Brother FD4-B272, KE-435B Owner's Manual

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T-8421C, 8422C T-8452C, 8722C

INSTRUCTION MANUAL

T-8752C

Please read this manual before using the machine. Please keep this manual within easy reach for quick reference.

TWIN NEEDLE DIRECT DRIVE LOCK STITCHER

Thank you very much for buying a BROTHER sewing machine. Before using your new machine, please read the safety instructions below and the explanations given in the instruction manual.

With industrial sewing machines, it is normal to carry out work while positioned directly in front of moving parts such as the needle and thread take-up, and consequently there is always a danger of injury that can be caused by these parts. Follow the instructions from training personnel and instructors regarding safe and correct operation before operating the machine so that you will know how to use it correctly.

SAFETY INSTRUCTIONS

[1] Safety indications and their meanings

This instruction 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.

Indications

DANGER

CAUTION

Symbols

· · · · ·

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

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.

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”.)

T-8421C, 8422C, 8452C, 8722C, 8752C

[2] Notes on safety

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

DANGER

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.

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 approximately 50 kg (110 lb). The installation should be carried out by two or more people.

Do not connect 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.

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

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

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

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.

T-8421C, 8422C, 8452C, 8722C, 8752C

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.

y When threading the needle y When replacing the bobbin and needle y 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.

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.

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

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.

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

If an error occurs in machine operation, 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

Use only the proper replacement parts as specified by Brother.

Maintenance and inspection

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.

y When carrying out inspection, adjustment and

maintenance

y When replacing consumable parts such as the

rotary hook

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

T-8421C, 8422C, 8452C, 8722C, 8752C

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

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.

iii

[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.

Touching areas where high voltages are present can result in severe injury. Turn off the power before opening the cover.

Be careful not to get your hands caught when returning the machine head to its original position after it has been tilted.

Be careful to avoid injury from the moving thread take-up.

* Safety devices: (A) Finger guard

(B) Thread take-up cover

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.

Direction of operation

T-8421C, 8422C, 8452C, 8722C, 8752C

Oil pan

Control box

Oil tank

Transformer box (100V/400V system only)

2166B

2506B

T-8421C, 8422C, 8452C, 8722C, 8752C

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

2. NAMES OF MAJOR PARTS ................ 3

3. INSTALLATION.................................... 4

3-1. Table processing diagram .............................. 5

3-2. Installation ...................................................... 5

3-3. Lubrication ...................................................... 9

3-4. Connecting the cords...................................... 11

3-4-1. Opening the control box cover............ 11

3-4-2. Connecting the cords .......................... 11

3-5. Test operation (Operating the treadle) ........... 16

3-6. Adjusting the treadle operation....................... 17

4. PREPARATION BEFORE SEWING.....18

4-1. Installing the needle........................................... 18

4-2. Removing the bobbin...................................... 19

4-3. Winding the lower thread................................ 20

4-4. Installing the bobbin........................................ 21

4-5. Threading the upper thread............................ 23

4-6. Adjusting the stitch length............................... 25

4-7. Using the knee lifter........................................ 25

4-8. Using the thread wiper

(models with thread trimmer only) .................. 25

4-9. Corner sewing method (T-8452C, 8752C) ..... 26

4-9-1. To stop the needle bars

(right and left) ..................................... 26

4-9-2. Number of stitches: quick-reference

guide ................................................... 26

5. USING THE G50 OPERATION PANEL

(BASIC OPERATIONS) ........................27

5-1. Names and functions...................................... 27

5-2. Sewing start and end backtack stitches ......... 29

5-3. Sewing continuous backtack stitches............. 30

5-4. Sewing fixed stitches ...................................... 31

5-5. Sewing pleat presser stitches......................... 32

5-6. Using the lower thread counter ...................... 33

6. USING THE G50 OPERATION PANEL

(ADVANCED OPERATIONS)...............34

6-1. Names and functions ......................................34

6-2. Adjusting the needle up stop position .............35

6-3. LOCK key........................................................36

6-4. Resetting all settings to their defaults .............37

7. USING THE G10 OPERATION PANEL

(BASIC OPERATIONS)........................ 38

7-1. Names and functions ......................................38

7-2. Sewing start and end backtack stitches..........39

7-3. Sewing continuous backtack stitches .............40

8. USING THE G10 OPERATION PANEL

(ADVANCED OPERATIONS)...............41

8-1. Changing the needle stop position .................41

8-2. Slow start ........................................................42

8-3. Correction sewing ...........................................43

8-4. Thread trimming lock

(models with thread trimmer only)...................44

8-5. Setting the maximum sewing speed ...............45

8-6. Adjusting the needle up stop position .............46

8-7. Lock function...................................................47

8-8. Resetting all settings to their defaults .............47

9. SEWING ...............................................48

9-1. Sewing ............................................................48

9-2. Backtacking.....................................................49

9-3. Sewing condensed stitches ............................50

10. THREAD TENSION ............................51

10-1. Adjusting the thread tension .........................51

10-2. Adjusting the presser foot pressure ..............52

10-3. Adjusting the presser foot floating amount

(minute lifting amount) ..................................53

10-4. Adjusting the trailing length after thread

trimming (models with thread trimmer only)

......................................................................53

10-5. Adjusting the thread take-up amount............54

T-8421C, 8422C, 8452C, 8722C, 8752C

11. CLEANING .........................................55

11-1. Daily cleaning procedures ............................ 55

11-2. Lubricating via the oil cover

(every 6 months)........................................... 56

11-3. Applying grease (Semi dry

specifications) [When “GrUP” appears

... When using the G50 operation panel]...... 57

11-4. Applying grease (Semi dry

specifications) [When “GrUP” appears

... When using the G10 operation panel]...... 60

12. ADJUSTING THE ROTARY HOOK

LUBRICATION AMOUNT...................

13. STANDARD ADJUSTMENT...............64

13-1. Safety switch position ................................... 64

13-2. Thread take-up amount for thread take-up

spring............................................................ 65

13-3. Thread take-up spring tension...................... 66

13-4. Clearance between rotary hook and needle

plate.............................................................. 67

13-5. Clearance between rotary hook and

opener .......................................................... 68

13-6. Presser foot height .......................................68

13-7. Needle and rotary hook timing ..................... 69

13-8. Installing the feed dog ..................................71

13-9. Feed dog position ......................................... 72

13-10. Feed dog height.......................................... 73

13-11. Feed dog angle........................................... 74

14. TROUBLESHOOTING........................75

14-1. Sewing.......................................................... 75

14-2. Error code displays....................................... 80

15. 7-SEGMENT DISPLAY.......................84

T-8421C, 8422C, 8452C, 8722C, 8752C

1. MACHINE SPECIFICATIONS

B C D E F

4 7

Rotary hook Standard hook Large hook

2 5

Stitch function Fixed needle bar Split needle bar

1 2

Thread trimmer -

4 T

Quick reverse

Thread wiper

0 3

Lubrication type Minimum lubrication Semi dry

F 3 5 7

Use Foundation

○ ○ ○

Light-weight and

medium-weight

materials

Heavy-weight

materials

2167B

○

Heavy-weight

materials

(For extra thick

thread)

T-8421C, 8422C, 8452C, 8722C, 8752C

1. MACHINE SPECIFICATIONS

T-8421C

-T3F -T0F -T33 -T03 Max. sewing speed 3,000 sti/min 4,000 sti/min 3,000 sti/min 4,000 sti/min Start backtacking and continuous backtacking speed

250–1,800 sti/min

End backtacking speed 1,000 sti/min Max. stitch length 4 mm

Lifting lever 7 mm Presser foot

height

Knee lifter 13 mm Feed dog height 1 mm Needle (DP×5)

#9–#14 #11–#16 Motor AC servo motor (4-pole, 550W) Control circuit Microprocessor

T-8422C

-403 -433 -405, -407 Max. sewing speed 4,000 sti/min 3,000 sti/min Start backtacking and continuous backtacking speed

250–1,800 sti/min

End backtacking speed 1,000 sti/min Max. stitch length 4 mm 5 mm

Lifting lever 7 mm Presser foot

height

Knee lifter 10 mm Feed dog height 1 mm Needle (DP×5)

#11–#16 #14–#22 Motor AC servo motor (4-pole, 550W) Control circuit Microprocessor

T-8452C

-403 -405, -407 Max. sewing speed 3,000 sti/min Start backtacking and continuous backtacking speed

250–1,800 sti/min

End backtacking speed 1,000 sti/min Max. stitch length 5 mm

Lifting lever 7 mm Presser foot

height

Knee lifter 10 mm Feed dog height 1 mm Needle (DP×5)

#11–#16 #14–#22 Motor AC servo motor (4-pole, 550W) Control circuit Microprocessor

T-8722C, 8752C

-403 -405, -407 Max. sewing speed 3,000 sti/min Start backtacking and continuous backtacking speed

250–1,800 sti/min

End backtacking speed 1,000 sti/min Max. stitch length 7 mm

Lifting lever 7 mm Presser foot

height

Knee lifter 10 mm Feed dog height 1 mm Needle (DP×5)

#11–#16 #14–#22 Motor AC servo motor (4-pole, 550W) Control circuit Microprocessor

T-8421C, 8422C, 8452C, 8722C, 8752C

2. NAMES OF MAJOR PARTS

G50 operation panel (advanced function LCD)

G10 operation panel (basic function LED)

(1) Bobbin winder (2) Thread wiper (T-8422C, 8452C, 8722C, 8752C) (3) Lifting lever (4) Quick reverse (Actuator switch) (5) Presser foot (6) Control box (7) Knee lifter assembly (8) Power switch

(9) Stitch length dial (10) Reverse lever (11) Oil gauge window (12) Machine pulley (13) Operation panel (14) Cotton stand (15) Stop lever (T-8452C, 8752C )

Safety devices

(16) Thread take-up cover (17) Finger guard

2168B

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

CAUTION

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 approximately 50 kg (110 lb). The installation should be carried out by two or more people.

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

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.

3. INSTALLATION

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

2086M

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.

2169B

2871M

2872M

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

3-1. Table processing diagram

 The top of the table should be 40 mm in thickness and should be strong enough to hold the weight and with-stand the

vibration of the sewing machine.

 Drill holes as indicated in the illustration below.

Control box mounting hole

Head rest hole

Cotton stand hole

Cord hole

2170B

3-2. Installation

1. Control box

(1) Control box (2) Bolts [3 pcs] (3) Nuts [3 pcs] (4) Spring washers [3 pcs] (5) Washers [3 pcs]

2. Connecting rod

(6) Connecting rod (7) Nut

4127M

T-8421C, 8422C, 8452C, 8722C, 8752C

2874M

2875M

3. INSTALLATION

3. Oil pan

(1) Head cushions (left) [2 pcs] (2) Head cushions (right) [2 pcs] (3) Oil pan (4) Oiler

4. Rubber cushions

(1) Rubber cushions [2 pcs] (2) Nails [4 pcs]

5. Knee lifter complying bar

(3) Knee lifter complying bar

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

2171B

2172B

6. Machine head

(1) Hinges [2 pcs] (2) Machine head (3) Head rest

NOTE:

 Tap the head rest (3) securely into

the table hole.

 If the head rest (3) is not pushed in

as far as it will go, the machine head will not be sufficiently stable when it is tilted back.

7. Operation panel

(1) Operation panel (2) Screws [2 pcs]

(Use for tightening rear cover)

8. Cotton stand

(1) Cotton stand

NOTE:

Securely tighten the nut (4) so that the two rubber cushions (2) and the washer (3) are securely clamped and so that the cotton stand (1) does not move.

2878M

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

9. Knee lifter plate

(1) Knee lifter plate (2) Bolt

* Loosen the bolt (3) and the bolt (4),

and move the knee lifter plate (1) to a position where it is easy to use.

2173B

1. Turn the machine pulley so that the feed dog is below the top of the needle plate.

2. Lower the presser foot (5) by using the lifting lever (4).

2880M

2881M

3. Loosen the nut (6).

4. Turn the screw (8) to adjust so that the amount of play in the knee lifter (7) is approximately 2 mm when the knee lifter plate (1) is gently pressed.

5. Securely tighten the nut (6).

6. Loosen the nut (9).

7. Turn the screw (10) until the distance between the end of the screw (10) and the knee lifter (7) is approximately 5 mm.

8. Turn the adjusting screw (10) to adjust so that the presser foot (5) is at the desired position within a distance of 13 mm of the needle plate when the knee liter plate (1) is fully pressed.

9. After adjustment is completed, securely tighten the nut (9).

Within 13 mm

2882M

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

3-3. Lubrication

Do not connect the power cord until lubrication has been completed, otherwise the machine may operate if the treadle is depressed by mistake, which could result in injury.

When cutting the nozzle of the oil tank, hold the base of the nozzle securely. If you hold the end of the nozzle, injury from the scissors may result.

CAUTION

 The sewing machine should always be lubricated and the

oil supply replenished before it is used for the first time, and also after long periods of non-use.

 Use only the lubricating oil <NIPPON OIL CORPORATION

Sewing Lube 10N; VG10> specified by Brother.

* If this type of lubricating oil is difficult to obtain, the recommended

oil to use is <Exxon Mobil Essotex SM10; VG10>.

1. Hold the base of the nozzle of the accessory oil tank (1), and use scissors to cut about half-way along the straight section (A) of the nozzle.

2354B

2. Loosen and remove the nozzle, and then remove the seal (2).

3. Tighten the nozzle.

1. Tilt back the machine head.

2. Remove the rubber cap (1).

3. Use the accessory oil tank (2) to pour lubricating oil into the oil cover (3) until the oil level reaches the reference line (4).

NOTE:

Do not fill with lubricating oil past the reference line (4). If you pour in too much lubricating oil, it may spill out when the machine head is tilted back.

4. Replace the rubber cap (1).

5. Return the machine head to its original position.

* If the lubricating oil level drops below the bottom (6) of the

oil gauge window (5), be sure to add more oil.

2355B

1. Remove the rubber cap (1).

2. Use the accessory oil tank (2) to pour in lubricating oil until the oil level reaches the top reference line (4) of the oil gauge window (3).

3. Replace the rubber cap (1).

* If the lubricating oil level drops below the bottom reference

line (5), be sure to add more oil.

2356B

T-8421C, 8422C, 8452C, 8722C, 8752C

■Lubrication

Apply 1 - 2 drops of oil to the places indicated by the arrows.

Rotary hook race (left and right)

3. INSTALLATION

* Do not apply oil for semi dry types.

<T-8452C, 8752C>

2200B

2174B

T-8421C, 8422C, 8452C, 8722C, 8752C

2887M

3. INSTALLATION

3-4. Connecting the cords

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

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

Do not connect the power cord until all cords have been connected. The machine may operate if the treadle is depressed by mistake, which could result in injury.

3-4-1. Opening the control box cover

3-4-2. Connecting the cords

T-8421C, 8422C, 8452C, 8722C, 8752C

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.

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.

(1) Screw (2) Cover

4137M

1. Sewing machine cords

2175B

Lower the tab (6).

Push in securely until the tabs (6) engage.

Cords

Press the tab.

Raise the tab (6).

4139M

4140M

4141M

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

(1) 6-pin head detector unit connector (2) 12-pin operation panel connector (3) 10-pin resolver connector (4) 14-pin machine connector (5) 4-pin motor connector

2. Binding the cords

(1) Repeat cable tie

NOTE:

 Bind the cords in such a way that the

connector does not get pulled out.

 All cords that come out from the

control box should be secured to the cord holder (2) using the repeat cable tie (1), otherwise vibration from the sewing machine may cause the cords to become disconnected, which can cause problems with the operation of the control box.

3. INSTALLATION

4143M

3. Ground wire

(1) Ground wire (2) Washer (3) Spring washer (4) Screw

Oil pan

Ground symbol Ground symbol

2176B

4. Other cords

Connect cords that match the voltage specifications.

Control box

Green and yellow wire (ground wire)

Leg

< Europe specifications >

(1) Filter box (2) Screws [4 pcs.] (3) Staples [7 pcs.] (4) Power cord

1. Attach an appropriate plug to the power cord (4). (The green and yellow wire is the ground wire.)

2. Insert the power plug into a properly-grounded electrical outlet.

NOTE:

 Take care when tapping in the

staples (3) to make sure that they do not pierce the cords.

 Do not use extension cords,

otherwise machine operation problems may result.

4144M

T-8421C, 8422C, 8452C, 8722C, 8752C

Operator

Green and yellow wire (ground wire)

4145M

2177B

2178B

3. INSTALLATION

<200V system>

(1) Power switch (2) Screws [2 pcs]

(3) 3-pin power supply connector (4) Power cord (5) Staples [5 pcs.]

1. Attach an appropriate plug to the power cord (4). (The green and yellow wire is the ground wire.)

2. Insert the power plug into a properly-grounded electrical outlet.

NOTE:

 Take care when tapping in the

staples (5) to make sure that they do not pierce the cords.

 Do not use extension cords,

otherwise machine operation problems may result.

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

Operator

Green and yellow wire (ground wire)

T-8421C, 8422C, 8452C, 8722C, 8752C

4145M

2179B

2380B

<100V/400V system>

(1) Power switch (2) Screws [2 pcs]

(3) Transformer box (4) Transformer box plates [2 pcs.] (5) Screw [with washer] (6) 3-pin power supply connector (7) Staples [6 pcs.] (8) Cord clamps [2 pcs.] (9) Power cord

1. Attach an appropriate plug to the

power cord (9). (The green and yellow wire is the ground wire.)

2. Insert the power plug into a

properly-grounded electrical outlet.

NOTE:

 Take care when tapping in the

staples (7) to make sure that they do not pierce the cords.

 Do not use extension cords,

otherwise machine operation problems may result.

3-5. Test operation (Operating the treadle)

CAUTION

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.

3. INSTALLATION

2114M

2182B

2207B

2117M

Press the ON power switch (1). The power indicator (2) will illuminate.

1. Check that the machine sews at low speed when the treadle (3) is gently pressed to position (B).

NOTE:

If the sewing machine does not operate even when the treadle (3) is depressed, check the position of the safety switch. (Refer to “13-1. Safety switch position”.)

2. Then check that it sews at high speed when the treadle (3) is gently pressed to position (C).

3. After pressing the treadle (3) forward, check that the needle is lowered to the top of the needle plate when the treadle (3) is returned to the neutral position (A). (when needle down stopping has been set.)

4. If the treadle (3) is pressed to position (D), (thread trimming is carried out for models with thread trimmer) and the needle rises above the needle plate and stops.

5. With the machine head tilted back, depress the treadle (3)

and check that the sewing machine does not operate.

NOTE:

If the sewing machine operates when the treadle (3) is depressed while the machine head is tilted back, the safety switch is probably faulty. Contact the place of purchase.

T-8421C, 8422C, 8452C, 8722C, 8752C

3. INSTALLATION

3-6. Adjusting the treadle operation

4259M

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, c and d 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.

4260M

T-8421C, 8422C, 8452C, 8722C, 8752C

4. PREPARATION BEFORE SEWING

4-1. Installing the needle

CAUTION

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

4. PREPARATION BEFORE SEWING

<T-8421C, 8422C, 8722C>

<T-8452C, 8752C>

1. Turn the machine pulley to move the needle bar to its highest position.

2. Loosen the screws (1).

3. Insert the needle (2) straight in as far as it will go so that the long groove is facing inward, and then securely tighten the screws (1).

Long groove

2461B

Long groove

2462B

T-8421C, 8422C, 8452C, 8722C, 8752C

4. PREPARATION BEFORE SEWING

4-2. Removing the bobbin

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

CAUTION

1. Open the slide plates (1) by moving them to the right and left.

2. Pull the rotary hook latches (2) upward, and them remove the bobbins (3).

2463B

2464B

1. Open the slide plates (1) by moving them to the right and left.

2. Lift up the latch (2) of the rotary hook, and then remove the bobbin case (3).

3. Remove the bobbin.

T-8421C, 8422C, 8452C, 8722C, 8752C

4-3. Winding the lower thread

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

4. PREPARATION BEFORE SEWING

CAUTION

2897M

Less thread

More thread

1. Turn on the power switch.

2. Place the bobbin (1) onto the bobbin winder shaft (2).

3. Wind the thread several times around the bobbin (1) in the direction indicated by the arrow. * Check that the thread is not loose anywhere along the

thread path.

4. Push the bobbin presser arm (3) toward the bobbin (1).

5. Raise the presser foot with the lifting lever.

6. Depress the treadle. Lower thread winding will then start.

7. Once winding of the lower thread is completed, the bobbin presser arm (3) will return automatically.

8. After the thread has been wound on, remove the bobbin and cut the thread with the knife (4).

* Loosen the screw (5) and move the bobbin presser (6) to

adjust the amount of thread wound onto the bobbin.

NOTE:

The amount of thread wound onto the bobbin should be a maximum of 80 % of the bobbin capacity.

2124M2123M

T-8421C, 8422C, 8452C, 8722C, 8752C

4. PREPARATION BEFORE SEWING

4-4. Installing the bobbin

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

CAUTION

2898M

2465B

2900M

1. Insert the bobbin (1) into the rotary hook (2) so that the winding direction is as shown in the illustration.

2. Return the rotary hook latch (3) to its original position.

3. Turn the machine pulley to rotate the rotary hook (2) until the tension spring (4) is visible.

4. Pass the thread through slit (5) in the rotary hook and then pass it under the thread tension spring.

5. Pull out the thread to a length of approximately 50 mm.

6. Close the slide plates.

 There is an anti-spin spring (6) inside the rotary hook. The

anti-spin spring (6) prevents the bobbin from racing at times such as during thread trimming.

 Use bobbins (1) made of light alloy as specified by

BROTHER.

2466B

T-8421C, 8422C, 8452C, 8722C, 8752C

<A>

<B>

<C>

4. PREPARATION BEFORE SEWING

1. Insert the bobbin (1) into the bobbin case (2) so that the winding direction is as shown in the illustration.

2. There are three types of cap (2) (<A>, <B> and <C>).

Thread the thread by one of the following methods in accordance with the shape of the bobbin case (2) being used.

<A>

1) Pass the thread through slot (3) and under the thread tension spring (4).

2) Pass the thread through the thread hole (8) and pull

2902M

out about 50 mm.

<B> <C>

1) Pass the thread through slot (3) and under the thread tension spring (4).

2) Pass the thread through slots (5) and (6), and then through the spring (7).

3) Pass the thread through the thread hole (8) and pull out about 50 mm.

3. Insert the bobbin case (2) into the rotary hook.

4. Push latch (9) of the rotary hook flat.

5. Close the slide plates.

3126M

3127M

2467B

 There is an anti-spin spring (10) inside the rotary hook. The

anti-spin spring (10) prevents the bobbin from racing at times such as during thread trimming.

 Use bobbins (1) made of light alloy as specified by

BROTHER.

2468B

T-8421C, 8422C, 8452C, 8722C, 8752C

4. PREPARATION BEFORE SEWING

4-5. Threading the upper thread

CAUTION

Turn off the power switch before threading the upper thread. The machine may operate if the treadle is depressed by mistake, which could result in injury.

・ Turn the machine pulley and raise the thread take-up (1) before threading the upper thread.

This will make threading easier and it will prevent the thread from coming out at the sewing start.

・ Thread the left-side thread first.

T-8421C, 8422C, 8452C, 8722C, 8752C

4. PREPARATION BEFORE SEWING

Do not pass the thread through.

Center

Pass the thread through.

(Refer to p.54)

If the tension discs are opened as follows, the thread will become easier to thread.

Press the tension release plate (2).

Press the tension release plate (2), or operate the lifting lever or the knee lifter to raise the presser foot.

The thread can be passed securely in between the tension discs.

Pass the thread on the inside of the tab (3).

Specifications indicated by the * mark include arm thread guide D (4) and felt (5). When using polyester thread, install these components and thread the thread as shown in the illustration.

2183B

T-8421C, 8422C, 8452C, 8722C, 8752C

4. PREPARATION BEFORE SEWING

4-6. Adjusting the stitch length

1. Unlock the stitch length dial (2) by turning the dial lock lever (1) to the right until a click is heard.

2. Turn the stitch length dial (2) clockwise or counterclockwise so that the desired stitch length is at the uppermost position on the dial.  The larger the number, the longer the stitch length will be.

(The numbers on the dial are for use as a guide. The length of the finished stitches may vary depending on the type and thickness of material being sewn. Adjust while looking at the finished stitches.)

 When turning the stitch length dial (2) from a larger

setting to a smaller setting, it will be easier to turn the dial if the reverse lever (3) is pushed to the halfwaydown position.

3. Turn the dial lock lever (1) firmly to the left to lock the stitch length dial (2).

* Check that the stitch length dial (2) does not rotate.

Locked Unlocked

2906M

4-7. Using the knee lifter

The presser foot (2) can be raised by pressing the knee lifter plate (1).

2907M

2469B

4-8. Using the thread wiper (models with thread trimmer only)

2184B

1. Press the thread wiper switch (1) to the side.

2. Press the thread wiper key (2) on the operation panel so that the indicator illuminates.

After thread trimming is carried out, the thread wiper (3) will pull up the thread.

2470B

T-8421C, 8422C, 8452C, 8722C, 8752C

4. PREPARATION BEFORE SEWING

4-9. Corner sewing method (T-8452C, 8752C)

NOTE:

If using this machine in place of a single-needle machine, remove the needle which is not being used. In such cases, do not use the procedures given below to stop the unused needle bar from moving, otherwise damage to the machine may result.

4-9-1. To stop the needle bars (right and left)

 Operate the stop lever after the needle has penetrated the

material and has stopped moving.

 Do not sew at speeds of over 1,000 sti/min while one of the

needle bars has been stopped.

Needle stop

3128M

Needle stop

3129M

Push

3130M

4-9-2. Number of stitches: quick-reference guide

Sewing angle 40°

No. of stitches 6

Determine the stitch length from the chart above to make beautiful corner stitching. The number of stitches of the outer needle varies according to the combination of sewing angle and stitch length.

[Example] For a sewing angle of 40° and a stitch length of 2.9 mm, the number of stitches becomes 6.

3131M

Sewing

angle

No. o Stitches

30° 40° 50° 60° 70° 80° 90° 100° 110° 120° 130° 140°

2 4.6 3.8 3.2 2.7 2.2 1.8 1.5 1.1 3 4.6 3.5 3.0 2.5 2.1 1.8 1.5 1.2 4 4.4 3.4 2.8 2.3 1.9 1.6 1.3 5 4.8 3.5 2.7 2.2 1.8 1.5 1.3

6 4.0 2.9 2.3 1.9 1.5 1.3 7 3.7 2.5 2.0 1.6

8 3.0 2.2 1.7

T-8421C, 8422C, 8452C, 8722C, 8752C

Move the stop lever (1) to the “L” position.

<To stop operation of the right needle bar> Move the stop lever (1) to the “R” position.

<To resume twin-needle sewing> Press the push lever (2). The stop lever (1) will then return to its original position automatically.

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

5-1. Names and functions

• The operation panel keys cannot be operated while sewing is in progress.

Select the keys and set the number of stitches before starting sewing.

• In the case of keys with indicators, the indicator illuminates when that function is operating, and the indicator switches off

when the key is pressed once more.

The power indicator illuminates when the power switch is turned on.

(1) Main display

(2) Setting keys

(3) Start backtack key

(4) End backtack key

(5) Continuous backtack key

(6) Fixed stitch key

• In start backtack display, AB illuminates and the number of stitches for A and B are displayed.

• In end backtack display, CD illuminates and the number of stitches for C and D are displayed.

• In continuous backtack display, ABCD illuminates and the number of stitches for A, B, C and D are displayed.

• In fixed stitch display, E or F illuminates and the number of stitches for E or F are displayed.

These keys are used to set the number of backtack stitches for A, B, C and D and the number of fixed stitches for E and F.

• When the key is pressed, the setting increases from 0 up to 99.

• When the key is pressed, the setting decreases from 99 down to 0.

When this key is pressed so that the indicator illuminates, the number of start backtack stitches (0−99) in the A and B stitch number displays is sewn.

When this key is pressed so that the indicator illuminates, the number of end backtack stitches (0−99) in the C and D stitch number displays is sewn. When the treadle is depressed backward, the end backtack stitches are sewn and then the thread is trimmed automatically (models with thread trimmer). If the treadle has not yet been depressed backward, the end backtack function can be set to ON, the number of stitches can be changed and the function can be set back to OFF.

When this key is pressed so that the indicator illuminates, the number of backtack stitches (0−99) in the A, B, C and D stitch number displays is sewn continuously. After the sewing machine sews a full cycle of stitches set by A, B, C and D, the thread is trimmed automatically (models with thread trimmer).

When this key is pressed so that the indicator illuminates, the number of stitches (0-1999) in the E stitch number display is sewn, and then the sewing machine stops automatically.

Power indicator

4159M

2136M

4160M 2138M 2139M

4161M

4162M

4163M

4164M

T-8421C, 8422C, 8452C, 8722C, 8752C

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

(7) Name label key

When this key is pressed so that the indicator illuminates, fixed stitch sewing of the number of stitches (0-1999) in the E and F stitch number displays is carried out repeatedly.

(8) Pleat presser sewing key

When this key is pressed so that the indicator illuminates, the number of backtack stitches (0-1999) in the E stitch number display can be sewn by pressing the actuator switch.

(9) Thread trimming key (models with thread trimmer only)

• This can only be set for use together with the fixed stitch key (6) or the name label key (7).

• When this key is pressed so that the indicator illuminates, the set number of stitches (start or end backtack stitches or fixed stitches) are sewn, and then the thread is trimmed automatically.

(10) AUTO key

• This can only be set for use together with the continuous backtack key (5), the fixed stitch key (6) or the name label key (7).

• When this key is pressed so that the indicator illuminates, the set number of stitches (start or end backtack stitches, fixed stitches or thread trimming (models with thread trimmer)) are sewn automatically simply by depressing the treadle once.

(11) Sewing speed control display

This shows the sewing speed when the treadle is depressed to the maximum amount.

• If all bars are illuminated, it indicates that the maximum speed can be set.

• If all bars are switched off, it indicates the minimum speed (250 sti/min).

(12) Sewing speed control keys

These keys let you adjust the sewing speed that is used when the treadle is depressed to the maximum amount. The sewing speed can also be adjusted while sewing is in progress.

• When the + key is pressed, the sewing speed becomes faster.

• When the - key is pressed, the sewing speed becomes slower.

(13) Thread trimming lock key (models with thread trimmer only)

• When this key is pressed so that the indicator illuminates, the sewing machine stops in the needle up position without thread trimming being carried out even if the treadle is depressed backward.

• If the indicator of the AUTO key (10) is illuminated, the sewing machine stops in the needle up position without thread trimming being carried out after the set number of stitches have been sewn.

(14) Half stitch key

When the sewing machine is stopped, the needle bar can be moved up and down by pressing this key.

(15) Lower thread counter display

This shows the lower thread counter value. The counter is reduced by “1” for every ten stitches sewn.

(16) Lower thread counter keys

These keys are used to set the initial value for the lower thread counter. (Refer to “5-6. Using the lower thread counter”.)

(17) RESET key

This key is used to return the lower thread counter to its initial value and to cancel warning conditions. (Refer to “5-6. Using the lower thread counter”.)

(18) Thread wiper key

• When this key is pressed so that the indicator illuminates, the thread wiper (-4[][]

specifications) operates. (Refer to “4-8. Using the thread wiper (models with thread trimmer only)”.)

• When the indicator of the thread trimming lock key (13) is illuminated, the thread wiper

key (18) is disabled.

• If you press the thread trimming lock key (13) so that its indicator illuminates while the

indicator of the thread wiper key (18) is illuminated, the indicator of the thread wiper key (18) will switch off.

T-8421C, 8422C, 8452C, 8722C, 8752C

4165M

4166M

4167M

4168M

4169M

4170M

4171M

4172M

2154M

4170M

4173M

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

5-2. Sewing start and end backtack stitches

Setting start backtack stitches

Setting end backtack stitches

2911M

Start backtacking is carried out. After it has finished, normal sewing continues for as long as the treadle remains depressed.

NOTE:

If the treadle is returned to the neutral position, the sewing machine will continue operating until the set number of start backtack stitches has been sewn.

End backtacking is carried out. After it has finished, the thread is trimmed automatically (models with thread trimmer) and the sewing machine stops in the needle up position.

NOTE:

• If the treadle is depressed backward before sewing of the set number of start backtack

stitches is complete, end backtacking will not be carried out.

• If the indicator of the thread trimming lock key is illuminated, the sewing machine will stop in the needle up position without thread trimming being carried out.

For example, 3 stitches and 4 stitches

4175M

Example:

4176M

2159M

2160M

T-8421C, 8422C, 8452C, 8722C, 8752C

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

5-3. Sewing continuous backtack stitches

Setting continuous backtack stitches

2185B

If the treadle is simply depressed continuously, the number of stitches set for A, B, C and D will be sewn in a single cycle, the thread will be trimmed automatically (models with thread trimmer) and then the needle bar will stop in the needle up position.

NOTE:

• If the treadle is returned to the neutral position while continuous backtacking is being carried out, the sewing machine will stop at the point where the treadle returns to the neutral position.If the treadle is depressed again, operation will resume from the point where it was interrupted.

• If the indicator of the thread trimming lock key is illuminated, the sewing machine will stop in the needle up position without thread trimming being carried out.

When the AUTO key is pressed to turn on the automatic sewing function, operation will be carried out automatically from continuous backtack sewing through to thread trimming (models with thread trimmer) just by depressing the treadle once, without needing to keep it depressed continuously.

Example:

4177M

2159M

T-8421C, 8422C, 8452C, 8722C, 8752C

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

5-4. Sewing fixed stitches

Setting the number of fixed stitches

2912M

After the set number of stitches in E (fixed stitches) have been sewn, the sewing machine stops in the needle position that has been set by the needle up/down key (refer to p. 34). After this, normal sewing is carried out if the treadle is depressed.

After the thread is trimmed (models with thread trimmer), fixed stitch sewing mode is enabled.

Press the thread trimming key to turn on the thread trimming function. When the treadle is continuously depressed, thread trimming is carried out after the fixed stitches have been sewn.

When the AUTO key is pressed to turn on the automatic sewing function, the fixed stitches are sewn simply by depressing the treadle once without needing to depress it continuously.

• The start backtack key and end backtack key can be pressed to turn on the backtack sewing function.

• If changing the number of end backtack stitches in C and D, press the fixed stitch key to temporarily turn off the fixed stitch function before making the change. (The CD display will show the number of stitches and the setting can then be changed.)

4178M

Example:

From 0 to 1999 stitches can be set.

2159M

2160M

T-8421C, 8422C, 8452C, 8722C, 8752C

5-5. Sewing pleat presser stitches

2186B

These functions cannot be used.

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

4180M

Example:

From 0 to 1999 stitches can be set.

If the treadle is continuously depressed and then you press the actuator switch while sewing is in progress, the number of backtack stitches set in E is sewn and then normal sewing resumes.

2187B

Thread trimming is carried out (models with thread trimmer).

2160M

• The start backtack key and end backtack key can be pressed to turn on the backtack sewing

function.

• If changing the number of end backtack stitches indicated in C and D, press the pleat presser

sewing key to turn off the pleat presser sewing function before making the change. (The CD display will show the number of stitches and the setting can then be changed.)

T-8421C, 8422C, 8452C, 8722C, 8752C

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

5-6. Using the lower thread counter

y The lower thread counter can be used to let you know approximately how much lower thread is remaining. y The value displayed by the lower thread counter display is reduced by 1 from the initial setting value each time the sewing

machine sews 10 stitches, and a warning is given when the counter goes below “0”.

(Press for 2 seconds or more)

1. When sewing is carried out, the value shown in the lower thread counter display is reduced by 1 for every 10 stitches sewn.

2. When the value goes below “0”, a warning icon (1) illuminates and an electronic buzzer sounds for 5 seconds.

3. Sewing will be possible even after the treadle is returned to the neutral position and the sewing machine stops. However,

4. If you press and hold the RESET key (2) for 2 seconds or more, the display will return to the initial value.

(Initial value)

(When the value goes below zero (“0”), a minus sign appears and counting continues to a maximum of “-999”.)

after the treadle has been depressed backward and thread trimming has been carried out (models with thread trimmer), sewing using the treadle will no longer be possible.

NOTE:

If the treadle is depressed after sewing is no longer possible, the buzzer will sound once and “ rESEt” will appear in green in the main display. When the treadle is returned to the neutral position, the display will return to the original display. If you press the RESET key (2), the warning icon (1) will disappear and sewing will be possible when the treadle is depressed.

Reduces by 1 for every 10 stitches sewn

After about 2 seconds, the buzzer will sound and the lower thread counter display will show the initial value which was set previously.

4182M

・ When the + key is pressed, the setting increases. ・ When the - key is pressed, the setting decreases. ・ If you hold down the keys, the setting will change more quickly. ・ If a value of “0” is set, the lower thread counter will not operate. ・ The initial setting value will be accepted when sewing starts.

4183M

(Buzzer sounds for 5 seconds)

T-8421C, 8422C, 8452C, 8722C, 8752C

Sewing is possible until thread trimming is carried out (models with thread trimmer).

Press the RESET key (2) for 2 seconds or more.

4184M

6. USING THE G50 OPERATION PANEL (ADVANCED OPERATIONS)

The operations described in this section should only be carried out by a technician.

6-1. Names and functions

(19) Slow start key

(21) Correction key

(23) Needle up/down key

• When this key is pressed so that the slow start icon (20) illuminates, the first two stitches sewn after the thread is trimmed are sewn at 700 sti/min. After this, the sewing speed corresponds to the treadle depression amount.

• If you press this key again while the icon (20) is illuminated, the icon (20) will turn off.

• When this key is pressed so that the correction icon (22) illuminates, correction sewing

can be carried out. If the sewing machine is stopped, sewing will be carried out at slow speed (250 sti/min) while the actuator switch is being pressed.

NOTE:

• If you press the actuator switch while sewing is in progress, backtack stitches will be sewn.

• Correction sewing cannot be carried out while the indicator of the pleat presser sewing key (8) is illuminated.

• If you press this key again while the icon (22) is illuminated, the icon (22) will turn off.

Use this key to select whether the needle bar stops in the up position or the down position when the treadle is returned to the neutral position and sewing stops.

• When the needle up icon

• When the needle down icon

position.

(24) is illuminated, the needle bar stops in the up position.

(25) is illuminated, the needle bar stops in the down

These are used for making advanced operating settings. They should only be used by a technician.

4185M

4186M

4187M

4188M 2207M 2208M

T-8421C, 8422C, 8452C, 8722C, 8752C

6. USING THE G50 OPERATION PANEL (ADVANCED OPERATIONS)

6-2. Adjusting the needle up stop position

(While pressing the key (1), press the power ON switch.)

Selecting “UpoS xxx”

(Press once)

Needle up stop position setting

(Setting value)

Example:

Becomes higher

Becomes lower

“MorG xxx” will appear in orange in the main display (2).

“xxx” is the setting value for the needle up stop position, and “0” is the default setting.

• If you press the key, the setting value will increase and the needle up stop position will become lower.

• If you press the key, the setting value will decrease and the needle up stop position will become higher.

• The setting range is from –5 to 10.

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

of approximately 10° for the upper shaft.

4189M 2138M

4190M

The setting values will be memorized.

* For details on other adjustment items, refer to the Service Manual.

Normal sewing machine operation will then be possible.

T-8421C, 8422C, 8452C, 8722C, 8752C

2188B 2138M 2139M

4192M

4193M

6-3. LOCK key

6. USING THE G50 OPERATION PANEL (ADVANCED OPERATIONS)

When the power switch is turned on, the LOCK key (1) turns ON. (The icon (2) is illuminated.) In this state, the following three key operations are disabled so that the setting values cannot be changed accidentally.

FUNC key (3)

This key is used to make settings for various functions.

ENTER key (4)

This key is used to accept function settings.

MAX key (5)

4194M

This key is used to change the maximum sewing speed.

* Refer to the Service Manual for details on using these

keys.

T-8421C, 8422C, 8452C, 8722C, 8752C

6. USING THE G50 OPERATION PANEL (ADVANCED OPERATIONS)

6-4. Resetting all settings to their defaults

If the sewing machine stops operating normally, the cause may be that an incorrect setting may have been made for the memory data by means of memory switches, for instance. In such cases, it may be possible to restore normal operation by following the steps given below to initialize the memory setting data.

Activating initialization mode

(While pressing the RESET key, press the power ON switch.)

“init ALL” will appear in orange in the main display (1).

4195M

(Press for 2 seconds or more)

Reference

If the X keys (2) are pressed at this time, you can select the items to be initialized as shown below. * For details on initialization items other than “init ALL”,

refer to the Service Manual.

Main display Initialization items

“ init ALL ” “ init MEM ” “ init SPd ” “ init SEW ”

Once initialization is complete, the main display will return to green.

Initialization mode will be exited and normal sewing machine operation will then be possible.

Clears all settings Initializes memory switches Initializes sewing speed Initializes programs

4196M 2138M 2139M

4192M

4193M

T-8421C, 8422C, 8452C, 8722C, 8752C

7. USING THE G10 OPERATION PANEL (BASIC OPERATIONS)

7-1. Names and functions

・ The operation panel keys cannot be operated while sewing is in progress.

Select the keys and set the number of stitches before starting sewing.

・ In the case of keys with indicators, the indicator illuminates when that function is operating, and the indicator switches off

when the key is pressed once more.

The power indicator illuminates when the power switch is turned on.

(1) Display

(2) Setting keys

(3) Start backtack key

(4) End backtack key

(5) Continuous backtack key

(6) Thread wiper key

・ When start backtack stitches are being displayed, the indicator of the start backtack key

(3) will illuminate, and the number of A stitches will appear in the A column and the number of B stitches will appear in the B column.

・ When end backtack stitches are being displayed, the indicator of the end backtack key

(4) will illuminate, and the number of C stitches will appear in the C column and the number of D stitches will appear in the D column.

・ When continuous backtack stitches are displayed, the indicator of the continuous

backtack key (5) will illuminate, and the number of A, B, C and D stitches will appear in order starting from the left column of the display.

These keys are used to set the number of backtack stitches for A, B, C and D.

・ When the key is pressed, the setting increases from 0 up to 9. ・ When the key is pressed, the setting decreases from 9 down to 0.

When this key is pressed so that the indicator illuminates, the number of start backtack stitches (0 - 9) in the A and B columns of the display are sewn.

When this key is pressed so that the indicator illuminates, the number of end backtack stitches (0 -

9) in the C and D columns of the display are sewn. When the treadle is depressed backward, the end backtack stitches are sewn and then the thread is trimmed automatically (models with thread trimmer). If the treadle has not yet been depressed backward, the end backtack function can be set to ON, the number of stitches can be changed and the function can be set back to OFF.

When this key is pressed so that the indicator illuminates, the number of backtack stitches (0 - 9) in the A, B, C and D columns of the display are sewn continuously. After the sewing machine sews a full cycle of stitches set by A, B, C and D, the thread is trimmed automatically (models with thread trimmer).

・ When this key is pressed so that the indicator illuminates, the thread wiper (-4[][] specifications)

operates. (Refer to “4-8. Using the thread wiper (models with thread trimmer only)”.)

・ If the thread trimming lock has been set, the thread wiper key (6) will be disabled. (For details

on the thread trimming lock, refer to “8-4. Thread trimming lock (models with thread trimmer only)”.)

・ If thread trimming lock is set when the indicator of this key is illuminated, the indicator of the

thread wiper key (6) will switch off.

Power indicator

Refer to p.45

4197M

4198M

4199M 2138M 2139M

4161M

4162M

4163M

4174M

T-8421C, 8422C, 8452C, 8722C, 8752C

7. USING THE G10 OPERATION PANEL (BASIC OPERATIONS)

7-2. Sewing start and end backtack stitches

Setting start backtack stitches

Setting end backtack stitches

2911M

Start backtacking is carried out. After it has finished, normal sewing continues for as long as the treadle remains depressed.

NOTE:

If the treadle is returned to the neutral position, the sewing machine will continue operating until the set number of start backtack stitches has been sewn.

End backtacking is carried out. After it has finished, the thread is trimmed automatically (models with thread trimmer) and the sewing machine stops in the needle up position.

NOTE:

・ If the treadle is depressed backward before sewing of the set number of start backtack

stitches is complete, end backtacking will not be carried out.

・ If thread trimming lock is set, the sewing machine will stop in the needle up position

without thread trimming being carried out.

For example, 3 stitches and 4 stitches

4200M

Example:

4201M

2159M

2160M

T-8421C, 8422C, 8452C, 8722C, 8752C

7. USING THE G10 OPERATION PANEL (BASIC OPERATIONS)

7-3. Sewing continuous backtack stitches

Setting continuous backtack stitches

2185B

NOTE:

・ If the treadle is returned to the neutral position while continuous backtacking is being

carried out, the sewing machine will stop at the point where the treadle returns to the neutral position.If the treadle is depressed again, operation will resume from the point where it was interrupted.

・ If thread trimming lock is set, the sewing machine will stop in the needle up position

without thread trimming being carried out.

Example:

4202M

2159M

T-8421C, 8422C, 8452C, 8722C, 8752C

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

The operations described in this section should only be carried out by a technician.

8-1. Changing the needle stop position

This sets whether the needle bar stops in the needle up stop position or the needle down stop position when the treadle is returned to the neutral position and sewing stops.

* This setting cannot be carried out if the lock function is on. (For details on turning the lock function off, refer to “8-7.

Lock function”.)

Activating setting mode

(While pressing the end backtack key, press the power ON switch.)

Setting the needle up stop and needle down stop positions

(Setting value)

(Setting item)

・ When the key is pressed, the “UP”

・ When the key is pressed, the “dn”

… Needle up stop

… Needle down stop

NOTE:

The setting will be stored and the display will return to the setting item.

(Setting item)

4203M

display will appear.

If the start backtack key (1) is pressed once more, the start backtack indicator will switch off and the display will return to the setting item.

4204M

Setting mode will be exited and normal operation will be possible.

T-8421C, 8422C, 8452C, 8722C, 8752C

4205M

4206M

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

8-2. Slow start

When the slow start setting is enabled, the two stitches at the sewing start after thread trimming will be sewn at 700 sti/min. After this, the sewing speed corresponds to the treadle depression amount.

* This setting cannot be carried out if the lock function is on. (For details on turning the lock function off, refer to “8-7.

Lock function”.)

Activating setting mode

(While pressing the end backtack key, press the power ON switch.)

Selecting “SloW” (slow start)

Enabling and disabling slow start

(Press twice)

4203M

4207M

4208M 2138M 2139M

(Setting item)

(Setting value)

(Setting item)

・ When the key is pressed, the “on”

display will appear.

・ When the key is pressed, the “oFF”

display will appear.

Slow start enabled

…

… Slow start disabled

NOTE:

If the start backtack key (1) is pressed once more, the start backtack indicator will switch off and the display will return to the setting item.

The setting will be stored and the display will return to the setting item.

Setting mode will be exited and normal operation will be possible.

T-8421C, 8422C, 8452C, 8722C, 8752C

4209M

4206M

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

8-3. Correction sewing

When correction sewing is enabled, sewing will be carried out at slow speed (250 sti/min) while the actuator switch is being pressed when the sewing machine is stopped.

* This setting cannot be carried out if the lock function is on. (For details on turning the lock function off, refer to “8-7.

Lock function”.)

Activating setting mode

(While pressing the end backtack key, press the power ON switch.)

Selecting “Corr” (correction sewing)

Enabling and disabling correction sewing

(Press once)

4203M

4210M

4208M 2138M 2139M

(Setting item)

(Setting value)

(Setting item)

・ When the key is pressed, the “on”

display will appear.

・ When the key is pressed, the “oFF”

display will appear.

Correction sewing enabled

…

… Correction sewing disabled

NOTE:

If the start backtack key (1) is pressed once more, the start backtack indicator will switch off and the display will return to the setting item.

The setting will be stored and the display will return to the setting item.

Setting mode will be exited and normal operation will be possible.

T-8421C, 8422C, 8452C, 8722C, 8752C

4211M

4206M

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

8-4. Thread trimming lock (models with thread trimmer only)

Thread trimming not locked Thread trimming locked

* This setting cannot be carried out if the lock function is on. (For details on turning the lock function off, refer to “8-7.

Lock function”.)

Activating setting mode

(While pressing the end backtack key, press the power ON switch.)

Selecting “trdi” (thread trimming lock)

(Press three times)

Enabling and disabling thread trimming lock

Thread trimming is carried out.

(Setting item)

(Setting value)

2189B

(Setting item)

Thread trimming is not carried out.

(Setting item)

・ When the key is pressed, the “on”

display will appear.

・ When the key is pressed, the “oFF”

display will appear.

Thread trimming locked

…

Thread trimming not locked

…

NOTE:

If the start backtack key (1) is pressed once more, the start backtack indicator will switch off and the display will return to the setting item.

The setting will be stored and the display will return to the setting item.

4208M 2138M 2139M

2190B

4212M

4213M

Setting mode will be exited and normal operation will be possible.

T-8421C, 8422C, 8452C, 8722C, 8752C

4206M

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

8-5. Setting the maximum sewing speed

・ The maximum sewing speed can be set to a speed from 250 sti/min up to the maximum sewing speed which is set for the

head detector unit.

・ If the treadle is depressed as far as it will go, sewing will be carried out at the maximum sewing speed which is set here.

* This setting cannot be carried out if the lock function is on. (For details on turning the lock function off, refer to “8-7.

Lock function”.)

Setting the maximum sewing speed

NOTE:

While the indicator of the MAX key is illuminated, all keys other than the keys for the A and B columns will be disabled. If the MAX key is pressed once more, the indicator of the MAX key will switch off and normal key operations can then be carried out.

(Current setting value)

2191B

The maximum sewing speed is set in columns A and B. (Setting can be carried out in units of 100 sti/min.)

・ When the key is pressed, the setting increases.

Example:

・ When the key is pressed, the setting decreases.

2192B 2138M 2139M

The display will return to what was shown before the MAX key was pressed.

4216M

T-8421C, 8422C, 8452C, 8722C, 8752C

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

8-6. Adjusting the needle up stop position

(While pressing the key (1), press the power ON switch.)

Selecting “UPoS”

(Press once)

Needle up stop position setting

(Setting value)

(Setting item)

Example:

Becomes higher

Becomes lower

(Setting item)

* For details on other adjustment items, refer to the Service Manual.

4217M 2138M

“MorG” will appear in the display (2).

2193B

・ If you press the key, the setting value will

increase and the needle up stop position will become lower.

・ If you press the key, the setting value will

decrease and the needle up stop position will become higher.

・ The setting range is from –5 to 10.

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

rotation of approximately 10° for the upper shaft.

2194B 2138M 2139M

The setting will be stored and the display will return to the setting item.

4220M

Normal sewing machine operation will then be possible.

4206M

T-8421C, 8422C, 8452C, 8722C, 8752C

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

8-7. Lock function

DANGER

When the lock function is set to “ON”, the key operations for

Control box

4221M

making settings such as the following will be disabled in order to prevent these settings from being accidentally changed.

(Examples of disabled key operations)

・ MAX key

・ Initialization ………………… etc.

< To turn on the lock function >

Set DIP switch 1 to ON.

< To turn off the lock function >

Set DIP switch 1 to OFF. (The lock will be canceled and the functions can then be set.)

8-8. Resetting all settings to their defaults

* This setting cannot be carried out if the lock function is on. (For details on turning the lock function off, refer to “8-7.

Lock function”.)

Activating initialization mode

(While pressing the continuous backtack key, press the power ON switch.)

(Press for 2 seconds or more)

“in.AL” will appear in the display (1).

Once initialization is complete, the “in.AL” appearing in the display (1) will disappear and normal sewing machine operation will then be possible.

4222M

4206M

T-8421C, 8422C, 8452C, 8722C, 8752C

9. SEWING

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

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

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.

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

9-1. Sewing

Lower thread

CAUTION

Lower thread

2471B

2472B

2114M

2182B

9. SEWING

1. While holding the two upper threads with your fingers, turn the machine pulley by hand toward you until the lower threads come out onto the feed dog.

2. Pull the lower threads toward you and check that they pull out smoothly.

3. Press the ON power switch (1). The power indicator (2) will illuminate.

4. Use the operating panel to carry out the programming

which is necessary for sewing. (Refer to the chapter on “5./7. Using the operating panel”.)

5. Depress the treadle to start sewing.

T-8421C, 8422C, 8452C, 8722C, 8752C

9. SEWING

9-2. Backtacking

2916M

2917M

When the actuator switch (1) or the reverse lever (2) is pressed during sewing, the feed direction will be reversed. When it is released, the feed direction will return to normal.

< Actuator switch rotation function >

The actuator switch can be rotated 90 degrees as shown in the illustration. Select the position (A or B) that is easier to use.

2918M

T-8421C, 8422C, 8452C, 8722C, 8752C

9-3. Sewing condensed stitches

Sewing direction

Condensed stitches

Locked Unlocked

2195B

2920M

9. SEWING

y If you press the actuator switch (1) or the reverse lever (2)

while sewing is in progress, you can sew stitches (forward direction) with small stitch lengths.

y Before carrying out sewing, set the stitch length for

condensed stitches as follows.

1. Unlock the stitch length dial (4) by turning the dial lock

lever (3) to the right.

2. Turn the stitch length dial (4) to the stitch length to be

used for condensed stitches.

3. Loosen the screw (5) and lift up the stopper (6) until it

touches the reverse stitching lever plate (7).

4. Tighten the screw (5) to secure the stopper (6).

1. Return the stitch length dial (4) to the stitch length for normal sewing.

2. Turn the dial lock lever (3) firmly to the left to lock the stitch length dial (4).

3. Start sewing.

4. At the position where you would like to start sewing condensed stitches, press the actuator switch (1) or the reverse lever (2). (Condensed stitches are sewn while the actuator switch (1) or reverse lever (2) is being pressed.)

* To stop sewing condense stitches and return to using the

backtack function, lower the stopper (6) so that it does not touch the reverse stitching lever plate (7).

2921M

T-8421C, 8422C, 8452C, 8722C, 8752C

10. THREAD TENSION

10-1. Adjusting the thread tension

Good even stitches

Upper thread Lower thread

0572M

0573M

0574M

Upper thread tension too weak or lower thread tension too strong

Upper thread tension too strong or lower thread tension too weak

2473B

Increase the upper thread tension. Decrease the lower thread tension.

Decrease the upper thread tension. Increase the lower thread tension.

CAUTION

Turn off the power switch before adjusting the lower thread tension. The machine may operate if the treadle is depressed by mistake, which could result in injury.

Becomes weaker Becomes stronger

2923M

Becomes stronger

Becomes weaker

Becomes stronger

Becomes weaker

Turn the adjusting screw (1) to adjust.

After the lower thread tension has been adjusted, adjust the upper thread tension so that a good, even stitch is obtained.

1. Lower the presser foot.

2. Adjust by turning the tension nut (2).

Becomes stronger

2924M

T-8421C, 8422C, 8452C, 8722C, 8752C

10. THREAD TENSION

10-2. Adjusting the presser foot pressure

Correct stitches

Upper thread

0894M

0895M

Skipped stitches occur

Increase the pressure.

Uneven stitch length

0896M

0897M

Stitches are puckered

Decrease the pressure.

The presser foot pressure should be as weak as possible, but strong enough so that the material does not slip. (Refer to “Adjusting screw height” in the table below as a

Becomes stronger

Becomes weaker

guide to adjustment.)

1. Loosen the adjusting nut (1).

2. Turn the presser adjusting screw (2) to adjust the presser foot pressure.

3. Tighten the adjusting nut (1).

Reference values

Use Adjusting screw height

For foundation Approx. 34mm

For light-weight and

medium- weight

Approx. 34mm

materials

For heavy-weight

materials

Approx. 29mm

2925M

T-8421C, 8422C, 8452C, 8722C, 8752C

10. THREAD TENSION

10-3. Adjusting the presser foot floating amount (minute lifting amount)

3096M

Floating amount

Raise

Lower

3097M

• 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.

• In addition, this can be useful for increasing ease of working when sewing curves.

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.

< Guide to adjustment when sewing curves >

When the material is placed under the presser foot (1) and the feed dog (2) is moved to its lowest position and the material is moved, there should ideally be some resistance in the material.

If the floating amount is too small

• Ease of working (handling) will be poorer when sewing curves.

If the floating amount is too large

• The stitch lengths and seam lines will be unstable.

10-4. Adjusting the trailing length after thread trimming (models with

thread trimmer only)

y At the time of thread trimming, the thread tension is

loosened and tension is applied by the pretension (1) only.

y The normal trailing length for the upper thread is 35 mm. y If the tension of the pretension (1) is increased, the

lengths of the threads trailing from the needle tips will be reduced; if the tension is reduced, the lengths will be increased.

Adjust by turning the pretension (1).

Longer

35 mm or more

Shorter

Trailing thread

2258B2926M

T-8421C, 8422C, 8452C, 8722C, 8752C

10-5. Adjusting the thread take-up amount

Do not pass the

thread through.

Center

Pass the thread through.

Thread take-up amount is too large

Start of movement

2928M

2929M

3018M

Thread take-up amount is too small

3019M

The thread take-up amount is adjusted by how the thread is passed through the thread amount adjuster (1).

For all models except foundation specifications and T-8452C-405

Do not pass the thread through the thread amount adjuster (1). Loosen the screw (2) and slide the thread amount adjuster (1) to the right-side position.

For foundation specifications and T-8452C-405

Pass the thread through the thread amount adjuster (1). The standard position of the thread amount adjuster (1) is when the screw (2) is in the center of the adjustment range.

When the thread has been passed through the thread amount adjuster (1), the thread take-up amount becomes less when the thread amount adjuster (1) is moved to the right.

It is better not to pass the thread through the thread amount adjuster (1):

・ When sewing heavy materials using a sewing machine

with foundation specifications

・ When the thread take-up amount is not enough, such as

when the stitch length is increased

It is better to pass the thread through the thread amount adjuster (1):

・ When sewing with slippery threads such as synthetic

yarns

・ When sewing light materials ・ When sewing with a stitch length of 2 mm or less ・ When sewing under any of the above three conditions and

you would like to prevent skipped stitches, thread tightening problems such as looping, or thread breakages

< Guide to adjustment >

The standard thread take-up amount is when the thread tension spring (3) starts to move when the loop is moved to point (B) which is slightly in front of point (A) where the rotary hook tip catches the upper thread loop and the rotary hook thread amount is at its maximum.

• If the thread take-up amount is too large, the thread tension spring (3) will not start to move even after point (A) is passed.

….. This can cause skipped stitches, poor thread tightening and thread breakages.

• If the thread take-up amount is too small, the thread take-up spring (3) will start moving before point (B).

….. This can cause thread breakages, overtightening of the upper thread and pulling of the seam.

The thread take-up amount required will vary depending on the type of thread, the thickness of the material and the stitch length, so adjust the thread take-up amount to suit the sewing conditions.

10. THREAD TENSION

T-8421C, 8422C, 8452C, 8722C, 8752C

11. CLEANING

CAUTION

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.

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

11-1. Daily cleaning procedures

The following cleaning operations should be carried out each day in order to maintain the performance of this machine and to ensure a long service life. Furthermore, if the sewing machine has not been used for a long period of time, carry out the following cleaning procedures before using it again.

1. Turn the machine pulley to move the needle to the needle up stop position.

2. Open the slide plates at the left and right.

3. Remove the bobbin.

4. Clean the thread scraps from the rotary hook.

5. Install the bobbin (and the bobbin case).

2475B

Use only the lubricating oil <NIPPON OIL CORPORATION Sewing Lube 10N; VG10> specified by Brother.

* If this type of lubricating oil is difficult to obtain, the recommended

oil to use is <Exxon Mobil Essotex SM10; VG10>.

1. If the lubricating oil level drops below the bottom reference line (2) of the oil gauge window (1), be sure to add more oil. (Refer to p.9.)

2357B

T-8421C, 8422C, 8452C, 8722C, 8752C

1. Replace the needle if it is bent or if the tip is broken.

2. Check that the upper threads have been threaded correctly. (Refer to page 24.)

3. Carry out a test sewing.

2196B

1. If the oiler (1) has filled with oil, unscrew the oiler (1) and dispose of the oil inside it.

2. Screw the oiler (1) back into the oil pan.

3002M

11-2. Lubricating via the oil cover (every 6 months)

Pour lubricating oil into the oil cover (1) about once every six months.

11. CLEANING

Pour lubricating oil into the oil cover (1) about as often as grease is applied.

2190M

2358B

Use only the lubricating oil <NIPPON OIL CORPORATION Sewing Lube 10N; VG10> specified by Brother.

* If this type of lubricating oil is difficult to obtain, the recommended

oil to use is <Exxon Mobil Essotex SM10; VG10>.

1. Tilt back the machine head.

2. Pour lubricating oil into the oil cover (1) until the oil level reaches the reference line (2). (Refer to p.9.)

3. Return the machine head to its normal position.

T-8421C, 8422C, 8452C, 8722C, 8752C

11. CLEANING

11-3. Applying grease (Semi dry specifications)

[When “GrUP” appears ... When using the G50 operation panel]

If “GrUP” flashes in the display (1) and the buzzer sounds when the power ON switch is pressed, it means that it is time to add grease. (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 display (1) will change to stitch number display mode and sewing will be possible when the treadle is depressed.

NOTE

・ If you do not apply grease when the “GrEASEUP” notification flashes, the notification will continue to 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), “ E100” 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.

2199B

3704M

T-8421C, 8422C, 8452C, 8722C, 8752C

Use Brother-specified “Grease unit (SA8837-001)”.

1. Using the tube

2. Applying grease

Follow the procedure below to apply grease to the places indicated by arrows on the next page.

Insert the tip of the nozzle (1) all the way into the hole in the part.

1. Turn the power switch to “OFF”.

2. Remove the screw (2). (Refer to the next page for greasing locations.)

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

4. Tighten the screw (2) to push in the grease.

Apply grease without letting it spill out.

5. Use a cloth to wipe away any excess grease from around the screw

6. Apply grease to all locations shown on the next page in the same way.

7. Carry out the reset procedure given on the next page.

NOTE:

・ Once the grease tube has been opened, remove the nozzle from the

・ The grease should be used as quickly as possible.

・ When using the grease again, remove any old grease from inside the

(Store the tube away carefully once the tube has been opened, otherwise the grease remaining inside the tube may deteriorate, and this may affect its lubricating performance.)

2937M

Grease

Tighten the screw (2) to push in the grease.

(2).

tube, attach the cap securely and store the tube in a cool dark place.

nozzle first.

11. CLEANING

4087M

2936M

T-8421C, 8422C, 8452C, 8722C, 8752C

11. CLEANING

Turn the machine pulley until the screw (1) can be seen.

Use the tip of a screwdriver or similar to apply 5-10 mm beads of grease to the slide block slider (2).

2201B

4 places at top, bottom, left and right of the slide block (3)

* Pour oil into the oil cover at the same time. (Refer to p.9.)

2202B

Resetting the grease consumption amount >

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

1. While pressing the key (1) and the key (2) at the right end simultaneously, press the power ON switch.

2. “GuCt xxx” will appear in the display (3). (“xxx” represents the amount of grease consumed. For example, “100” means that 100% of the grease has been consumed.)

3. Press the RESET key (4).

4. The display (3) will change to “GuCt 0”.

5. Press the FUNC key (5). The display (3) will change to stitch number display mode and treadle operation will be possible.

(This completes the reset procedure.)

2259B

T-8421C, 8422C, 8452C, 8722C, 8752C

11. CLEANING

11-4. Applying grease (Semi dry specifications)

[When “GrUP” appears ... When using the G10 operation panel]

1. Press the thread wiper key (2).

2. The display (1) will change to stitch number display mode and sewing will be possible when the treadle is depressed.

NOTE

・ If you do not apply grease when the “GrUP” notification flashes, the notification will continue to 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 “GrUP” notification appears without applying grease (or without

carrying out the reset procedure), “E100” 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.

2260B

3704M

T-8421C, 8422C, 8452C, 8722C, 8752C

11. CLEANING

Use Brother-specified “Grease unit (SA8837-001)”.

1. Using the tube

2. Applying grease

Follow the procedure below to apply grease to the places indicated by arrows on the next page.

Insert the tip of the nozzle (1) all the way into the hole in the part.

1. Turn the power switch to “OFF”.

2. Remove the screw (2). (Refer to the next page for greasing locations.)

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

4. Tighten the screw (2) to push in the grease.

Apply grease without letting it spill out.

5. Use a cloth to wipe away any excess grease from around the screw

6. Apply grease to all locations shown on the next page in the same

7. Carry out the reset procedure given on the next page.

NOTE:

・ Once the grease tube has been opened, remove the nozzle from the

・ The grease should be used as quickly as possible.

・ When using the grease again, remove any old grease from inside the

(Store the tube away carefully once the tube has been opened, otherwise the grease remaining inside the tube may deteriorate, and this may affect its lubricating performance.)

2937M

Grease

Tighten the screw (2) to push in the grease.

(2).

way.

tube, attach the cap securely and store the tube in a cool dark place.

nozzle first.

4087M

2936M

T-8421C, 8422C, 8452C, 8722C, 8752C

* Pour oil into the oil cover at the same time. (Refer to p.9.)

11. CLEANING

2201B

Turn the machine pulley until the screw (1) can be seen.

Use the tip of a screwdriver or similar to apply 5-10 mm beads of grease to the slide block slider (2).

4 places at top, bottom, left and right of the slide block (3)

2202B

Resetting the grease consumption amount >

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

1. While pressing the key (1) and the key (2) at the right end simultaneously, press the power ON switch.

2. “GuCt” will appear in the display (3).

3. Press the end backtack key (4).

4. The indicator of the end backtack key (4) will illuminate and the display (3) will change to showing “xxx”. (“xxx” represents the amount of grease consumed. For example, “100” means that 100% of the grease has been consumed.)

5. Press the continuous backtack key (5) for 2 seconds or more.

6. The display (1) will change to “ 0”.

7. Press the thread wiper key (6). The display (3) will change to stitch number display mode and treadle operation will be possible. (This completes the reset procedure.)

2261B

T-8421C, 8422C, 8452C, 8722C, 8752C

2138M 2139M

12. ADJUSTING THE ROTARY HOOK LUBRICATION AMOUNT

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.

More oil Less oil

Spattered oil

Too much Correct Too little

2941M

2942M

2476B

1. Tilt back the machine head.

2. Turn the oil adjusting screw (1) to adjust the height to within 10-15 mm.

1. Turn off the power switch.

2. Remove the thread from all points from the thread take-up

to the needle.

3. Remove the needle and the bobbin.

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

5. Turn on the power switch.

6. 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).

7. Place the lubrication amount check sheet (2) to the left of

the rotary hook (the right side is the right side of the rotary hook), and hold it in place while running the sewing machine at the normal sewing speed for approximately 8 seconds. (Any type of paper can be used as the lubrication amount check sheet (2).)

8. Check the amount of oil which has spattered onto the

sheet.

1. Tilt back the machine head.

2. Turn the adjusting screw (1) to adjust the lubrication

amount.

・ If the rotary hook adjusting screw (1) is turned

counterclockwise, the lubrication amount becomes greater.

・ If the rotary hook adjusting screw (1) is turned

clockwise, 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 (1) 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.

T-8421C, 8422C, 8452C, 8722C, 8752C

13. STANDARD ADJUSTMENT

CAUTION

13. STANDARD ADJUSTMENT

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.

Secure the table so that it will not move when tilting back the machine head. If the table moves, it may crush your feet or cause other injuries.

13-1. Safety switch position

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

Machine bed

Table

・ When carrying out inspection, adjustment and

The standard installation position for the safety switch (1) is shown in the illustration at left. At the time of shipment from the factory, dimension (A) is adjusted to 3 mm, and normally this does not need to be readjusted. However, if the dimensions of the work table make it so that the gap between the machine bed and the table hole is wider or narrower than the standard gap (1.5 mm), it may have an adverse effect on the operation of the safety switch (1). If this happens, adjust as follows.

* If the operation of the safety switch (1) is affected in this

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.

way, the sewing machine will not start when the treadle is depressed.

< Adjustment method >

1. Loosen the screw (2).

2. Move the safety switch (1) to the left or right to adjust its position so that the gap (B) between the safety switch (1) and the table is 4.5 mm.

3. Tighten the screw (2).

3013M

T-8421C, 8422C, 8452C, 8722C, 8752C

13. STANDARD ADJUSTMENT

13-2. Thread take-up amount for thread take-up spring

< Measurement method >

3014M

Pass upper thread through thread take-up

3015M

35mm or more

Pull

The standard thread take-up length for thread take-up springs R (1) and L (2) is 7 mm. You can adjust the thread take-up amounts by changing the heights of the stopper [right] (3) and the stopper [left] (4).

* The standard heights of the stopper [right] (3) and the

stopper [left] (4) are when the are aligned with the tension stud (5).

< Adjustment method >

The thread take-up amount for a thread take-up spring decreases when the height of the stopper is increased.

Height of stopper [right] (3) [for right thread]

1. Loosen the screw (6), and then slide the stopper [right] (3) to adjust the thread take-up amount.

2. Tighten the screw (6).

Height of stopper [left] (4) [for left thread]

1. Loosen the screw (7), and then slide the stopper [left] (4) to adjust the thread take-up amount.

2. Tighten the screw (7).

NOTE:

If using a thread trimming sewing machine, the trailing length for the left upper thread may become shorter after thread trimming because of the twist in the thread. The trailing length is normal if the upper thread length is 35 mm when the thread is pulled from the needle hole. If the thread length is shorter than this, reduce the thread take-up amount of the thread take-up spring. However, if using fine threads (such as #50 polyester thread or finer), reducing the thread take-up amount too much may cause the right upper thread to be cut too short, or it might result in thread trimming errors for the left upper thread.

Trailing thread

3016M

T-8421C, 8422C, 8452C, 8722C, 8752C

13-3. Thread take-up spring tension

< Measurement method >

Do not pass thread through thread take-up

Upper limit position when measuring thread take-up amount

Stronger

Weaker

Stronger

3017M

13. STANDARD ADJUSTMENT

The standard tensions for the thread take-up spring R (1) and thread take-up spring L (2) are as follows depending on sewing machine specifications.

For foundation (-T[]F) 0.25N For light-weight and medium-weight materials

0.34N (-[][]3) For heavy-weight materials (-405,-407) 0.70N

< Adjustment method >

Thread take-up spring R (1) [for right thread]

1. Loosen the set screw (3), and turn the adjusting thumb (4) to adjust the tension.

2. Tighten the set screw (3).

Thread take-up spring L (2) [for left thread]

1. Loosen the tension nut (5).

2. Use a small screwdriver to turn the tension stud (6) to adjust the tension.

3. Tighten the tension nut (5).

T-8421C, 8422C, 8452C, 8722C, 8752C

13. STANDARD ADJUSTMENT

13-4. Clearance between r otary hook and needle plate

The clearance (A) between the rotary hook (1) and the needle plate (2) is adjusted as follows at the time of shipment from the factory.

Model Distance (A)

Without thread trimming

T-8421C

With thread trimming

T-8422C T-8722C T-8452C T-8752C

3054M

3055M

Touching gently

3056M

• Check clearance (A) each time parts such as the rotary hook (1) and the needle plate (2) that affect clearance (A) are replaced.

• To adjust clearance (A), replace the thrust ring (4) that is in between the rotary hook (1) and the rotary hook base (3).

• Three types of thrust ring (4) are available. Measure the thickness of the thrust ring (4) that is currently being used, and replace it with a thrust ring (4) of the appropriate width.

Part code Thickness SA4444-001 0.8 mm SA4038-001 1.0 mm S09260-001 1.2 mm

• When replacing the rotary hook (1), loosen the three set screws (5). Be careful not to lose the thrust ring (4) at this time.

NOTE:

There is a piece of felt (7) for lubrication at the base of the rotary hook shaft (6). Gently press down on the rotary hook (1) when tightening the set screws (5) so that the rotary hook (1) does not lift up.

If the clearance is too large

• The inner rotary hook may come out from the needle plate (2).

If the clearance is too small

• Poor thread tightening may occur.

• Lower thread trimming errors may occur (models with thread trimmer).

• The right upper thread may be cut too short (models with thread trimmer).

* These problems may occur particularly if the stitch

length is large or when carrying out thread trimming during chaining-off.

0.9 – 1.2 mm

1.4 – 1.7 mm

T-8421C, 8422C, 8452C, 8722C, 8752C

13-5. Clearance between r otary hook and opener

1. Loosen the set screw (3) and move the opener (1) to the left or right to adjust so that the clearance between the rotary hook (2) and the opener (1) is 0.1–0.3 mm when the opener (1) is pulled as far as it will go in the direction of the arrow.

2. Tighten the set screw (3).

NOTE: If the clearance is too large

• Upper thread trimming errors may occur (models with thread trimmer).

• The right upper thread may be cut too short (models with thread trimmer).

If the clearance is too small

• The rotary hook may become damaged.

• The opener (1) may become damaged.

2477B

13. STANDARD ADJUSTMENT

13-6. Presser f oot height

Approx. 7mm

2206B

3059M

1. Remove the rear cover (1) and remove the rubber cap (2).

2. Loosen the nut (3) and loosen the presser adjusting screw (4).

3. Use the lifting lever (5) to raise the presser foot (6).

4. Loosen the screw (7) and move the presser bar (8) up or down to adjust so that the presser foot (6) is approximately 7 mm above the top of the needle plate.

NOTE:

Do not turn the presser bar (8) at this time.

5. Tighten the screw (7).

6. Turn the presser adjusting screw (4) to adjust the presser foot pressure, and then tighten the nut (3).

T-8421C, 8422C, 8452C, 8722C, 8752C

13. STANDARD ADJUSTMENT

13-7. Nee dle and rotary hook timing

Needle bar lowest position

Lower feed Needle feed

2203B

3040M

1. Set the stitch length dial to the actual length of the stitches to be sewn.

Standard stitch length

Specifications Stitch length dial

-T[]F 2

-[][]3 2

-405, -407 3

2. Remove the rubber cap (1).

3. Loosen the screw (5) and move the needle bar (2) up or down to adjust so that the top reference line (3) on the needle bar (2) is aligned with the bottom edge of the needle bar bracket (4) when the needle bar (2) is at its lowest position. (Be careful not to turn the needle bar (2) at this time.)

4. Securely tighten the screw (5).

5. At this time, the gaps (A) and (B) between the needle (6) and the front of the feed dog (7) should be about the same as each other.

6. Turn the machine pulley forward to raise the needle bar (2) until the reference line ((8) or (9), depending on the feed condition) on the needle bar (2) is aligned with the bottom edge of the needle bar base (4).

7. In this condition, secure the machine pulley with tape or similar, so that the needle bar (2) will not move.

The procedure up to this point determines the needle bar lift amount.

NOTE: If the needle bar lift amount is too large

• It will cause poor tightening in the right thread.

• Both the left and right seams will become uneven, and skipped stitches or thread breakages will occur.

• Upper thread trimming errors may occur, or the upper thread may be cut too short (models with thread trimmer).

• The upper thread trailing length will be too long (models with thread trimmer).

If the needle bar lift amount is too small

• Skipped stitches and thread breakages will occur.

• The upper thread trailing length will be too short (models with thread trimmer).

T-8421C, 8422C, 8452C, 8722C, 8752C

3041M

8. Loosen the screws (10), and then remove rotary hook base cover FL (11) and FR (12).

13. STANDARD ADJUSTMENT

(The screws (10) is designed so that they cannot be removed from the rotary hook base cover FL (11) and FR (12) to prevent them from being lost.)

9. Loosen the set screws (13) (three each at left and right). (However, be careful not to loosen them too much, otherwise the set screws (13) will touch the inside surface of the rotary hook base and the pinion gear (14) will not be able to turn. Loosen the set screws by the minimum amount which will still allow the rotary hook to move freely.)

10. Turn the rotary hook by hand to align the rotary hook tip

(15) with the middle of the needle. (Do not turn the machine pulley at this time.)

11. Tighten the set screws (13).

(Tighten the three set screws (13) a little bit at a time in order so that the pinion gear (14) does not become tilted.)

12. Remove the tape that is securing the machine pulley.

3042M

13. Use an oil-based marker pen to color in the hollow of the

needle.

14. With the needle raised, turn the machine pulley forward

while pushing the needle against the rotary hook tip (15)

Color in

with your finger to make a mark from the rotary hook tip (15) in the hollow of the needle.

15. Check that the distance (C) from the intersection

Mark

between the mark from the rotary hook tip (15) and the center line of the needle to the top edge of the needle hole is 1–1.5 mm. * If the distance is not 1–1.5 mm, loosen the screw (5)

again and adjust the height of the needle bar.

* If dimension (C) has been adjusted, the highest

3043M

reference line (3) on the needle bar (2) may be by the bottom edge of the needle bar base (4) when

hidden

the needle bar is at its lowest position, but this is not a problem.

If using a thread such as polyester thread which does not easily form stable loops

* If problems such as skipped stitches or upper thread

breakages occur, set the above distance (C) to 0.7–1.2 mm to make it easier for the rotary hook tip (15) to catch the upper thread loop.

NOTE:

• When the stitch length is changed, distance (C) will also

Needle bar

lowest position

change, so re-check distance (C) at such times.

• During quick reverse operation, distance (C) for the left needle will become shorter, so do not set it to less than

0.7 mm, otherwise the rotary hook tip (15) may touch the

Mark

projection (D) and this could damage the rotary hook tip (15).

2262B

T-8421C, 8422C, 8452C, 8722C, 8752C

13. STANDARD ADJUSTMENT

Color in

Mark

Lower

Higher

Insert the needle clamp all the wa

into the needle bar.

Needle center

Lowest

osition

3043M

3185M

2205B

13. Use an oil-based marker pen to color in the hollow of the needle.

14. With the needle raised, turn the machine pulley forward while pushing the needle against the rotary hook tip (15) with your finger to make a mark from the rotary hook tip (15) in the hollow of the needle.

15. Check that the distance (C) from the intersection between the mark from the totary hook tip (15) and the center line of the needle to the top edge of the needle hole is 1-1.5 mm.

If using a thread such as polyester thread which does not easily form stable loops

* If problems such as skipped stitches or upper thread

breakages occur, set the above distance (C) to 0.7–0.8 mm to make it easier for the rotary hook tip (15) to catch the upper thread loop.

NOTE:

• When the stitch length is changed, distance (C) will also change, so re-check distance (C) at such times.

• During quick reverse operation, distance (C) for the left needle will become shorter, so do not set it to less than

0.7 mm, otherwise the rotary hook tip (15) may touch the projection (D) and this could damage the rotary hook tip (15).

16. Loosen the set screw (16) and then pull the needle bar clamp (17) downward to remove it.

17. Turn the screw (18) to adjust so that the distance from the upper edge of the needle hole to the rotary hook tip (15) is 1-1.5 mm.

18. After adjustment is completed, insert the needle bar clamp (17) into the hole of the needle bar (2) as far as it will go, and check that the distance is 1-1.5mm. Secure it by tightening the set screw (16).

13-8. Installing the feed dog

1. Install the feed dog (1) to the feed bar (2) with the two

screws (3).

2. Tighten the feed dog support set screw (4) so that the tip

of the set screw (4) touches the bottom of the feed dog (1).

Touch

T-8421C, 8422C, 8452C, 8722C, 8752C

3060M

3. Tighten the nut (5) to secure the set screw (4).

* The set screw (4) is not used for installing the feed dog at

an angle.

13-9. Fee d dog position

13. STANDARD ADJUSTMENT

Needle

Should not be touching at any points

3061M

3062M

< Forward-back position adjustment >

Carry out this adjustment if the needle and the needle hole in the feed dog are not positioned correctly even though the clearance between the needle bar and the presser bar (13.3–13.7 mm) is correct.

1. Loosen the two screws (1).

2. Turn the feed rocker base arm (3) to adjust so that the

needle drops into the middle of the needle hole in the feed dog (2). (The needle will actually be slightly to the front when it goes into the feed dog (2), and will be slightly to the back when it comes out.)

3. Tighten the screw (1).

NOTE:

Do not overtighten the screw (1), otherwise it will damage the feed rocker base arm (3).

< Left-right position adjustment >

Adjust so that neither side of the feed dog touches the needle plate (4) when the needle plate (4) is secured to the bed with the screws (5) and (6). If the needle plate and the feed dog are touching, loosen the screw (1) and move the feed rocker base arm (3) sideways to adjust.

3063M

T-8421C, 8422C, 8452C, 8722C, 8752C

13. STANDARD ADJUSTMENT

13-10. Fee d dog height

3064M

3065M

Turn the machine pulley forward until the feed dog (1) is at its highest position, and then adjust so that the feed dog (1)protrudes 0.9–1.1 mm from the top of the needle plate (2).

1. Tilt back the machine head.

2. Loosen the screw (3) just enough so that the feed bar (4)

can slide.

3. Turn the height adjustment screw (5) as shown in the

illustration to adjust the height of the feed dog (1).

4. Securely tighten the screw (3).

5. Recheck the height of the feed dog (1).

NOTE: If the feed dog is too high

• The feed dog may touch the needle plate.

• The stitch length may become longer than the stitch length dial setting.

• Thread tightening may be poor when using thick threads.

• It may be difficult to obtain uniform stitch lengths for normal feed and reverse feed.

• Lower thread trimming errors may occur (models with thread trimmer).

If the feed dog is too low

• The stitch length may become shorter than the stitch length dial setting.

• It may be difficult to obtain uniform stitch lengths for normal feed and reverse feed.

• The feed dog may touch the movable knife (models with thread trimmer).

• Large variations in stitch length may occur at slow and fast sewing speeds.

Lower

Higher

3066M

T-8421C, 8422C, 8452C, 8722C, 8752C

13-11. Fee d dog angle

Front raised

Standard

Front lowered

13. STANDARD ADJUSTMENT

The standard angle for the feed dog is when the mark (2) on the feed bar shaft (1) is aligned with the reference line (4) on the feed rocker base arm (3).

1. Tilt back the machine head.

2. Loosen the set screw (5).

3. Insert a screwdriver into the slit (6) in the feed bar shaft (1), and turn it to make the adjustment.

4. Tighten the set screw (5).

* When the angle of the feed dog is adjusted, the

forward-back position of the feed dog will change. Loosen the two screws (7) and adjust the forward-back position of the feed dog in accordance with the needle (for lower feed, in accordance with the needle plate).

* In addition, when the angle of the feed dog is adjusted,

the height of the feed dog will also change, so readjust the height of the feed dog.

T-8421C, 8422C, 8452C, 8722C, 8752C

3067M

14. TROUBLESHOOTING

y Please check the following points before calling for repairs or service. y 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

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.

14-1. Sewing

Items with a “*” in the “Page” column should only be checked by a qualified technician.

Problem Possible cause Page

1 Upper thread is not tight.

Lower thread is not tight.

0573M 0574M

2 Loops appear in seam. y Is the thread path not smooth enough?

0977M

y Has the thread been threaded incorrectly?

If the thread is threaded incorrectly, thread it correctly.

y Is the upper thread tension or lower thread tension too weak?

Adjust the upper thread tension or lower thread tension.

y Is the thread take-up spring operating range too small?

Lower the position of the stopper.

If using a sewing machine with medium-weight material specifications, poor thread tightening may occur depending on the type of material being sewn. In such cases, replace the presser foot with one that has slots on the underside, or replace the feed dog with a grooved feed dog.

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

y 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.

y Is the thread take-up amount too large?

Adjust the thread take-up amount.

Slot

20-24

65*

Grooves

2944M

T-8421C, 8422C, 8452C, 8722C, 8752C

Problem Possible cause Page

Skipped stitches occur

while sewing

Skipped stitches at sewing

start

Thread unravelling at sewing start

2945M

2946M

14. TROUBLESHOOTING

y Is the needle tip bent? Is the needle tip blunt?

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

y Is the needle properly installed?

If it is incorrect, install the needle correctly.

y Is the machine properly threaded?

If it is incorrect, thread the thread correctly.

y Is the presser foot pressure too weak?

Adjust the presser foot pressure.

y Is the needle too thin?

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

y Is the presser foot too high?

Adjust the height of the presser foot.

y Is the thread take-up spring too weak?

Adjust the tension of the thread take-up spring.

y Is the thread take-up amount too large?

Adjust the thread take-up amount.

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

Reduce the tension of the thread take-up spring.

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

Raise the position of the stopper.

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

trimming?

Adjust the pretension.

y Are the threads not being trimmed cleanly?

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

y Is the needle too wide?

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

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

Use the slow start feature.

y Is the needle up stop position too high?

Adjust the needle up stop position.

y Is the lower thread pressed by the plate spring (1) after thread

trimming?

If the lower thread is not pressed by the plate spring (1), adjust the installation position of the movable knife (2).

Lower thread

2947M

y If sewing light or medium-weight materials, is a presser foot with

slots on the underside or grooved feed dog being used?

Use a presser foot without slots. Use a feed dog without grooves.

Slot

Grooves

2944M

20-24

68*

66*

65*

T-8421C, 8422C, 8452C, 8722C, 8752C

thread

14. TROUBLESHOOTING

Problem Possible cause Page

5 Uneven seam y Is the presser foot pressure too weak?

Adjust the presser foot pressure.

y Is the feed dog too low?

Adjust the feed dog height.

y Is the bobbin scratched?

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

2948M

6 Large degree of puckering

(excess tension)

y Is the upper thread tension too strong?

Make the upper thread tension as weak as possible.

y Is the lower thread tension too strong?

Make the lower thread tension as weak as possible.

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

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

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

Move the stopper to as high a position as possible.

y Is the presser foot pressure too strong?

Adjust the presser foot pressure.

y Is the sewing speed too fast?

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

y Is the thread take-up amount too small?

2949M

Adjust the thread take-up amount.

7 Material slippage y Is the presser foot pressure too strong?

Adjust the presser foot pressure.

2950M

8 Lower thread is tangled at

the sewing start.

Spinning of bobbin during thread trimming

y 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.

y Is there too much thread

Lower

wound onto the bobbin?

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

y Is

the anti-spin spring attached? (Models with thread trimmer)

Attach the anti-spin spring.

y Is the bobbin turning smoothly?

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

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

being used?

Use only bobbins which are specified by Brother.

2951M

2124M

73*

66*

65*

• 22

T-8421C, 8422C, 8452C, 8722C, 8752C

14. TROUBLESHOOTING

Problem Possible cause Page

9 Upper and lower threads

are breaking.

y Is the needle bent or is the needle tip broken?

Replace the needle if it is bent or broken.

y Is the needle properly installed?

If it is incorrect, install the needle correctly.

y Is the machine properly threaded?

If it is incorrect, thread the thread correctly.

y Is the oil tank filled with lubricating oil?

If the level of lubricating oil is below the bottom reference line, add more oil.

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

Adjust the upper thread or lower thread tension.

y Is the rotary hook blocked with dust or thread scraps?

Clean the rotary hook.

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

operating range is too small?

Adjust the position of the stopper.

y 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.

y Is the thread path damaged?

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

y Is the thread take-up amount correct?

0471M

Adjust the thread take-up amount.

10 Incorrect thread trimming y Is the movable knife damaged or bent?

Replace the movable knife

11 Broken needles y Is the material being pushed or pulled with excessive force during

sewing?

y Is the needle bent, is the needle tip broken, or is the needle hole

blocked?

Replace the needle.

y Does the needle drop into the center of the needle hole in the feed

dog?

Check the needle drop position. If the needle does not drop into the center of the needle hole in the feed dog, reinstall the feed dog. If the needle bar has rotated, rotate the needle bar to the correct position.

Caution

20-24

65*

0469M

12 Machine does not operate

when power is turned on and treadle is pressed.

y 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.

y Furthermore, we recommend we recommend that through

steps be taken to account for such needles to comply with product liability regulations.

y Is the power supply connector

disconnected from the control box?

Insert the connector securely.

T-8421C, 8422C, 8452C, 8722C, 8752C

2197B

• 15

14. TROUBLESHOOTING

Problem Possible cause Page

13 Machine does not operate

at high speed.

14 Machine stops during

sewing.

15 Nothing appears on the

operation panel display.

16 “GrEASEUP” flashes on

the operation panel when the power is turned on.

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

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

y Is the fixed stitch key turned on?

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

y 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.)

y Is the power supply connector

disconnected from the control box?

Insert the connector securely.

y Is operation panel connector

P7 inside the control box disconnected?

Insert the connector securely.

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

Apply grease.

2197B

4264M

• 15

12*

57*

T-8421C, 8422C, 8452C, 8722C, 8752C

14-2. 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.

・ Items with a “ * ” in the “Page” column should only be checked by a qualified technician. ・ For items with “ ** ” appearing in the “Page” column, ask the place of purchase for

advice.

< Connector and DIP switch layout diagram >

Main PCB

2198B

14. TROUBLESHOOTING

4266M

Error code Possible cause Page

E050

E051

E055

E065

E066

・ The machine head was detected as being tilted back when the treadle was

depressed.

Press the power OFF switch and then return the machine head to the upright position. (If tilting back the machine head to carry out any tasks, press the power OFF switch first.)

・ The machine head was detected as being tilted back during sewing.

Turn the power off and then back on again.

・ Was the power ON switch pressed while the machine head was still tilted back?

Press the power OFF switch and then return the machine head to the upright position.

・ Is the 14-pin machine connector inside the control box disconnected?

Press the power OFF switch, and then check that the 14-pin machine connector is connected to connector P13 on the main PCB.

・ Was the power ON switch pressed while an invalid key was being pressed on the

operation panel?

Press the power OFF switch and check that no operation panel keys are being pressed.

・ There is a malfunction of the operation panel.

Replace the operation panel.

・ Was the actuator switch being pressed when the power ON switch was pressed?

Press the power OFF switch and check that the actuator switch is not being pressed

・ There is a problem with the actuator switch.

Replace the actuator switch.

12*

T-8421C, 8422C, 8452C, 8722C, 8752C

14. TROUBLESHOOTING

Error code Possible cause Page

E090

Treadle connector is not connected.

・ Is the 4-pin treadle connector inside the control box disconnected?

Press the power OFF switch, and then check that the 4-pin treadle connector is connected to connector P14 on the main PCB. If there is a broken wire in the cord of the treadle connector, replace the treadle unit.

E091

E095

E111

E130

・ 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.

・ Was the power ON switch pressed while the treadle was still depressed?

Return the treadle to the neutral position. When the treadle neutral position is detected, the error will be cleared and normal operation will then be possible.

・ Is the power supply voltage too low?

Check the power supply voltage.

・ The sewing machine could not stop correctly at the needle up stop position after

thread trimming.

Remove any thread scraps that may be blocking the motor. Press the power OFF switch and then turn the machine pulley by hand and check that it turns easily. Check that there are no problems with the thread trimming mechanism.

The sewing machine or motor do not operate when the treadle is depressed. ・ Is the 4-pin motor connector inside the control box disconnected?

Press the power OFF switch and check the connection of the 4-pin motor connector.

・ Has the sewing machine locked up?

Press the power OFF switch and then turn the machine pulley by hand and check that it turns easily.

・ Problem with control box.

Replace the control box.

12*

E131

Problem with motor encoder signal.

E132

Problem with motor operation.

E140

Motor reverse operation.

・ Is the 10-pin resolver connector inside the control box disconnected?

Press the power OFF switch, and then check that the 10-pin resolver connector is connected to connector P6 on the main PCB.

・ Problem with motor or main PCB.

Replace the motor or the control box.

・ Problem with motor.

Replace the motor.

・ Problem with drive PCB.

Replace the control box.

・ Motor reverse operation was detected.

Replace the motor.

12*

T-8421C, 8422C, 8452C, 8722C, 8752C

Error code Possible cause Page

E150

Motor is overheating.

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

protection has activated.

After the temperature has dropped, press the power ON switch and operate the sewing machine as normal.

14. TROUBLESHOOTING

E151

Problem with motor overheating sensor.

E190

Motor timeout.

E191

Thread trimming solenoid timeout.

E410

Error communicating with operation panel.

E440

Error writing data to main PCB.

E441

Error reading data from main PCB.

E442

Problem with data on main PCB.

E450

・ Is the connector inside the motor disconnected?

Insert the connector securely.

・ Malfunction of motor overheating sensor

Replace the motor.

・ 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.

・ 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.

・ Is the 12-pin operation panel connector inside the control box disconnected?

Press the power OFF switch, and then check that the 12-pin operation panel connector is connected to connector P7 on the main PCB.

・ Problem with main PCB.

Replace the control box.

・ Problem with main PCB.

Replace the control box.

・ The data on the main PCB is corrupted. Corrupt data was initalized.

Turn the power off and then back on again.

・ Model selection could not be loaded from the head detector unit.

Check that the head detector unit specifications are correct.

12*

E451

Error writing data to head detector unit.

E452

Head detector unit connection error.

・ Problem with head detector unit.

Replace the head detector unit.

・ Is the 6-pin head detector unit connector inside the control box disconnected?

Press the power OFF switch, and then check that the 6-pin head detector unit connector is connected to connector P8 on the main PCB.

T-8421C, 8422C, 8452C, 8722C, 8752C

12*

14. TROUBLESHOOTING

Error code Possible cause Page

E701

Abnormally high power supply voltage.

E705

Abnormally low power supply voltage.

E710

Motor overcurrent.

E791

Solenoid overcurrent.

E901

・ Does the power supply voltage match the control box voltage specifications?

Check that the voltage matches.

・ Is the power supply voltage abnormally high?

Check the power supply voltage.

・ Problem with control box.

Replace the control box.

・ Is the power supply voltage abnormally low?

Check the power supply voltage.

・ Problem with control box.

Replace the control box.

・ Is the electrical equipment connector inside the control box disconnected?

Press the power OFF switch, and then check that the drive PCB connector is connected to connector P4 on the main PCB.

・ This is displayed if the machine pulley moves stiffly when it is turned by hand, or if

the sewing machine locks up and an abnormal current is flowing.

Press the power OFF switch, and then turn the machine pulley by hand and check that it turns easily.

・ This is displayed if there is some problem with the motor and an abnormal current is

flowing.

Replace the motor.

・ Problem with control box.

Replace the control box.

・ 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 main PCB.

Replace the control box.

・ DIP switch No. 4 inside the control box is set to ON.

Press the power OFF switch and set DIP switch No. 4 to OFF.

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.

T-8421C, 8422C, 8452C, 8722C, 8752C

15. 7-SEGMENT DISPLAY

4268M

T-8421C, 8422C, 8452C, 8722C, 8752C

INSTRUCTION MANUAL

This is the original instructions.

T-8421C, 8422C, 8452C, 8722C, 8752C

SB1410-001 E

2010.05. B (1)

Brother FD4-B272, KE-435B Owner's Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

SAFETY INSTRUCTIONS

CONTENTS

1. MACHINE SPECIFICATIONS

2. NAMES OF MAJOR PARTS

3. INSTALLATION

3-1. Table processing diagram

3-2. Installation

3-3. Lubrication

3-4. Connecting the cords

3-4-1. Opening the control box cover

3-4-2. Connecting the cords

3-5. Test operation (Operating the treadle)

3-6. Adjusting the treadle operation

4. PREPARATION BEFORE SEWING

4-1. Installing the needle

4-2. Removing the bobbin

4-3. Winding the lower thread

4-4. Installing the bobbin

4-5. Threading the upper thread

4-6. Adjusting the stitch length

4-7. Using the knee lifter

4-8. Using the thread wiper (models with thread trimmer only)

4-9. Corner sewing method (T-8452C, 8752C)

4-9-1. To stop the needle bars (right and left)

4-9-2. Number of stitches: quick-reference guide

5. USING THE G50 OPERATION PANEL (BASIC OPERATIONS)

5-1. Names and functions

5-2. Sewing start and end backtack stitches

5-3. Sewing continuous backtack stitches

5-4. Sewing fixed stitches

5-5. Sewing pleat presser stitches

5-6. Using the lower thread counter

6. USING THE G50 OPERATION PANEL (ADVANCED OPERATIONS)

6-1. Names and functions

6-2. Adjusting the needle up stop position

6-3. LOCK key

6-4. Resetting all settings to their defaults

7. USING THE G10 OPERATION PANEL (BASIC OPERATIONS)

7-1. Names and functions

7-2. Sewing start and end backtack stitches

7-3. Sewing continuous backtack stitches

8. USING THE G10 OPERATION PANEL (ADVANCED OPERATIONS)

8-1. Changing the needle stop position

8-2. Slow start

8-3. Correction sewing

8-4. Thread trimming lock (models with thread trimmer only)

8-5. Setting the maximum sewing speed

8-6. Adjusting the needle up stop position

8-7. Lock function

8-8. Resetting all settings to their defaults

9. SEWING

9-1. Sewing

9-2. Backtacking

9-3. Sewing condensed stitches

10. THREAD TENSION

10-1. Adjusting the thread tension

10-2. Adjusting the presser foot pressure

10-3. Adjusting the presser foot floating amount (minute lifting amount)

10-5. Adjusting the thread take-up amount

11. CLEANING

11-1. Daily cleaning procedures

11-2. Lubricating via the oil cover (every 6 months)

12. ADJUSTING THE ROTARY HOOK LUBRICATION AMOUNT

13. STANDARD ADJUSTMENT

13-1. Safety switch position

13-2. Thread take-up amount for thread take-up spring

13-3. Thread take-up spring tension

13-4. Clearance between r otary hook and needle plate

13-5. Clearance between r otary hook and opener

13-6. Presser f oot height

13-7. Nee dle and rotary hook timing

13-8. Installing the feed dog

13-9. Fee d dog position

13-10. Fee d dog height

13-11. Fee d dog angle

14. TROUBLESHOOTING