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Summary of Contents for Brother LZ2-B850
- Page 1 LZ2 - B850, B850W SERVICE MANUAL LZ2 - B851 Please read this manual before making any adjustments. SINGLE NEEDLE ZIGZAG LOCK STITCHER...
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Page 2: Safety Instructions
As a result of research and improvements regarding this product, some details of this manual may not be the same as those for the product you purchased. If you have any questions regarding this product, please contact a Brother dealer. SAFETY INSTRUCTIONS 1. - Page 3 Furthermore, do not excessively bend the cords or secure them too firmly with staples, Contact your Brother dealer or a qualified electrician otherwise there is the danger that fire or electric shocks for any electrical work that may need to be done.
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Page 4: Maintenance And Inspection
Turn off the power switch at the following times, smells are noticed, immediately turn off the power otherwise the machine may operate if the treadle is switch. Then contact your nearest Brother dealer or a qualified technician. depressed by mistake, which could result in injury. -
Page 5: 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. Moving parts may cause injury. -
Page 6: Table Of Contents
5-15. Adjusting the needle and rotary hook timing .................... 5-12 5-16. Adjusting the hook stopper position ......................5-12 5-17. Adjusting the rotary hook lubrication amount ................... 5-13 5-18. Adjusting the lubrication amount of the needle bar .................. 5-14 6. TROUBLESHOOTING ........................6-01 LZ2-B850,B851... -
Page 7: Machine Specifications
1. MACHINE SPECIFICATIONS 1. MACHINE SPECIFICATIONS BROTHER INDUSTRIES, LTD. BROTHER INDUSTRIES, LTD. LZ2-B851- 1 LZ2-B8503 - 3 MADE IN JAPAN MADE IN JAPAN B850 B850W B851 Plain zigzag Plain zigzag 3-step zigzag (Narrow) (Wide) Sewing pattern 0520M 0521M 0522M For light-weight materials-medium-weight materrials Maximum stitch length 2.5mm... - Page 8 * However, depending on the installation position of the motor, the V-belt size may differ from that given in the table. Pulley O.D. (mm) Belt size (inches) 50Hz 2500 3000 3500 4000 4500 5000 Sewing speed (rpm) 60Hz 3000 3500 4000 4500 5000 1-02 LZ2-B850, B851...
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Page 9: Mechanical Descriptions
3. Timing pulley U 7. Lower shaft gear 1. Pulley 6. Lower shaft 13. Rotary hook 4. Timing belt 10. Bevel gear 5. Timing pulley D 8. Driving gear 9. Driving shaft 12. Rotary hook shaft 11. Bevel gear 1090S 2-01 LZ2-B850,B851... -
Page 10: Zigzag Mechanism
8. Zigzag connecting rod 2. Upper shaft 3. Upper shaft gear 7. Roller 10. Joint 11. Needle bar bracket 1. Pulley 6. Cam 12. Needle bar Roller 5. Shaft 9. Zigzag regulator 4. Rocker gear 1093S 1094S 1095S LZ2-B850,B851 2-02... -
Page 11: Presser Foot Mechanism
3. Presser bar 9. Presser bar 2. Knee lifter shaft 10. Presser foot 4. Presser foot 1124S 1. Knee lifter 1098S 3. Guide bracket 2. Lifter lever 1. Presser bar lifter 4. Presser bar 5. Presser foot 1099S 2-03 LZ2-B850,B851... -
Page 12: Feed Mechanism
8. Spring 6. Connecting rod 7. Feed regulator 1126S Connecting rod Feed rocker arm Side connecting rod The horizontal feed amount changes when the angle of the feed regulator is changed. Feed regulator 1127S LZ2-B850,B851 2-04... - Page 13 The angle of the feed regulator when the backtack lever is pressed down can be changed by adjusting the condense dial. When the condense dial is turned to the - (minus) side of the scale, the angle of the feed regulator becomes greater and reverse feeding is carried out. 2-05 LZ2-B850,B851...
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Page 14: Lubrication
Supply oil 1108S I6. Oil cap screw with hole I5. Felt I4. Oil valve I3. Rotary hook shaft M4. Adjusting screw I M2. Oil lip M5. Bed I7. Supply oil felt M3. Bush F I8. Oil wick felt 1129S LZ2-B850,B851 2-06... -
Page 15: Tension Release Mechanism
1b. Connecting rod (When press the knee lifter) 2. Lifter lever 1a. Presser bar lifter 3. Tension release plate 4. Tension release stud 5. Tension release pin (Put the disc presser) 7. Rotary disc Tension release pin 6. Disc presser 1110S 2-07 LZ2-B850,B851... -
Page 16: Disassembly
Use only the proper replacement parts as specified rectly before using the machine. by Brother. Any problems in machine operation which result from unauthorized modifications to the machine will not be covered by the warranty. -
Page 17: Presser Mechanism
7. Two set screws 8. Thread take-up lever shaft (Loosen) 5. Needle bar 4. (Loosen) 6. Needle bar clamp 9. Needle bar connecting rod 3. Thread guide Joint 10. (Loosen) 13. Needle bar bracket assy 12. Pin F 1141S 11. (Loosen) LZ2-B850,B851 3-02... -
Page 18: Rotary Hook Mechanism
11. Rotary hook 1069S 3-5. Feed mechanism Set screw collar 5. Felt (Pull) 2. Two set screws (Loosen) 6. Feed base assy 4. Feed rocker shaft (Slide right) 1. (Loosen) 3. Two set screws (Loosen) Feed rocker arm 1070S 3-03 LZ2-B850,B851... - Page 19 7. Two set screws 8. Two set screws (*Temporarily tighten) Feed rocker arm 1070S * After adjusting the feed dog, tighten the two screws. Refer to "5-5. Adjusting the forward/back, right/left position of the feed dog" (page 5-03). 4-01 LZ2-B850,B851...
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Page 20: Needle Bar Mechanism
(Press) 9. Needle bar clamp 6. Needle bar connecting rod 1068S 14. Rubber 10. Needle 11. *Screw (Temporarily tighten) Face to front 12. Thread 1066S 1073S guide * Refer to "5-8. Adjusting the needle bar height" (page 5-06). LZ2-B850,B851 4-02... -
Page 21: Rotary Hook Mechanism
After "5-15. Adjusting the needle and rotary hook timing" (page 5-12), tighten the two set screws. After "5-16. Adjusting the hook stopper position" (page 5-12), tighten the screw. *** After "5-5. Adjusting the forward/back, right/left position of the feed dog" (page 5-03), tighten the two screws. 4-03 LZ2-B850,B851... -
Page 22: Presser Mechanism
15. (Loosen, and then tighten again after making the adjustments in 13 and 14.) 10. Presser bar lifter 1076S (Raise) 1077S 1078S 6 mm 13. (Adjust height) 11. Presser foot Align 14. (Adjust needle hole) 16. Adjustment screw 17. Adjustment nut 25 mm 1079S LZ2-B850,B851 4-04... -
Page 23: Cover
10. Face plate 14. Thread take-up mounting plate 20. Decorative plate 16. Flat screws (3 pcs) 21. Flat screws (4 pcs) 13. Flat screw 19. Decorative plate packing 18. (2 pcs) 12. Thread guide 15. Rotary thread take-up lever 1080S 4-05 LZ2-B850,B851... -
Page 24: Adjustments
Ask your Brother dealer or a qualified electrician treadle is depressed by mistake, which could re- to carry out any maintenance and inspection of the sult in injury. -
Page 25: Adjusting The Presser Foot Height
2. Tilt back the machine head. 3. Loosen the screw w. 4. Turn the pin e to move the feed bar r up and down in order to adjust the height. 5. Securely tighten the screw w. Higest position Standard Lowest position 0593M LZ2-B850,B851 5-02... -
Page 26: Adjusting The Feed Dog Angle
If adjustment is not possible, carry out the following ad- justment. <Adjusting the front and back clearances Y and the left and right clearances X> Loosen the two screws r of the level feed arm e and adjust. 1005S 5-03 LZ2-B850,B851... -
Page 27: Adjusting The Stitch Length
6. Loosen the set screw t and turn the eccentric pin y to adjust the feed amount. * After adjusting, carry out the "<Backtacking and condensed stitches>" adjustment in the next section also. LZ2-B850,B851 5-04... -
Page 28: Adjusting The Needle And Feed Mechanism Timing
⁄ mark on the connecting rod e. 5. Securely tighten the four screws r. * If the needle and feed timing has been adjusted, you should also adjust “5-15. Adjusting the needle and ro- tary hook timing”. (Refer to page 5-12.) 0600M 5-05 LZ2-B850,B851... -
Page 29: Adjusting The Needle Bar Height
“5-15. Adjusting the needle and rotary hook tim- ing” also. (Refer to page 5-12.) * When remove the feed dog. be sure to adjust “5-5. Adjusting the forward/back, right/left position of the feed dog”. (Refer to page 5-03.) 0602M LZ2-B850,B851 5-06... -
Page 30: Adjusting The Forward/Back Position Of The Needle Bar
* After adjusting, check that there is no longitudinal play in the needle bar and that it moves smoothly when zigzag- ging. * After making this adjustment, you should also carry out the adjustment in "5-10. Adjusting the right/left position of the needle bar" (Page 5-08). 5-07 LZ2-B850,B851... -
Page 31: Adjusting The Right/Left Position Of The Needle Bar
2. Loosen the set screw e and turn the eccentric position- ing shaft r to adjust. Adjust the clearances at the needle bar rocking lever q and the shaft of the zigzag adjuster w so that they are as close as possible to being equal. 1054S LZ2-B850,B851 5-08... -
Page 32: Adjusting The Base Position Of The Zigzag Width
The optimum stiffness for the zigzag width lever w is 29.4-39.2 N (for the B850) or 19.6-29.4 N (for the B851) at the lever knob. 1056S 5-09 LZ2-B850,B851... -
Page 33: Adjusting The Needle Sidewise Movement
To change the reference line, first loosen the two screws e, and then move the two stoppers r of the change le- ver w. Next loosen the thumb nut q and move the change lever w up or down. 0646M LZ2-B850,B851 5-10... - Page 34 !0 . Note: Turn the machine pulley by hand to check that the needle does not touch the presser foot and the needle plate at each reference line before sewing. 5-11 LZ2-B850,B851...
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Page 35: Adjusting The Needle And Rotary Hook Timing
* The end of the rotary hook holder q must never ex- tend to the right of end A of the inner rotary hook w. 1. Loosen the screw e and adjust the position of the ro- 0-0.5mm tary hook holder q. 2. Securely tighten the screw e. 0608M LZ2-B850,B851 5-12... -
Page 36: Adjusting The Rotary Hook Lubrication Amount
* Turn the lubrication adjustment screw e and check the lubrication amount repeatedly until the lubrica- tion amount is correct. 5. Check the lubrication amount again after the sewing machine has been used for approximately two hours. Less oil More oil 0612M 5-13 LZ2-B850,B851... -
Page 37: Adjusting The Lubrication Amount Of The Needle Bar
• In contrast, if they do not touch at all, needle zigzagging will become more and more sluggish as the sewing machine continues running, and seizure will result. LZ2-B850,B851 5-14... -
Page 38: Troubleshooting
• If the following suggestions do not solve the problem, turn off the machine power supply and contact your nearest Brother service center. CAUTION Turn off the power switch and disconnect the power cord before carrying out troubleshooting, otherwise the machine will operate if the treadle is pressed by mistake, which could result in injury. - Page 39 If an incorrect motor pulley is being used, replace 1-02 the motor pulley. • Is the angle of the feed dog incorrect? 5-03 Tilt the front of the feed dog down slightly. 0627M LZ2-B850,B851 6-02...
- Page 40 Is a bobbin other than the light-alloy bobbins specified by Brother being used? — 0628M Use only bobbins which are specified by Brother. 0629M • Is the needle bent or is the needle tip broken? 9. Upper and lower threads —...
- Page 41 SERVICE MANUAL BROTHER INDUSTRIES, LTD. 15-1, Naeshiro-cho, Mizuho-ku, Nagoya 467-8561, Japan. Phone: 81-52-824-2177 Printed in Japan 118-M50 I0120796F 2000.12 (1)