CONTENTS
1. NAMES OF MAJOR PARTS ..........................................1
2. MACHINE SPECIFICATIONS ..........................................3
3. OPTIONAL PARTS .......................................................... 5
4. WORK TABLE ................................................................. 7
5. MOTOR ........................................................................... 8
6. INSTALLATION ............................................................... 9
6-1. Installing the oil pan .......................................... 10
6-2. Installing the machine head ............................. 11
6-3. Installing the knee lifter assembly
(Except -903) ....................................................... 12
6-4. Installing the belt ...............................................14
6-5. Installing the bobbin winder ............................. 14
6-6. Installing the belt cover ..................................... 15
6-7. Installing the cotton stand ................................ 17
5-8. Ground Wire Connections................................. 18
6-9. Lubrication .......................................................... 19
6-10. Checking the machine pulley rotating
direction .............................................................. 20
7. PREPARATION BEFORE SEWING ...............................21
7-1. Installing the needle ........................................ 21
7-2. Removing the bobbin case ...............................22
7-3. Winding the lower thread .................................23
7-4. Installing the bobbin case .................................25
7-5. Threading the upper thread.............................. 26
7-6. Adjusting the stitch length ................................ 27
7-7. Using the thread wiper (-403, -903) .................27
7-8. Using the upper knife........................................ 28
8. SEWING ........................................................................29
8-1. Sewing ................................................................ 30
8-2. Backtacking ......................................................... 30
9. THREAD TENSION ....................................................... 31
9-1. Adjusting the thread tension ............................31
9-2. Adjusting the trailing length after thread
trimming (B772A) ............................................... 32
9-3. Adjusting the presser foot pressure ................ 32
10. CLEANING .....................................................................35
11. REPLACING THE FIXED KNIFE AND MOVABLE
KNIFE (B772A) ..............................................................38
12. STANDARD ADJUSTMENTS .......................................41
12-1. Adjusting the thread tension spring ................ 42
12-2. Adjusting arm thread guide R ..........................44
12-3. Adjusting the presser foot height .................... 45
12-4. Adjusting the feed dog height ......................... 46
12-5. Adjusting the feed dog angle ...........................47
12-6. Adjusting the needle bar height ....................... 48
12-7. Adjusting the needle and rotary hook
timing .................................................................. 49
12-8. Adjusting the needle and feed mechanism
timing .................................................................. 50
12-9. Adjusting the upper knife ................................. 51
12-10.Adjusting the synchronizer (B772A) .................53
12-11.Adjusting the upper shaft and rotary hook
lubrication amount ............................................. 55
13. CHANGING THE CUTTING WIDTH .............................56
14. GAUGE PARTS LIST ....................................................59
15. TROUBLESHOOTING ...................................................61
DB2-B771A, B772A (English)