward automatic presser lifter operating point

- - 2 (NOTE 1) 10

83 S2

Low speed operation starting point

3 10 5 25

84 S3

Speed change starting point

6 - 7 -

85 S4

Maximum speed reaching point

S5-1 - S5-1 -

- S5

Maximum forward depression point

14.5 12 14.5 32

81 S6

Back automatic presser lifter operating point

- - 2 (NOTE 2) 14

80 S7

Thread trimmer operating point

5 22 5 35

- S8

Maximum back depression point

8 28 8 43

(NOTE 1) Setting is enabled when DIP switch 1 is set to ON and Function No. 13 is set to “1”. (NOTE 2) Setting is enabled when Function No. 12 is set to “0”.

・ When the connecting rod installation position is on the inside, the measurement value is the amount of movement of the

treadle from the neutral position to the forward position and to the backward position.

・ For treadle unit -H, the point of change (F) in the forward depression force is between S1 and S2, and the point of change

(R) in the backward depression force is between S6 and S7.

Speed

Backward depression Neutral Forward depression

1841M

S-7200B

11. TREADLE UNIT ASSEMBLY

58

11-3. Setting method for standard depression strokes

CAUTION

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

・ When the specifications of the treadle unit are changed or if the treadle unit or control circuit board are replaced, it will be

necessary to make new settings according to the procedure described below. Use the following procedure to set the operating positions for the depression stroke.

・ For sewing machines with operation panel, make the settings using the operation panel. (Refer to “A. For the operation

panel”.)

・ For sewing machines without operation panel, make the settings using the control box panel. (Refer to “B. For the control

box panel”.)

A. For the operation panel

1) Signal setting entry

1. Turn off the power switch (1).

2. Set DIP switch No.4 to ON.

3. While pressing the thread trimming key (2), turn on the power switch (1). “PdFF x.xxx” will appear in the main display (3). (x.xxx indicates the depression voltage.)

2) Memorizing the maximum forward position

With the treadle depressed forward to the maximum forward position, press the thread trimming key (2). “Pdnn x.xxx” will appear in the main display (3).

2333M

3192M

2334M

0652B

S-7200B

11. TREADLE UNIT ASSEMBLY

59

3) Memorizing the neutral position

With your foot released from the treadle, press the thread trimming key (2). "Pdrr x.xxx" will appear in the main display (3).

4) Memorizing the maximum backward position

With the treadle depressed backward to the maximum backward position, press the thread trimming key (2). “Pd-- x.xxx” will appear in the main display (3).

5) Completion of setting

1. Press the ENTER key (4). The buzzer will sound and the main display (3) will switch off.

NOTE:

If you do not press the ENTER key (4), the settings will not be memorized.

2. Turn off the power switch (1).

3. Set DIP switch No.4 to OFF.

2335M

2336M

0653B

2337M

S-7200B

11. TREADLE UNIT ASSEMBLY

60

B. For the control box panel

1) Signal setting entry

1. Turn off the power switch (1).

2. Set DIP switch No.4 to ON.

3. While pressing the end backtack key (2), turn on the power switch (1). “PF” will appear in the stitch number display (3).

2) Memorizing the maximum forward position

With the treadle depressed forward to the maximum forward position, press the start backtack key (4). “Pn” will appear in the stitch number display (3).

3193M

0652B

3195M

3196M

S-7200B

11. TREADLE UNIT ASSEMBLY

61

3) Memorizing the neutral position

With your foot released from the treadle, press the start backtack key (4). “Pr” will appear in the stitch number display (3).

4) Memorizing the maximum backward position

With the treadle depressed backward to the maximum backward position, press the start backtack key (4). The stitch number display (3) will switch off.

5) Completion of setting

1. Turn off the power switch (1).

2. Set DIP switch No.4 to OFF.

3197M

3198M

0653B

S-7200B

12. STANDING OPERATION PEDAL

62

12. STANDING OPERATION PEDAL

The foot plug assembly CDD (J04099-001) that is sold separately is required.

12-1. Installing the foot plug

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

1.

Connect the foot plug (1) to connector CN3 on the control circuit board.

2.

Connect the standing pedal connector (2) to the foot plug (1).

3.

Secure the cord (3) of the standing pedal with the shielded wire clip (5) and the cable tie (4).

0703B

S-7200B

12. STANDING OPERATION PEDAL

63

12-2. Connectors

<A> Two-step pedal Variable speed pedal

Standing operation pedal No.

9P connector 1 DC+8 V 2 High-speed switch 3 Thread trimmer switch 4 SOV 5 Spare 6 Low-speed switch 7 Presser foot switch 8 Variable speed input 9 Ground

NOTE:

Connector types

Manufacturer Connector No. Connector terminal

MOLEX 1292 P 1380 TL

0702B

1868M

1867M

High speed

Thread trimming

Low speed Presser foot

High speed

Thread trimming

Low speed Presser foot

S-7200B

13. TROUBLESHOOTING

64

13. TROUBLESHOOTING

 Please check the following points before calling for repairs or service.  If the following remedies do not fix the problem, turn off the power switch and consult a qualified technician or the place of

purchase.

DANGER

Wait at least 5 minutes after turning off the power switch and disconnecting the power cord from the wall outlet before opening the face plate of the control box. Touching areas where high voltages are present can result in severe injury.

CAUTION

Turn off the power switch and disconnect the power cord before carrying out troubleshooting. The machine may operate if the treadle is depressed by mistake, which could result in injury.

13-1. Sewing

Problem Possible cause Page

1 Upper thread is not tight.  Is the upper thread tension too weak, or is the lower thread tension

too strong?

Adjust the upper thread tension or lower thread tension.

 Is the needle and feed timing correct?

Advance the needle timing.

Instruction

manual

2 Lower thread is not tight.  Is the lower thread tension too weak, or is the upper thread tension

too strong?

Adjust the lower thread tension or upper thread tension.

Instruction

manual

3 Loops appear in seam.  Is the thread path not smooth enough?

Use a file with a fine grain or sandpaper to polish smooth the thread path.

 Is the bobbin not turning smoothly?

Pull out the lower thread to check that there is no slackness in the thread tension, or replace the bobbin or bobbin case.

4 Skipped stitches occur

while sewing

 Is the needle tip bent? Is the needle tip blunt?

If the needle tip is bent or blunt, replace the needle.

 Is the needle properly installed?

If it is incorrect, install the needle correctly.

 Is the machine properly threaded?

If it is incorrect, thread the thread correctly.

 Is the presser foot pressure too weak?

Adjust the presser foot pressure.

 Is the needle too thin?

Replace the needle with a needle that is one rank thicker.

 Is the presser foot too high?

Adjust the height of the presser foot.

 Is the thread take-up spring too weak?

Adjust the tension of the thread take-up spring.

 Is the needle and rotary hook timing correct?

Adjust the height of the needle bar. Adjust the clearance between the needle and the tip of the rotary hook.

Instruction

manual

Instruction

manual

Instruction

manual

27

26

30

31

0573M

0574M

0977M

0470M

S-7200B

13. TROUBLESHOOTING

65

Problem Possible cause Page

5 Skipped stitches at sewing

start

Thread unravelling at sewing start

 Is the thread take-up spring tension too strong?

Reduce the tension of the thread take-up spring.

 Is the thread take-up spring operating range too large?

Lower the position of the thread take-up spring.

 Are the trailing lengths of the upper threads too short after thread

trimming?

Adjust the pretension.

 Are the threads not being trimmed cleanly?

Sharpen the fixed knives, or replace the fixed and movable knives if necessary.

 Is the needle too wide?

Try using a needle with a count that is one lower than the current needle.

 Is the length of thread trailing out from the bobbin case after thread

trimming too short.

If the bobbin is spinning loosely, replace the anti-spin spring in the bobbin case.

 Is the sewing speed too fast at the sewing start?

Use the slow start feature.

 Is the needle up stop position too high?

Adjust the needle up stop position.

26

Instruction

manual

Instruction

manual

Instruction

manual

34, 35

6 Uneven seam  Is the presser foot pressure too weak?

Adjust the presser foot pressure.

 Is the feed dog too low?

Adjust the feed dog height.

 Is the bobbin scratched?

If the bobbin is damaged, smooth it with an oiled grindstone or replace it.

Instruction

manual

28

7 Large degree of puckering

(excess tension)

 Is the upper thread tension too strong?

Make the upper thread tension as weak as possible.

 Is the lower thread tension too strong?

Make the lower thread tension as weak as possible.

 Is the needle tip blunt?

Replace the needle if it is blunt.

 Is the needle too thick?

Replace with as thin a needle as possible.

 Are the thread take-up spring tensions too strong?

Make the thread take-up spring tension as weak as possible.

 Is the thread take-up spring operating range too large?

Lower the position of the thread take-up spring to as low a position as possible.

 Is the presser foot pressure too strong?

Adjust the presser foot pressure.

 Is the sewing speed too fast?

Use the sewing speed control keys to gradually reduce the sewing speed.

 Is the angle of the feed dog correct?

Tilt the front of the feed dog down slightly.

Instruction

manual

Instruction

manual

26

Instruction

manual

Instruction

manual

29

8 Material slippage  Is the presser foot pressure too strong?

Adjust the presser foot pressure.

Instruction

manual

0749M

0473M

0978M

0750M

S-7200B

13. TROUBLESHOOTING

66

Problem Possible cause Page

9 Lower thread is tangled at

the sewing start.

Spinning of bobbin during thread trimming

 Is the bobbin spinning direction correct when the lower thread is

being pulled?

Set the bobbin so that it turns in the opposite direction to the rotary hook.

 Is there too much thread

wound onto the bobbin?

The bobbin winding amount should not be more that 80 %.

 Is

the anti-spin spring attached?

Attach the anti-spin spring.

 Is the bobbin turning smoothly?

If the bobbin is not turning smoothly, replace the bobbin.

 Is a bobbin other that the light-alloy bobbins specified by Brother

being used?

Use only bobbins which are specified by Brother.

Instruction

manual

Instruction

manual

Instruction

manual

Instruction

manual

10 Upper and lower threads

are breaking.

 Is the needle tip bent? Is the needle tip blunt?

If the needle tip is bent or blunt, replace the needle.

 Is the needle properly installed?

If it is incorrect, install the needle correctly.

 Is the machine properly threaded?

If it is incorrect, thread the thread correctly.

 Is the rotary hook sufficiently lubricated? (-[]0[], []3[] specifications)

If the oil gauge is down to the lower reference line in the oil gauge window, add more oil.

 Is the upper or lower thread tension too weak or too strong?

Adjust the upper thread or lower thread tension.

 Is the upper thread may be loose because the thread take-up spring

operating range is too small?

Adjust the position of the thread take-up spring.

 Is the rotary hook, feed dog or other part damaged?

If they are damaged, smooth them with an oiled grindstone or replace the damaged parts.

 Is the thread path damaged?

If the thread path is damaged, smooth it with sandpaper or replace the damaged part.

Instruction

manual

Instruction

manual

Instruction

manual

Instruction

manual

26

11 Incorrect thread trimming

(Upper and lower threads are both not being trimmed)

 Is the fixed knife or movable knife damaged or worn?

Replace the fixed knife or the movable knife.

38

12 Incorrect thread trimming

(Upper thread or lower thread is not being trimmed)

 Is the needle properly installed?

If it is incorrect, install the needle correctly.

 Is the fixed knife or movable knife blunt?

Replace the fixed knife or the movable knife.

Instruction

manual

38

Lower

0751M

0471M

2124M

S-7200B

13. TROUBLESHOOTING

67

Problem Possible cause Page

13 Broken needles  Is the material being pushed or pulled with excessive force during

sewing?

 Is the needle properly installed?

If it is incorrect, install the needle correctly.

 Is the needle bent, is the needle tip blunt, or is the needle hole

blocked?

Replace the needle.

 Is the needle and rotary hook timing correct?

Adjust the height of the needle bar. Adjust the clearance between the needle and the tip of the rotary hook.

 Is the needle timing too advanced with respect to the feed dog?

Retard the needle timing.

 It is extremely dangerous to leave any pieces of broken

needle sticking in the material. If the needle breaks, search for all pieces until the whole of the needle is found again.

 Furthermore, we recommend that through steps be taken to

account for such needles to comply with product liability regulations.

Instruction

manual

30

31

30

14 Oil gauge (1) is not visible

in oil gauge window.

 Is the oil tank empty?

(-[]0[], []3[] specifications)

Fill the oil tank with oil.

Instruction

manual

15 Machine does not operate

when power is turned on and treadle is pressed.

 Is the power supply connector

disconnected from the control box?

Insert the connector securely.

Instruction

manual

16 Machine does not operate

at high speed.

 Is the sewing speed setting or backtack speed setting incorrect?

Use the sewing speed control keys to set the high speed.

Instruction

manual

17 Machine stops during

sewing.

 Is the fixed stitch key turned on?

Press the fixed stitch key so that the indicator turns off.

 Is the power supply voltage too low?

Check the power supply. (If the power cord is too long or too many appliances are being run from a single outlet, this may cause voltage drops which will in turn cause the reset function to activate and stop the machine, even if the power supply itself is normal.)

Instruction

manual

Caution

0469M

2195M

2196M

S-7200B

13. TROUBLESHOOTING

68

Problem Possible cause Page

18 Nothing appears on the

operation panel display.

 Is the power supply connector

disconnected from the control box?

Insert the connector securely.

 Is the operation panel

connector inside the control

box disconnected?

Insert the connector securely.

Instruction

manual

Instruction

manual

19 “GrEASEUP” or “GU”

flashes in the panel display when the power switch is turned on.

 This display is to notify you that it is time to apply grease.

Apply grease.

44, 46

2196M

3154M

S-7200B

13. TROUBLESHOOTING

69

13-2. Error code displays

If an error code appears on the operation panel display

1. Make a note of the error code and then turn off the power.

2. After the operation panel display has turned off, eliminate the cause of the error and then turn the power back on.

Error code Possible cause Page

Err 1

(Overvoltage)

 Does the power supply voltage match the

control box voltage specifications?

Check the voltage.

 Is the power supply voltage abnormally high?

Check.

 Problem with control box.

Replace the control box.

50

49

Err 2

(Overcurrent)

 Is the electrical equipment connector inside

the control box disconnected?

Insert the connector securely.

52

Err 3

(Encoder error)

 Is the encoder connector inside the control

box disconnected?

Insert the connector securely.

52

Err 4

(Motor lock)

 Is the motor connector disconnected from the

control box?

Insert the connector securely.

 Has the machine locked up?

Turn off the power and then turn the machine pulley by hand and check that it turns easily.

49

2198M

2199M

Voltage rating label

2202M

3155M

3156M

S-7200B

13. TROUBLESHOOTING

70

Error code Possible cause Page

Err 5

(Safety switch operated)

 Is the machine connector inside the control

box disconnected?

Insert the connector securely.

 Is

the machine head tilted back?

Return the machine head to its normal position. Check the operation of the safety switch.

52

25

Err 6

(Voltage drop)

 Was the power turned on while the treadle was still depressed?

Return the treadle to the neutral position, and then turn on the power switch.

 Is the power supply voltage too low?

Check the power supply voltage.

54

Err 7

(Panel communication error)

This is displayed when there is a problem communicating with the operation panel CPU.

 Is the operation panel connector inside the control box disconnected?

Insert the connector securely.

 Problem with operation panel or control box.

Replace the operation panel or control box.

52

49

Err 8

(Over time)

 This appears on the display when the sewing machine has been operating

continuously for 3 minutes or more.

Turn the power switch off and then back on again, and then operate the sewing machine normally.

Err 9

(Motor overheating abnormally)

 This is displayed when the motor becomes abnormally hot and the temperature

protection has activated.

After the temperature has dropped, turn the power switch back on and operate the sewing machine as normal.

 Problem with motor.

Replace the motor.

39

Err 10

(Solenoid overcurrent)

 This is displayed when there is overcurrent in any of the solenoids (thread trimming,

thread wiping, quick reverse or presser lifter).

Check the resistances of the solenoids.

 Problem with control P.C. board.

Replace the control box.

55

49

Err 11

(Problem with motor overheating sensor)

 Is connector CN5 inside the motor disconnected?

Insert the connector securely.

3157M

3154M

3116M

S-7200B

13. TROUBLESHOOTING

71

Error code Possible cause Page

Err 12

(Solenoid power supply error)

 Is solenoid fuse F2 (5A) blown?

Replace the fuse.

 Problem with control P.C. board.

Replace the control box.

53

49

Err 13

(Treadle unit error)

 Is the treadle unit connector inside the control

box disconnected?

Insert the connector securely.

 Is there an open circuit in the treadle

connector harness?

Replace the treadle unit.

52

Err 14

(Head detector unit error)

 Problem with head detector unit

Check that the head detector unit connector inside the control box is securely inserted. Replace the head detector unit.

52

Err 15

(Problem with sewing machine motor operation)

 Problem with motor.

Replace the motor.

 Problem with power P.C. board.

Replace the control box.

39

49

Err 16

(Thread trimming solenoid timeout)

 This is displayed if the sewing machine motor locks during thread trimming.

Remove any thread scraps that may be blocking the motor. Check that there are no problems with the thread trimming mechanism.

Err 18

(EEROM error)

 This is displayed if data could not be correctly read from or written to the memory

element on the control P. C. board.

Replace the control box.

49

Err 19

(Control box overheating)

 This is displayed when the control box becomes abnormally hot. (Three-phase

high-voltage specifications only)

Check that there are no problems with the cooling fan. If there is a problem, replace the cooling fan.

Err 20

(Treadle pedal position error)

 The settings in “Setting method for standard depression stroke” may be incorrect.

Redo the settings in “Setting method for standard depression stroke”.

 Problem with treadle unit.

Replace the treadle unit.

58, 60

3703M

3702M

3158M

S-7200B

13. TROUBLESHOOTING

72

Error code Possible cause Page

Err 21

(Thermistor error)

 Is connector CN16 inside the control box

disconnected?

Insert the connector securely.

52

Err 100 (GrEASEUP)

 This appears on the display when the sewing machine has continued to be used for

a certain period after the “GrEASEUP” notification appears without the grease being applied (without the reset procedure being carried out).

Apply grease and then carry out the reset procedure.

44

Err 101 (diP SW4)

 Is DIP switch No.4 inside the control box set

to ON?

Set DIP switch No.4 to OFF.

4

If an error code that is not listed above appears or if carrying out the specified remedy does not solve the problem, contact the place of purchase.

3160M

3159M

S-7200B

13. TROUBLESHOOTING

73

If an error code is displayed on the control box panel

1. Make a note of the error code and then turn off the power.

2. After the display of the control box panel turns off, eliminate the cause of the error and

then turn the power switch back on.

I

Error code Possible cause Page

-0

(Grease up)

 If you continue to use the sewing machine for a certain length of time without applying

grease (and without carrying out the reset operation) after “GU” has appeared on the control box panel, this will be displayed.

Apply grease and then carry out the reset procedure.

46

-1

(Dip switch 4)

 Is DIP switch No.4 inside the control box set to

ON?

Set DIP switch No.4 to OFF.

4

1

Overvoltage

2

Overcurrent

3

Encoder error

4

Motor lock

5

Safety switch operated

6

Voltage drop

7

Panel communication error

8

Over time

9

Motor overheating abnormally

10

Solenoid overcurrent

11

Problem with motor overheating sensor

12

Solenoid power supply error

13

Treadle unit error

14

Head detector unit error

15

Problem with sewing machine motor operation

16

Thread trimming solenoid timeout

18

EEROM error

19

Control box overheating

20

Treadle pedal position error

21

Thermistor error

Refer to pages 69-72 for the items corresponding to these error codes.

If an error code that is not listed above appears or if carrying out the specified remedy does not solve the problem, contact the place of purchase.

(Error code)

3161M

3160M

S-7200B

14. SEGMENT DISPLAY DEFINITION TABLE

74

14. SEGMENT DISPLAY DEFINITION TABLE

LCD display character list

1203B

S-7200B

MEMO

75

S-7200B

MEMO

76

SERVICE MANUAL

S-7200B

I6100914B

2007. 03. B (1)

Printed in Japan

Brother S-7200B, MD-741B, MD-751B, MD-741C, MD-751C Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual