Brother LZ2-B850 Service Manual Download Page 13 | Manualshive

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2. MECHANICAL DESCRIPTIONS

LZ2-B850,B851

2-05

< Back tack mechanism >

3. Shaft

4. Condense regulator
(Touch the tip of screw)

5. Tip of screw

7. Feed regulator

6. Connecting rod

Condense dial

1. Reverse stitching lever

2. Lever guide

1102S

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.

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Summary of Contents for LZ2-B850

Page 1: ...SINGLE NEEDLE ZIGZAG LOCK STITCHER SERVICE MANUAL Please read this manual before making any adjustments LZ2 B850 B850W LZ2 B851 ...

Page 2: ... order to ensure safe operation of this machine and to prevent accidents and injury to yourself or other people The meanings of these indications and symbols are given below Indications The instructions which follow this term indicate situations where failure to follow the instruc tions could cause injury when using the machine or physical damage to equipment and sur roundings Symbols This symbol ...

Page 3: ...ning may cause problems with correct operation Environmental requirements Machine installation should only be carried out by a qualified technician Contact your Brother dealer or a qualified electrician for any electrical work that may need to be done The sewing machine weighs more than 38 kg The installation should be carried out by two or more people Do not connect the power cord until installat...

Page 4: ...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 If an error occurs in machine or if abnormal noises or smells are noticed immediately turn off the power switch Then contact your nearest Brother dealer or a qualified technician If the machine develops a problem contac...

Page 5: ...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 Safety devices q Finger guard w Thread take up guard cover e Belt cover etc 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...

Page 6: ...5 02 5 3 Adjusting the feed dog height 5 02 5 4 Adjusting the feed dog angle 5 03 5 5 Adjusting the forward back right left position of the feed dog 5 03 5 6 Adjusting the stitch length 5 04 5 7 Adjusting the needle and feed mechanism timing 5 05 5 8 Adjusting the needle bar height 5 06 5 9 Adjusting the forward back position of the needle bar 5 07 5 10 Adjusting the right left position of the nee...

Page 7: ...rials medium weight materrials 2 5mm 5mm 5 000rpm Rotary thread take up 33 3mm 1mm 6mm 10mm 20 60N Schmetz SY1965 Nm 70 10 B850W 1 2 5mm 8mm B851 1 2 5mm 3 5mm Knee lifter Presser bar lifter BROTHER INDUSTRIES LTD LZ2 B8503 3 MADE IN JAPAN BROTHER INDUSTRIES LTD MADE IN JAPAN LZ2 B851 1 Sewing pattern Plain zigzag Narrow Plain zigzag Wide 3 step zigzag Presser foot height 1 MACHINE SPECIFICATIONS ...

Page 8: ...r frequency of your area However depending on the installation position of the motor the V belt size may differ from that given in the table 1 MACHINE SPECIFICATIONS 60Hz 3000 3500 4000 4500 5000 Belt size inches Sewing speed rpm mm 50Hz 65 M42 2500 70 75 3000 80 M43 85 3500 90 95 M44 100 4000 105 110 4500 115 M45 120 5000 Pulley O D ...

Page 9: ... bar and thread take up mechanism 2 2 Lower shaft and rotary hook mechanism 1089S 5 Rotary thread take up lever 4 Thread take up lever shaft 3 Thread take up crank 2 Upper shaft 7 Needle bar 6 Needle bar clamp 5 Needle bar connecting rod 1 Pulley 2 Upper shaft 3 Timing pulley U 6 Lower shaft 7 Lower shaft gear 13 Rotary hook 10 Bevel gear 12 Rotary hook shaft 11 Bevel gear 9 Driving shaft 8 Drivin...

Page 10: ...ecting rod 11 Joint 12 Needle bar bracket 13 Needle bar 8 Cam guide 7 Link 6 Cam 4 Rocker gear 5 Shaft 10 Zigzag regulator 1 Pulley 1092S 2 Upper shaft 3 Upper shaft gear 7 Roller 8 Zigzag connecting rod 10 Joint 11 Needle bar bracket 12 Needle bar 6 Cam Roller 4 Rocker gear 5 Shaft 9 Zigzag regulator 1 Pulley 1093S 1094S 1095S ...

Page 11: ...ew 2 Presser spring 3 Presser bar 4 Presser foot 8 Guide bracket 9 Presser bar 10 Presser foot 7 Lifter lever 6 Connecting rod 5 Knee lifter lever 4 Knee lifter bar 3 Knee lifter complying bar 2 Knee lifter shaft 1 Knee lifter 3 Guide bracket 2 Lifter lever 1 Presser bar lifter 5 Presser foot 4 Presser bar 1099S ...

Page 12: ... regulator 4 Side connecting rod 2 Lower shaft end eccentric 4 Feed bracket 3 Feed lifting link 1101S 4 Connecting rod 5 Shaft 3 Feed regulator 2 Tip of screw 1 Stitch length dial 8 Spring 7 Feed regulator 6 Connecting rod The angle of the feed regulator can be changed by turning the feed adjustment dial 1126S Feed rocker arm Connecting rod Side connecting rod Feed regulator The horizontal feed am...

Page 13: ...ator 6 Connecting rod Condense dial 1 Reverse stitching lever 2 Lever guide 1102S 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 ...

Page 14: ...otary hook shaft Lubrication adjustment screw Adjust the lubrication amount B C Filter A 2 Oil case 1 Plunger pump 1106S 1107S 1108S Absorb oil Supply oil C A B From filter 1128S 1129S 6 Oil cap screw with hole 5 Felt 4 Oil valve 3 Rotary hook shaft 8 Oil wick felt 7 Supply oil felt M2 Oil lip M4 Adjusting screw M5 Bed M3 Bush F ...

Page 15: ...ension release mechanism 2 Lifter lever 1a Presser bar lifter 1b Connecting rod When press the knee 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 ...

Page 16: ...our skin otherwise inflammation may result Further more do not drink the oil or eat the grease un der any circumstances as they may cause vom iting and diarrhea Keep the oil out of the reach of children If any safety devices have been removed be absolutely sure to re install them to their origi nal positions and check that they operate cor rectly before using the machine Any problems in machine op...

Page 17: ...r 8 Loosen 3 Adjustment nut Loosen 10 Presser bar 9 Guide bracket 11 Cushion 1065S 1 2 Presser foot 1125S 1 Rubber cap 5 Needle bar 4 Loosen 3 Thread guide 2 1066S 8 Thread take up lever shaft 6 Needle bar clamp 9 Needle bar connecting rod 7 Two set screws Loosen 1068S 13 Needle bar bracket assy 11 Loosen 12 Pin F 10 Loosen Joint 1141S ...

Page 18: ...ws 1 Slide plate 3 Needle plate 5 Auxiliary needle plate 1075S 9 Rotary hook holder 8 6 Two screws 7 Feed dog 10 Two set screws Loosen 11 Rotary hook 1069S 6 Feed base assy 5 Felt Pull 3 Two set screws Loosen 4 Feed rocker shaft Slide right Feed rocker arm Set screw collar 1 Loosen 2 Two set screws Loosen 1070S ...

Page 19: ...ink 3 Feed base assy 1071S 6 Set screw collar Press right and tighten two set screws Spacer Retaining ring 5 Feed rocker shaft Press left 1072S Feed base assy Felt Feed rocker shaft 8 Two set screws Temporarily tighten Feed rocker arm 7 Two set screws 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 ...

Page 20: ...ew 2 Pin F 5 After 5 10 Adjusting the right left position of the needle bar P 5 08 tighten the screw 1142S 7 Thread take up lever shaft Press 9 Needle bar clamp 6 Needle bar connecting rod 8 Two set screws Thread take up crank 1068S 14 Rubber cap 10 Needle bar 11 Screw Temporarily tighten 13 12 Thread guide 1066S 1073S Refer to 5 8 Adjusting the needle bar height page 5 06 Face to front ...

Page 21: ...feed dog 4 Two set screws Temporarily tighten 3 Rotary hook 1074S 10 Two flat screws 12 Two flat screws 13 Slide plate 9 Needle plate 11 Auxiliary needle plate 1075S 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 fee...

Page 22: ...hten Refer to below 9 Adjustment nut 1 Presser bar 3 Guide bracket 2 Cushion 1065S 6 mm 13 Adjust height 1077S 15 Loosen and then tighten again after making the adjustments in 13 and 14 10 Presser bar lifter Raise 12 11 Presser foot 1078S Align 14 Adjust needle hole 20 30 20 30 25 mm 16 Adjustment screw 17 Adjustment nut 1079S 1076S ...

Page 23: ...ke up mounting plate 16 Flat screws 3 pcs 18 2 pcs 15 Rotary thread take up lever 13 Flat screw 12 Thread guide 2 Rear cover 10 Face plate 3 7 pcs 1 Rear cover packing 9 Face plate packing 4 Oil guard 5 2 pcs 7 Top cover 6 Top cover packing 8 7 pcs 20 Decorative plate 21 Flat screws 4 pcs 19 Decorative plate packing 1080S ...

Page 24: ...me adjustment be extremely careful to observe all safety precautions 5 1 Adjusting the thread tension spring Thread tension spring position The standard position of the thread tension spring q is 6 8 mm above the surface of the thread guide e when the presser foot w is lowered 1 Lower the presser foot w 2 Loosen the set screw r 3 Turn the thread tension bracket t to adjust the spring position 4 Se...

Page 25: ... foot q will also rise 4 Loosen the screw u and move the presser bar i up and down to adjust the height of the presser foot q to 6 mm 5 Tighten the bolt u 6 Adjust the presser foot pressure using the adjustment screw y and then tighten the nut t 7 Install the thread take up guard r with the two screws e 5 3 Adjusting the feed dog height q 1mm The standard height when the feed dog q is at its highe...

Page 26: ...he feed dog q so that the front is raised tends to prevent material from slipping uneven material feeding Figure B 5 Securely tighten the set screws r When the angle of the feed dog q is adjusted the height and forward back position of the feed dog q will also change and will need to be readjusted 5 5 Adjusting the forward back right left position of the feed dog Adjust the clearances X at the lef...

Page 27: ...rned any further clockwise even when this is done If the feed adjustment dial can be turned further turn it until it cannot turn any further Loosen the screw r turn only the dial section of the feed adjustment dial q so that the stopper w touches the pin e and then tighten the screw r If adjusting the forward feed amount and reverse feed amount so that they are the same 3 Set the feed adjustment d...

Page 28: ... it is slightly to the left or the right of the 0 position Repeat steps 2 and 3 until the zero position for the material feed amount is located 4 When the zero position for the material feed amount has been located loosen the screw o turn only the dial section of the condense stitch adjustment dial u to the 0 position and then re tighten the screw o 5 7 Adjusting the needle and feed mechanism timi...

Page 29: ...hine pulley to move the needle bar q to its lowest position 4 Loosen the screw u 5 Move the needle bar q up or down to adjust the dis tance from the top of the auxiliary needle plate w to the bottom edge of the needle bar q so that it is the same as the height of accessory timing gauge 1 e Note The needle plate t and the auxiliary needle plate w are of different thicknesses so be sure to use the a...

Page 30: ...dinal play in the needle bar and that it moves smoothly when zigzagging 1 Remove the presser foot while making this adjustment 2 Loosen the two set screws hexagonal screws 2 mm diagonally opposite each other q and then push pin R w or pin F e to adjust Turn the machine pulley and check that the needle moves down into the center of the needle plate hole 3 Securely tighten the two screws q After adj...

Page 31: ...e to the left or right to adjust Turn the machine pulley and check that the needle moves down into the center of the needle plate hole 3 Securely tighten the screw w 5 11 Adjusting the forward back position of the zigzag regulator Adjust so that the needle bar rocking lever q and the zig zag adjuster w move easily 1 Remove the head cover the oil guard and the decora tive plate while making this ad...

Page 32: ... the needle above the material when adjusting the zigzag width If the zigzag width is adjusted while the needle is piercing the material the needle may bend The numbers on the scale of the decorative plate q indicate the zigzag width in mm The scale is a guide only if the width of the finished zigzag stitches differs greatly from the scale value make the fol lowing adjustment If the above adjustme...

Page 33: ...eedle deflection when the needle goes into the needle plate hole is as small as pos sible 1 Remove the head cover and the oil guard while mak ing this adjustment 2 Loosen the screws q two for the B850 four for the B851 and turn the upper shaft gear w to adjust Adjust so that the needle path describes a reversed U shape when the machine pulley is turned For B850 1 Narrow specifications Note If the ...

Page 34: ...g selector w aligned with each other tighten the screw 1 so that it is seated in the recess of the needle positioning plate t The change lever will drop four steps Loosen the thumb nut e loosen the screw r and then move the needle positioning plate t to move the change lever y in order to adjust the center reference line After making this adjustment you should also carry out the adjustment in 5 10...

Page 35: ... so be sure to use the auxil iary needle plate q 5 If the above are not correct loosen the two screws t and adjust the position of the rotary hook y After adjustment securely tighten the two screws t 6 Set the zigzag width to the maximum setting B850 5mm B850W B851 8mm 7 Turn the machine pulley to move the needle to its fur thest left position so that the tip of the rotary hook r is aligned with t...

Page 36: ...art stop pattern as when actually sewing 2 Place the lubrication amount check sheet q to the left of the rotary hook w and hold it there Then run the sewing machine at the normal sewing speed for 10 seconds Any type of paper can be used as the lubrication amount check sheet q 3 Check the amount of oil which has spattered onto the sheet Be sure to repeat this operation three to four times to check ...

Page 37: ...on while making this adjustment 2 Turn the machine pulley and adjust the position of the needle bar lubrication support r so that the projection on the needle bar connecting rod q is slightly touching the wick e Loosen the two screws t to adjust Note If the projection on the needle bar connecting rod q is touching the wick e too firmly the amount of oil leaking around the needle bar will increase ...

Page 38: ...nstall the needle correctly Is the machine properly threaded If it is incorrect thread the thread correctly Is the presser foot pressure too weak Adjust the presser foot pressure Is the needle too thin Replace the needle with a needle that is one rank thicker Is the presser foot too high Adjust the height of the presser foot Is the needle and rotary hook timing incorrect Adjust the height of the n...

Page 39: ... the needle Use the correct needle or the correct thread Is the rotary hook bobbin case thread take up lever or some other part in the thread path damaged Repair the damage or replace the part with a new one 0625M 5 01 5 01 1 02 5 03 7 Large degree of puckering excess tension Is the upper thread tension too strong Make the upper thread tension as weak as possible Is the lower thread tension too st...

Page 40: ... because the thread tension spring operating range is too small Adjust the position of the thread tension spring Is the needle and rotary hock timing incorrect Adjust the height of the needle bar Adjust the clearance between the needle and the rotary hock Is the thread too thick for the needle Use the correct needle or the correct thread Is the rotary hook bobbin case thread take up lever or some ...

Page 41: ...SERVICE MANUAL Printed in Japan 118 M50 I0120796F 2000 12 1 BROTHER INDUSTRIES LTD 15 1 Naeshiro cho Mizuho ku Nagoya 467 8561 Japan Phone 81 52 824 2177 ...

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