Service Manual
Page 4
... (DB2-B774) 41 III Adjusting thread wiper 42 M Adjusting potentio-meter (B7740) 43 M Checking feed mechanism weight (B7740) 44 M Adjusting sensor position 45 M Adjusting the indication of the distance between needle hole and sensor (B7740) 46 REPLACEMENTS 47 M Replacing Solenoids 47 Replacing tension release wire 50 M Replacing bobbin tension spring 50 ID Replacing photo-cell and reflector (B7740) 51 M Replacing Synchronizers 53 OPTIONAL EQUIPMENT 54 M Thread wiper 54 M Presser foot lifting solenoid set 55 TROUBLESHOOTING GUIDE...
... (DB2-B774) 41 III Adjusting thread wiper 42 M Adjusting potentio-meter (B7740) 43 M Checking feed mechanism weight (B7740) 44 M Adjusting sensor position 45 M Adjusting the indication of the distance between needle hole and sensor (B7740) 46 REPLACEMENTS 47 M Replacing Solenoids 47 Replacing tension release wire 50 M Replacing bobbin tension spring 50 ID Replacing photo-cell and reflector (B7740) 51 M Replacing Synchronizers 53 OPTIONAL EQUIPMENT 54 M Thread wiper 54 M Presser foot lifting solenoid set 55 TROUBLESHOOTING GUIDE...
Service Manual
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... -426 1 -926 Use Medium material Gathering Sewing speed 4,500 spm Maximum Stitch length 5 mm Maximum upper feed amount 6mm 8mm Presser foot height Presser bar lifter Knee lifter Automatic presser bar lifter 13 mm Minimum 10 mm 8mm Feed dog height 0.8 mm Needle DB x 1 #11 Thread trimmer O Thread wiper O Quick back O Automatic presser bar lifter _-I 0.8 mm 8mm 6mm 13 mm 6mm #11 AssemblyS Assembly B Use a maximum feed amount of DB2-B774 with automatic thread trimmer are shown below. SPECIFICATIONS INDUSTRIES, DB2-B773-00q MADE IN...
... -426 1 -926 Use Medium material Gathering Sewing speed 4,500 spm Maximum Stitch length 5 mm Maximum upper feed amount 6mm 8mm Presser foot height Presser bar lifter Knee lifter Automatic presser bar lifter 13 mm Minimum 10 mm 8mm Feed dog height 0.8 mm Needle DB x 1 #11 Thread trimmer O Thread wiper O Quick back O Automatic presser bar lifter _-I 0.8 mm 8mm 6mm 13 mm 6mm #11 AssemblyS Assembly B Use a maximum feed amount of DB2-B774 with automatic thread trimmer are shown below. SPECIFICATIONS INDUSTRIES, DB2-B773-00q MADE IN...
Service Manual
Page 31
... through the sensor hole. To adjust the timing, turn the level feed eccentric wheel m and the feed lifting eccentric wheel ® by turning the machine pulley, align the rotary hook point with the needle plate's upper surface, the needle tip should be 2-4 mm above ). Make sure the gap between the bobbin case holder position bracket 0 and the rotary hook 4 is 0.5 mm. El Rotary hook mechanism Needle bar bushing Needle b r Reference line...
... through the sensor hole. To adjust the timing, turn the level feed eccentric wheel m and the feed lifting eccentric wheel ® by turning the machine pulley, align the rotary hook point with the needle plate's upper surface, the needle tip should be 2-4 mm above ). Make sure the gap between the bobbin case holder position bracket 0 and the rotary hook 4 is 0.5 mm. El Rotary hook mechanism Needle bar bushing Needle b r Reference line...
Service Manual
Page 40
... and down timing using the eccentric pin ® of the upper feed lifting rock arm 0, place the connecting stud 0 and the upper feed connecting lever into the outer hole, and tighten it with the screw 0 as thick material, remove e. the screw liD of the upper feed lifting rock crank assembly 0. -36- If you need a larger upper feed dog movement for sewing things such as shown in the direction opposite of the machine, then...
... and down timing using the eccentric pin ® of the upper feed lifting rock arm 0, place the connecting stud 0 and the upper feed connecting lever into the outer hole, and tighten it with the screw 0 as thick material, remove e. the screw liD of the upper feed lifting rock crank assembly 0. -36- If you need a larger upper feed dog movement for sewing things such as shown in the direction opposite of the machine, then...
Service Manual
Page 41
... presser bar O. Be sure to make the needle thread tension stronger when sewing with the reference line. [I] Adjusting presser foot brother O-\ Backward Reference line 0 O 0 6mm (I) Adjusting the clearance of the presser foot 1) The standard amount that the upper feed dog feeds the material securely. NOTE: The stronger the upper feed pressure, the more the upper feed efficiency increases. However, if the upper feed is too strong, the upper feed dog pushes up the presser bar lift 0. 4) Insert a 6mm gauge under the presser. 5) Remove...
... presser bar O. Be sure to make the needle thread tension stronger when sewing with the reference line. [I] Adjusting presser foot brother O-\ Backward Reference line 0 O 0 6mm (I) Adjusting the clearance of the presser foot 1) The standard amount that the upper feed dog feeds the material securely. NOTE: The stronger the upper feed pressure, the more the upper feed efficiency increases. However, if the upper feed is too strong, the upper feed dog pushes up the presser bar lift 0. 4) Insert a 6mm gauge under the presser. 5) Remove...
Service Manual
Page 44
... the upper tension regulator assembly. The standard tension of the thread take -up spring is suspended by the bobbin thread. After lowering the presser foot, adjust the needle thread tension by turning the screw 0. To adjust the tension, rotate the tension stud 0 using a screwdriver. -40- Excessive needle thread tension Proper tension Decrease Increase After thread trimming, adjust the thread leader to 35-40 mm by turning the nut 0. 6 -8 mm e. Adjust the bobbin thread tension by turning the spring adjusting screw so that the bobbin case does...
... the upper tension regulator assembly. The standard tension of the thread take -up spring is suspended by the bobbin thread. After lowering the presser foot, adjust the needle thread tension by turning the screw 0. To adjust the tension, rotate the tension stud 0 using a screwdriver. -40- Excessive needle thread tension Proper tension Decrease Increase After thread trimming, adjust the thread leader to 35-40 mm by turning the nut 0. 6 -8 mm e. Adjust the bobbin thread tension by turning the spring adjusting screw so that the bobbin case does...
Service Manual
Page 49
El Adjusting sensor position The photo-cell position needs to be adjusted when the reflector position is changed. 0 0 0 O e 0 O 0 1 SET SUET 2 06 PLY IMPIR 3 PROGRA 0EI El El
El Adjusting sensor position The photo-cell position needs to be adjusted when the reflector position is changed. 0 0 0 O e 0 O 0 1 SET SUET 2 06 PLY IMPIR 3 PROGRA 0EI El El
Service Manual
Page 51
... 0. ®, 7) Remove the thread trimmer solenoid ®by removing the two nuts 0. 8) Remove the solenoid lever the washer 0 and the cushion @ by loosening the screw 0. 9) Replace the thread trimmer solenoid (code: 502815-001). -47- Attachment is done in the reverse order of the nylon connector 12P. 2) Tilt the machine head until it stops. 3) Loosen the screw 0. Disconnect the cord from the cord holder @. 4) Remove the cord from pins 4 and...
... 0. ®, 7) Remove the thread trimmer solenoid ®by removing the two nuts 0. 8) Remove the solenoid lever the washer 0 and the cushion @ by loosening the screw 0. 9) Replace the thread trimmer solenoid (code: 502815-001). -47- Attachment is done in the reverse order of the nylon connector 12P. 2) Tilt the machine head until it stops. 3) Loosen the screw 0. Disconnect the cord from the cord holder @. 4) Remove the cord from pins 4 and...
Service Manual
Page 54
... assembly ®. 6) Remove stop ring E © from the bobbin case 0 using a screwdriver. 4) Replace the bobbin tension spring (code:503246- 001). -50- Fasten the screw ® . 5) Secure the tension release wire 0 with the tension release wire presser (upper) 0. Attachment 1) Attach the tension release link assembly ® to the tension release wire 0 with stop ring E O. 2) Thread the tension release wire 0. 3) Attach the tension release link assembly @ to the tension release plate ® with stop ring E ®. Fasten the screw 0. 6) Insert the tension...
... assembly ®. 6) Remove stop ring E © from the bobbin case 0 using a screwdriver. 4) Replace the bobbin tension spring (code:503246- 001). -50- Fasten the screw ® . 5) Secure the tension release wire 0 with the tension release wire presser (upper) 0. Attachment 1) Attach the tension release link assembly ® to the tension release wire 0 with stop ring E O. 2) Thread the tension release wire 0. 3) Attach the tension release link assembly @ to the tension release plate ® with stop ring E ®. Fasten the screw 0. 6) Insert the tension...
Service Manual
Page 56
... machine head until it stops. 7) Remove the reflector cord from the the cord holder 0. 8) Remove the reflector cord from the the cord bushing 0. 9) Remove the cord holder (lower) 0 by removing the two screws ®. 10) Remove the bobbin case holder position bracket @ by removing the screw 0. 11) Remove the reflector @ by removing the two screws 0. 12) Replace the reflector. NOTE: Do not extend the cover above the needle plate upper surface . 2. NOTE: After attaching the photo-cell and the reflector, adjust...
... machine head until it stops. 7) Remove the reflector cord from the the cord holder 0. 8) Remove the reflector cord from the the cord bushing 0. 9) Remove the cord holder (lower) 0 by removing the two screws ®. 10) Remove the bobbin case holder position bracket @ by removing the screw 0. 11) Remove the reflector @ by removing the two screws 0. 12) Replace the reflector. NOTE: Do not extend the cover above the needle plate upper surface . 2. NOTE: After attaching the photo-cell and the reflector, adjust...
Service Manual
Page 57
... screws @. (Make sure the synchronizer assembly 0 can be moved manually.) 3) Tighten the screw and washer 0 temporarily at the middle of the long hole in the synchronizer . 4) Place the machine pulley 0 on the machine pulley 0. 6) Connect the synchronizer plug with the screw stop of the upper shaft. El Replacing Synchronizers Remove the belt cover if it with the screws @. (Of these screws @, align the one which comes...
... screws @. (Make sure the synchronizer assembly 0 can be moved manually.) 3) Tighten the screw and washer 0 temporarily at the middle of the long hole in the synchronizer . 4) Place the machine pulley 0 on the machine pulley 0. 6) Connect the synchronizer plug with the screw stop of the upper shaft. El Replacing Synchronizers Remove the belt cover if it with the screws @. (Of these screws @, align the one which comes...
Service Manual
Page 58
... screws O. Attaching the thread wiper O e • e brother 0 0 0 0 4 0 em No 7 No8 1) Attach the thread wiper solenoid assembly 0 to the machine head with the screw 0. 2) Fasten the cord on the machine head using the cord holder 0 and the screw ®. 3) Connect the terminal pin (male) with pins 7 and 8 of thread wiper ® does not strike the upper feed dog, presser foot, needle, and any other part. 2) After adjustment, tighten the screw O . -54- OPTIONAL EQUIPMENT M Thread wiper The code of the thread wiper set...
... screws O. Attaching the thread wiper O e • e brother 0 0 0 0 4 0 em No 7 No8 1) Attach the thread wiper solenoid assembly 0 to the machine head with the screw 0. 2) Fasten the cord on the machine head using the cord holder 0 and the screw ®. 3) Connect the terminal pin (male) with pins 7 and 8 of thread wiper ® does not strike the upper feed dog, presser foot, needle, and any other part. 2) After adjustment, tighten the screw O . -54- OPTIONAL EQUIPMENT M Thread wiper The code of the thread wiper set...
Service Manual
Page 59
... E 9) Pinch the knee lifter lever spring 0 between the knee lifter lever 0 and the upper part of the nylon connector 6. 7) Remove the six screws 0, remove the rear cover ID. 8) Remove the stud screw O. 111 Presser foot lifting solenoid set Attaching the presser foot lifting solenoid set [subclass -003] 18 360 67 4 Knee switch mounting holes OL 0 30.7 30.2 124 Presser foot lifting solenoid mounting holes Fig.A Fig. Attach them to the oil pan @ with the...
... E 9) Pinch the knee lifter lever spring 0 between the knee lifter lever 0 and the upper part of the nylon connector 6. 7) Remove the six screws 0, remove the rear cover ID. 8) Remove the stud screw O. 111 Presser foot lifting solenoid set Attaching the presser foot lifting solenoid set [subclass -003] 18 360 67 4 Knee switch mounting holes OL 0 30.7 30.2 124 Presser foot lifting solenoid mounting holes Fig.A Fig. Attach them to the oil pan @ with the...
Service Manual
Page 63
... needle. Adjust thread take -up spring. Blunt needle tip, jammed eye. Adjust thread wiper. 42 Thread breakage Improper threading threading Rethread. Adjust oil supply. -59- Replace needle. Adjust needle to 31 rotary hook timing. Improper needle installation Excessive needle thread tension Excessive bobbin thread tension Loose needle thread Insufficient rotary hook lubrication Needle Needle facing, height Needle tension thread Bobbin thread tension Thread take - 40 up spring operation Oil supply Replace needle. TROUBLESHOOTING GUIDE III Machine head Problem Cause...
... needle. Adjust thread take -up spring. Blunt needle tip, jammed eye. Adjust thread wiper. 42 Thread breakage Improper threading threading Rethread. Adjust oil supply. -59- Replace needle. Adjust needle to 31 rotary hook timing. Improper needle installation Excessive needle thread tension Excessive bobbin thread tension Loose needle thread Insufficient rotary hook lubrication Needle Needle facing, height Needle tension thread Bobbin thread tension Thread take - 40 up spring operation Oil supply Replace needle. TROUBLESHOOTING GUIDE III Machine head Problem Cause...
Service Manual
Page 64
...count needle. Adjust presser bar height. Adjust needle to 31 rotary hook timing. Adjust pretension. 40 Replace bobbin presser spring. 50 Thread take-up 40 spring tension. Problem Cause Check Solution Page Thread breaks --I Burr in material. Tighten presser foot 31 adjustment screw. Adjust take -u spring tension -60- Improper threading Threading Rethread. won 't raise bobbin thread. Replace needle. Adjust needle to 31 rotary hook timing. Reattach needle. Skipped stitches Poor presser foot contact Presser bar pressure Presser bar height dNeedle bar...
...count needle. Adjust presser bar height. Adjust needle to 31 rotary hook timing. Adjust pretension. 40 Replace bobbin presser spring. 50 Thread take-up 40 spring tension. Problem Cause Check Solution Page Thread breaks --I Burr in material. Tighten presser foot 31 adjustment screw. Adjust take -u spring tension -60- Improper threading Threading Rethread. won 't raise bobbin thread. Replace needle. Adjust needle to 31 rotary hook timing. Reattach needle. Skipped stitches Poor presser foot contact Presser bar pressure Presser bar height dNeedle bar...
Service Manual
Page 65
...Last stitch skipped, needle thread not caught by thread cutter Movable and fixed knives do not overlap c. Increase bobbin 40 thread tension. Needle, bobbin threads not trimmed Worn, rough movable, fixed knife edges Movable knife does not move Improper needle attachment b. Decrease needle 40 thread tension. replace thread trimming solenoid. Bobbin thread does not tighten. Problem Cause Check Solution Page Needle thread does not tighten. Replace bobbin, rotary hook. Reattach needle. Adjust thread takep-up spring stroke Knives Increase needle thread tension. 40...
...Last stitch skipped, needle thread not caught by thread cutter Movable and fixed knives do not overlap c. Increase bobbin 40 thread tension. Needle, bobbin threads not trimmed Worn, rough movable, fixed knife edges Movable knife does not move Improper needle attachment b. Decrease needle 40 thread tension. replace thread trimming solenoid. Bobbin thread does not tighten. Problem Cause Check Solution Page Needle thread does not tighten. Replace bobbin, rotary hook. Reattach needle. Adjust thread takep-up spring stroke Knives Increase needle thread tension. 40...
Specifications
Page 1
DB2-B773 B774 DB2-B7740 B7741 Single Needle Adjustable Top and Bottom Feed Lock Stitcher Single Needle Adjustable Top and Bottom Feed Lock Stitcher with Thread Trimmer Single Needle Adjustable Top and Bottom Feed Lock Stitcher with Thread Trimmer and Ply Sensor Single Needle Adjustable Top and Bottom Feed Lock Stitcher with Thread Trimmer and Programmable Shirring Device Specifications Model Subclass Use Sewing speed Max. stitch length Feed method Height of presser foot Needle bar stroke Thread take-up stroke Height of feed dog Max. DB2-B773 ...
DB2-B773 B774 DB2-B7740 B7741 Single Needle Adjustable Top and Bottom Feed Lock Stitcher Single Needle Adjustable Top and Bottom Feed Lock Stitcher with Thread Trimmer Single Needle Adjustable Top and Bottom Feed Lock Stitcher with Thread Trimmer and Ply Sensor Single Needle Adjustable Top and Bottom Feed Lock Stitcher with Thread Trimmer and Programmable Shirring Device Specifications Model Subclass Use Sewing speed Max. stitch length Feed method Height of presser foot Needle bar stroke Thread take-up stroke Height of feed dog Max. DB2-B773 ...
Specifications
Page 8
... parts list For topstitching Gauge type A 183558-101 Presser foot assy 151277-201 Free presser foot Upper feed dog S13256-001 Exchange parts assy for thin and medium materials Needle plate 159288-201 AC1 183579-101 159447-201 Free presser foot Exchange parts assy for thin and medium materials [DB2−B773, B774, B7740, B7741] Feed dog Use 159301-001 Men's and lady's wear etc., stitching sleeve caps, basting under sleeves, seaming back center, joining shoulders, sewing...
... parts list For topstitching Gauge type A 183558-101 Presser foot assy 151277-201 Free presser foot Upper feed dog S13256-001 Exchange parts assy for thin and medium materials Needle plate 159288-201 AC1 183579-101 159447-201 Free presser foot Exchange parts assy for thin and medium materials [DB2−B773, B774, B7740, B7741] Feed dog Use 159301-001 Men's and lady's wear etc., stitching sleeve caps, basting under sleeves, seaming back center, joining shoulders, sewing...
Specifications
Page 13
...-shaped type teeth ED - Part name Gathering separator assy Separator Part code 183627-001 S13369-001 Part name Separator S3 assy Separator Part code 183214-401 159321-101 For rolled-hemming Gauge type Presser foot assy Upper feed dog Needle plate Feed dog Use E 183562-001 151290-101 S13259-001 159294-001 159304-001 Free presser foot Exchange parts assy for medium materials Parallel type teeth 2002.1 DB2−B773, B774, B7740, B7741 13/21 For gathering Gauge type Presser foot...
...-shaped type teeth ED - Part name Gathering separator assy Separator Part code 183627-001 S13369-001 Part name Separator S3 assy Separator Part code 183214-401 159321-101 For rolled-hemming Gauge type Presser foot assy Upper feed dog Needle plate Feed dog Use E 183562-001 151290-101 S13259-001 159294-001 159304-001 Free presser foot Exchange parts assy for medium materials Parallel type teeth 2002.1 DB2−B773, B774, B7740, B7741 13/21 For gathering Gauge type Presser foot...
Specifications
Page 15
... sewing zipper φ1.8 KR 183577-001 Exchange parts assy for medium materials Needle plate 159292-101 φ1.6 [DB2−B773, B774, B7740, B7741] Feed dog Use S15074-001 Oblique type teeth P1.15 Skirt etc. For sewing zipper (Exclusive right) Gauge type Presser foot assy GC 183625-101 S13777-001 Upper feed dog S13778-001 Fixed presser foot Cross-shaped type teeth Exchange parts assy for medium materials 156617-101 Fixed presser foot S13267-001 Cross-shaped type...
... sewing zipper φ1.8 KR 183577-001 Exchange parts assy for medium materials Needle plate 159292-101 φ1.6 [DB2−B773, B774, B7740, B7741] Feed dog Use S15074-001 Oblique type teeth P1.15 Skirt etc. For sewing zipper (Exclusive right) Gauge type Presser foot assy GC 183625-101 S13777-001 Upper feed dog S13778-001 Fixed presser foot Cross-shaped type teeth Exchange parts assy for medium materials 156617-101 Fixed presser foot S13267-001 Cross-shaped type...