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Brother LH4-B800E Service Manual

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LH4 - B800E
SERVICE MANUAL
Please read this manual before making any adjustments.
ELECTRONIC LOCKSTITCH BUTTON HOLER

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Table of Contents

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   Summary of Contents for Brother LH4-B800E

  • Page 1 LH4 - B800E SERVICE MANUAL Please read this manual before making any adjustments. ELECTRONIC LOCKSTITCH BUTTON HOLER...
  • Page 2 Thank you very much for buying a BROTHER sewing machine. Before using your new machine, please read the safety instruc- tions 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 lever, and consequently there is always a danger of injury that can be caused by these parts.
  • 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.
  • Page 4 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 pressed by mistake, which could result in injury. qualified technician.
  • Page 5 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 re- moved or are difficult to read, please contact your nearest Brother dealer. Hazardous voltage Hochspannung Un voltage non adapté...
  • Page 6: Table Of Contents

    3-10. Needle bar and thread take-up mechanism ..... 3-18 3-11. Presser bar mechanism ........... 3-20 3-12. Upper thread trimmer mechanism ........3-21 3-13. Thread breakage detection mechanism ......3-23 3-14. Lubrication mechanism ............ 3-24 3-15. Rotary hook mechanism ..........3-31 LH4-B800E...
  • Page 7 Fuse explanation ......................6-3 6-4. Connectors ......................... 6-4 6-5. Description of DIP switches ..................6-22 6-6. Description of machine motor parameters ..............6-26 6-7. Error code table ......................6-27 6-8. Troubleshooting ......................6-29 6-9. Control circuit block diagram ..................6-34 LH4-B800E...
  • Page 8: Mechanism Description

    3. The needle bar !1 is secured to the needle bar clamp u, and it moves smoothly up and down while being guided by the bushings at the top and bottom of the needle bar guide !2 and needle bar bracket !3 . LH4-B800E 1 - 1...
  • Page 9: Upper Shaft, Lower Shaft And Rotary Hook Mechanism

    3. The timing pulley t is secured to the lower shaft y, and it transmits the rotation to the rotary hook joint u that is secured to the end of the lower shaft y. 4. The rotary hook i is secured to the rotary hook joint u and rotates fully together with the rotary hook joint u. LH4-B800E 1 - 2...
  • Page 10: Needle Zigzag Mechanism

    F assembly r to move in a reciprocal motion. 3. The needle bar bracket slide block t is linked to the groove in the needle bar bracket y and causes the needle bar bracket y to move in a reciprocal motion. LH4-B800E 1 - 3...
  • Page 11: Presser Foot Lifter Mechanism

    5. Feed arm support ! 4 that is connected to the feed arm ! 3 is hooked onto the presser roller bracket ! 2 , and it moves the work clamp ! 5 up and down. LH4-B800E 1 - 4...
  • Page 12: Feed Mechanism

    3. The feed arm i is connected to the feed arm support t, and it moves the work clamp o that is installed to the feed arm i and the length feed plate !0 that is installed to the feed arm support t back and forth. LH4-B800E 1 - 5...
  • Page 13: Cutter Mechanism

    4. The driving shaft holder assembly y is linked to the cutter driving link t, and this causes the cutter driving shaft u that is connected to the driving shaft holder assembly y to move up and down. LH4-B800E 1 - 6...
  • Page 14: Thread Breakage Detection Mechanism

    When a thread breakage occurs, the cutter bar fixed plate assembly q drop by its own weight and moves the thread guide w in the direction of the arrow. 2. When the sensor r detects the cutter bar fixed plate assembly q, the sewing machine stops and the cutter is prevented from dropping. LH4-B800E 1 - 7...
  • Page 15: Lubrication Mechanism

    4. The oil which collects in the jaw of the arm, is absorbed by the felt @ 3 and is drawn up by the plunger pump w through the tube (D), and it is then returned to the oil tank (E) by the plunger pump w. LH4-B800E 1 - 8...
  • Page 16 3. The oil that is supplied to the rotary hook u can be adjusted by turning the screw i to vary the amount by which the rubber presser o presses down on the collar !0 that the wick passes through. LH4-B800E 1 - 9...
  • Page 17: Tension Release Mechanism

    3. The tension release link r that is connected to the tension release solenoid link e operates with the shoulder screw t as a pivot and presses against the tension release pin y. 4. The tension release pin y presses against the tension disc presser u to release the tension discs. LH4-B800E 1 - 10...
  • Page 18 !2 moves in the direction of the arrow. 6. When the tension release cam !2 presses against the tension release pin !3 , the tension release pin !3 presses against the tension disc presser !4 to release the tension discs. LH4-B800E 1 - 11...
  • Page 19: Upper Thread Trimmer Mechanism

    (6) The upper thread is thread scissors gradually start to clamped and cut. open. (3) After approximately 4.6 mm of feed, (4) Sewing ends. (5) The upper thread scis- the upper thread scissors are fully sors move forward. pen. LH4-B800E 1 - 12...
  • Page 20 @ 2 that is secured to the setting plate @ 1 . 9. Upper thread trimmer M @3 that is installed to the upper thread trimmer assembly @2 comes into contact with the work clamp, so that upper thread trimmer M @3 closes and cuts the thread. LH4-B800E 1 - 13...
  • Page 21 (Figure B). At this time, section D of the opening cam e fits into the upper thread trimmer assembly t so that the upper thread trimmer assembly t cannot move in the direction of arrow C. LH4-B800E 1 - 14...
  • Page 22 Figure A to the one in Figure B and the upper thread trimmer opens fully. LH4-B800E 1 - 15...
  • Page 23: Lower Thread Trimmer Mechanism

    !0 that is connected to the lower thread trimmer cam o. LH4-B800E 1 - 16...
  • Page 24 ! 3 that is secured to the fixed knife ! 2 moves over the cam section of the base plate !4 so that the movable knife !3 starts to close. When the lower thread retainer i has finished operating, the movable knife !3 meshes fully with the fixed knife !2 and cuts the lower thread. LH4-B800E 1 - 17...
  • Page 25 12. The opening plate w presses against the collar u that is installed to the lower thread clamp y and the lower thread clamp y rotates centering on the shoulder screw i, so that the clamped lower thread is released by the lower thread presser o and the lower thread clamp y. LH4-B800E 1 - 18...
  • Page 26: Disassembly

    Loosen the set screw y, and then remove the timing pulley assembly u from the lower shaft t. Loosen the two set screws i, and then remove the shaft o. Remove the collar ! 0 and the idle pulley assembly ! 1 . LH4-B800E 2 - 1...
  • Page 27: Lower Thread Trimmer Assembly

    Remove the two screws @ 6 , and then remove the lower thread retainer @ 7 from the lever assembly @ 8 . Remove the collar @ 9 and the screw # 0 , and then remove the lever assembly @ 8 from the base plate o. Remove the screw # 1 . LH4-B800E 2 - 2...
  • Page 28 Remove the retaining ring @ 5 , and then remove the roller ! 7 . Remove the nut @ 6 , and then remove the roller shaft @ 7 from the lower thread trimmer cam lever ! 1 . LH4-B800E 2 - 3...
  • Page 29: Feed Mechanism

    Remove the two retaining rings # 4 , and then remove the linear bush # 5 from the feed arm support ! 7 . Remove the screw # 6 , and then remove the ball bearing stopper # 7 . Remove the two feed shaft linear bushes #8 . LH4-B800E 2 - 4...
  • Page 30 Remove the two ball bearing stoppers B (for long-hole) r, and then remove the two linear bushes t. Remove the screw y, and then remove the linear bush stopper plate (for long-hole) u. Remove the linear bush 9.53 (for long-hole) i from the feed arm support -5 (for long-hole) o. LH4-B800E 2 - 5...
  • Page 31 Remove the eye bolt ! 7 and the flat washer ! 8 , and then remove the feed cover ! 9 from the feed arm support ! 0 . Remove the two eye bolts @2 and the two spring washers @3 , and then remove the length feed plate @4 from the feed arm support !0 . LH4-B800E 2 - 6...
  • Page 32: Bobbin Presser Mechanism

    Loosen the set screw o, and then remove the bobbin presser !0 from the bobbin presser bracket y. Remove the screw ! 1 and the nut ! 2 . Remove spring hook U ! 3 . LH4-B800E 2 - 7...
  • Page 33: Tension Release Mechanism

    Remove the plunger pin !3 , and then remove the plunger !1 and the tension release solenoid link !5 . Remove the two screws !6 , and then remove the tension release solenoid !7 from the solenoid holder !8 . LH4-B800E 2 - 8...
  • Page 34 Remove the shoulder screw @ 9 and the washer # 0 , and then remove the lever # 1 from the adjusting lever # 2 . Remove the two shoulder screws #3 , and then remove the adjusting lever #2 and the tension take-up lever #4 from the lever link #5 . LH4-B800E 2 - 9...
  • Page 35: Presser Lifter Mechanism

    Loosen the four set screws ! 9 , and then remove the two guide shafts @ 0 and the guide bracket ! 8 . Remove the bolt ! 5 , and then remove the bearing holder @ 1 . Remove the two linear ball bearings @ 2 from the guide bracket ! 8 . LH4-B800E 2 - 10...
  • Page 36 Remove the set screw t, and then remove the gear 15.75 y from the pulse motor FT assembly (for presser lifter) e. Remove the set screw u, and then remove the motor lever i from the pulse motor N assembly (for needle zigzag) LH4-B800E 2 - 11...
  • Page 37 Remove the two O-rings ! 8 and the two trimmer driving levers ! 9 . Remove the spacer @ 2 , plain washer D @ 3 and bolt @ 4 , and then remove the knee lifter lever @ 5 from the presser lifter connecting rod assembly @ 6 . LH4-B800E 2 - 12...
  • Page 38: Needle Zigzag Mechanism

    Remove the thrust washer !3 and the zigzag lever !4 , and then remove the zigzag lever F assembly !5 . Loosen the set screw @2 , remove the zigzag connecting rod shaft @0 and then remove the zigzag lever !4 and the zigzag connecting rod y. LH4-B800E 2 - 13...
  • Page 39: Cutter Mechanism

    Remove the nut !5 , and then remove the adjusting screw assembly !6 from the arm. Loosen the two set screws ! 7 , and then remove the cutter driver shaft o. Remove the oil rejector !8 . LH4-B800E 2 - 14...
  • Page 40 Remove the three bolts ! 4 , and then remove the cutter solenoid w from the cutter solenoid bracket t. Remove the spring washer ! 5 and the two nuts ! 6 , and then remove the solenoid stopper ! 7 from the solenoid flange. LH4-B800E 2 - 15...
  • Page 41: Upper Shaft And Tension Pulley Mechanism

    Loosen the two set screws ! 4 , and then remove the bobbin winder pulley ! 5 . Loosen the set screw !6 , and then remove the timing pulley U assembly !7 . Remove the timing belt ! 8 . Remove the bearing ! 9 . LH4-B800E 2 - 16...
  • Page 42: Needle Bar And Thread Take-up Mechanism

    Remove the bolt !9 , and then remove the needle bar guide @0 from the needle bar bracket assembly !3 . Loosen the screw @ 3 of the needle bar clamp ! 4 , and then remove the needle bar @ 1 . LH4-B800E 2 - 17...
  • Page 43 Remove the thread take-up lever set u and the washer i from the thread take-up crank o. Remove the needle bar bracket slide block t. Remove the two bolts ! 0 and the screw ! 1 , and then remove the crank rod guide y. LH4-B800E 2 - 18...
  • Page 44: Presser Bar Mechanism

    Remove the plain washer ! 9 and the retaining ring @ 0 , and then remove the roller @ 1 from the roller shaft ! 8 . Remove the shoulder screw @5 , and then remove the presser bar lifter link @6 from the presser bar guide bracket @4 . LH4-B800E 2 - 19...
  • Page 45: Upper Thread Trimmer Mechanism

    2. DISASSEMBLY 2-12. Upper thread trimmer mechanism Remove the screw q, spring washer w and plain washer e, and then remove the upper thread trimmer assembly r from the upper thread trimmer lever t. LH4-B800E 2 - 20...
  • Page 46 Remove the screw $1 , and then remove the spring hook plate $2 from the upper thread trimmer lever assembly #3 . Remove the rubber cap $ 3 . Loosen the set screw $ 5 of the set screw collar assembly $ 4 , and then remove the upper thread trimmer fulcrum shaft @ 9 . LH4-B800E 2 - 21...
  • Page 47: Thread Breakage Detection Mechanism

    Take the thread breakage perceiving shaft o out from the arm. Remove the plain washer ! 2 , plain washer ! 3 and screw ! 4 , and then remove the thread guide !5 from the thread breakage perceiving shaft o. LH4-B800E 2 - 22...
  • Page 48: Lubrication Mechanism

    Remove the screw q, and then remove tube support U w. Remove the wicks e and r, and then disconnect the oil tube t. Remove the felt y, and then remove the wick u from bush F i. LH4-B800E 2 - 23...
  • Page 49 2. DISASSEMBLY Needle zigzag mechanism Remove the screw q, and then remove the felt support w from the motor bracket e. Remove the screw r, and then remove the tube support t. LH4-B800E 2 - 24...
  • Page 50 Remove the screw ! 2 , and then remove the felt holder ! 3 . Remove the felt ! 4 , and then disconnect the oil tube u. LH4-B800E 2 - 25...
  • Page 51 Remove the oil cap @ 1 , and then remove the packing @ 2 from the oil terminal ! 5 . Remove the collar @ 3 and the wick @ 4 from the oil terminal ! 5 . LH4-B800E 2 - 26...
  • Page 52 Remove the oil tube ! 9 from the inlet hole to the right of bush M ! 4 . Remove the two screws @0 , and then remove the two plungers @1 and the two compression springs @2 from bush M !4 . LH4-B800E 2 - 27...
  • Page 53 Remove the end of the felt i from the bush o. Remove the spring ! 0 from the bush o. Remove the collar ! 1 from the bush o. Remove the wick y from the collar !1 . LH4-B800E 2 - 28...
  • Page 54: Rotary Hook Mechanism

    Remove the two screws q, and then remove the rotary hook holder w. Loosen the set screw e, and then remove the rotary hook r. Loosen the set screw t, and then remove the rotary hook joint assembly y. LH4-B800E 2 - 29...
  • Page 55 2. DISASSEMBLY LH4-B800E 2 - 30...
  • Page 56: Assembly

    After checking the thrust direction, securely tighten the set screw o. The screw stop position is the start of the rotation direction. Install the cover ! 0 with the two screws ! 1 . LH4-B800E 3 - 1...
  • Page 57: Lower Thread Trimmer Mechanism

    Connect the lower thread trimmer link assembly @ 2 and the lower thread trimmer cam connecting rod y with the shoulder screw @4 . Install the opening plate assembly @5 with the shoulder screw @6 . Install the plate spring @7 as shown in the illustration. LH4-B800E 3 - 2...
  • Page 58 Install the length feed plate @ 9 to the feed arm support # 0 with the bolt # 1 and washer # 2 . Install the feed presser plate #3 with the screw #4 so that the feed mechanism moves easily when it is moved back and forth by hand. LH4-B800E 3 - 3...
  • Page 59: Feed Mechanism

    Pass the cords for the feed pulse motor !9 , DC fan motor 40 assembly @7 and feed home position sensor #1 through the cord holder #6 and the cord supports #7 as shown in the illustration, and secure to the bed with the screw #8 and the plain washer #9 . LH4-B800E 3 - 4...
  • Page 60 B-5 (for long-hole) !0 is aligned with the edge of the feed arm support -5 (for long-hole) o. Install feed guide shaft A-5 (for long-hole) i to the bed so that the feed arm support -5 (for long-hole) o moves smoothly. LH4-B800E 3 - 5...
  • Page 61 Insert the spring @0 into the work clamp !9 , and then install the work clamp !9 to the feed arm assembly !6 with the shoulder screw @1 . Install the feed arm support @2 and the opening cam assembly @3 to the feed arm assembly !6 with the two screws @ 4 . LH4-B800E 3 - 6...
  • Page 62: Bobbin Presser Mechanism

    Turn on the power. After the mechanism moves to the home position, turn the screw e and the nut r to adjust so that the clearance between the bobbin presser t and the edge of the bed is approximately 12.5 mm. LH4-B800E 3 - 7...
  • Page 63: Tension Release Mechanism

    With the tension release link !1 pushed in the direction of the arrow (B) (Figure C), move the tension release solenoid assembly !3 so that the tension discs are open by 0.5 to 1 mm, and then tighten the screw !4 . LH4-B800E 3 - 8...
  • Page 64 #4 to the tension stud assembly #3 . Then attach the spring #5 . Install the tension release lever #6 with the shoulder screw # 7 so that the spring # 5 is straight. Then fully tighten the tension stud assembly # 3 . LH4-B800E 3 - 9...
  • Page 65: Presser Lifter Mechanism

    Install the driving lever roller @2 to the trimmer driving lever o with the shoulder screw @3 . Install the ball bearing @4 to the trimmer driving lever o with the shoulder screw @3 . Install the presser lifter connecting rod set y to the arm with lifter shaft A @ 5 and the set screw @ 6 . LH4-B800E 3 - 10...
  • Page 66 Install the pulse motor N assembly (for needle zigzag) q and the pulse motor FT assembly (for presser lifter) r to the motor bracket u with the bolts i so that the directions of the cords are as shown in the illustration. (Motor bracket assembly o) LH4-B800E 3 - 11...
  • Page 67 Install the clamp sensor plate @4 with the pan screw @5 . Install the sensor @6 with the screw @7 . Install the clamp sensor dog @8 to the upper thread trimmer driving link #0 with the two screws @9 . LH4-B800E 3 - 12...
  • Page 68: Needle Zigzag Mechanism

    @ 0 by tightening the set screw ! 9 . Install the zigzag sensor plate !5 to the motor bracket @2 with the screw @1 so that the screw @1 is in the middle of the slot. LH4-B800E 3 - 13...
  • Page 69: Cutter Mechanism

    Install the cutter solenoid bracket !3 to the arm with the four screws @6 . Check that the plunger of the cutter solenoid !1 moves easily. Insert the oil tube @7 and the cord of the cutter solenoid !1 in between tube support U @8 and the arm. LH4-B800E 3 - 14...
  • Page 70 M !9 with the screw @2 . Install the cutter @3 to cutter holder DL @1 with the screw @4 . Fully tighten the bolts ! 8 and @ 0 so that the cutter @ 3 is in the center of the cutter groove in the needle plate @ 5 when the cutter is lowered. LH4-B800E 3 - 15...
  • Page 71 Tighten the screw @4 so that the top of the cutter blade and the top of the needle plate are aligned when the cutter @3 is pushed down manually to its lowest position. For a flat cutter @8 , tighten the screw @4 so that it is 1.5 to 2 mm from the top of the needle plate. LH4-B800E 3 - 16...
  • Page 72: Upper Shaft And Tension Pulley Mechanism

    Install the synchronizer assembly H80 ! 9 to the arm with the screw @ 0 . Install the pulley assembly @1 with the screw @2 so that the screw stop is at the front, and so that the clearance between it and the synchronizer assembly H80 !9 is 0.5 mm. LH4-B800E 3 - 17...
  • Page 73: Needle Bar And Thread Take-up Mechanism

    Insert the needle bar bracket slide block r into the groove in the crank rod guide q. Secure the thread take- up lever set t by tightening the two set screws i. Insert the support shaft !0 and secure it by tightening the set screw !1 so that the thread take-up moves smoothly with no play. LH4-B800E 3 - 18...
  • Page 74 When the needle bar w is at its maximum zigzag position, tighten the set screws !5 and !8 against the needle bar bracket assembly q, and then loosen them again by about 1/4 of a turn each. Then tighten the nuts !6 and !9 . Insert the needle bar thread guide @0 into the needle bar w. LH4-B800E 3 - 19...
  • Page 75: Presser Bar Mechanism

    @5 . Then remove the gauge @4 and turn off the power. Insert the spring guide @6 , compression spring @7 and plain washer @8 , and with the presser adjusting screw @9 at a height of 30 mm, tighten the presser adjusting nut #0 . LH4-B800E 3 - 20...
  • Page 76: Upper Thread Trimmer Mechanism

    #6 are aligned. Tighten the eye bolt @4 so that the stop plate i and the stopper #2 are in the positions shown in the illustration. Attach the two springs $4 to the upper thread trimmer lever set #5 . Attach the larger hooks of the springs $4 to the pins $5 on the arm. LH4-B800E 3 - 21...
  • Page 77 3. ASSEMBLY Install the upper thread trimmer assembly q to the upper thread trimmer lever w with the screw r, spring washer t and plain washer y. LH4-B800E 3 - 22...
  • Page 78: Thread Breakage Detection Mechanism

    Install the balancer ! 0 to the cutter bar fixing plate i with the screw ! 1 . Install the lever stopper ! 2 at the correct angle with the screw ! 3 . Provisionally install the lever stopper ! 4 with the screw ! 5 . LH4-B800E 3 - 23...
  • Page 79: Lubrication Mechanism

    At this time, push in firmly so that the wick r inside bush F w is touching the wick q and is also touching the upper shaft t. * If the wick is not pushed in firmly enough, seizure of the upper shaft may occur. LH4-B800E 3 - 24...
  • Page 80 U w and push it firmly into the zigzag lever shaft lubrication hole. Install tube support U w with the screw r. Pass the oil tube t around the outside of tube support U w as shown in the illustration. LH4-B800E 3 - 25...
  • Page 81 Pass the oil tube q around the outside of tube support U w as shown in the illustration so that it does not touch the solenoid stopper !1 , and then pass it in between the cutter solenoid !2 and the arm. LH4-B800E 3 - 26...
  • Page 82 ! 4 , pass it through the arm hole ! 5 , and then secure it to the arm with the fastening band ! 6 . At this time, bind the oil tube carefully so as not to break it. LH4-B800E 3 - 27...
  • Page 83 @3 , and then install them to the wick base support !0 . Install felt base A ! 9 with the screw @ 4 . Insert the felt @ 8 , and then install the cap @ 6 with the screw @ 7 . LH4-B800E 3 - 28...
  • Page 84 Insert the oil tube oil tube u that is connected between the plunger and the filter through the oil filter bracket @1 . Install the oil filter bracket @ 1 to the bed with the three screws @ 2 . LH4-B800E 3 - 29...
  • Page 85 As a guide to the rotary hook lubrication amount, fully tighten the screw !1 , and then loosen it by about two turns. To check and adjust the lubrication amount, refer to "4-22. Adjusting the rotary hook lubrication". LH4-B800E 3 - 30...
  • Page 86: Rotary Hook Mechanism

    (A) of the hook e and the lubrication port (B) of the rotary hook joint assembly q are aligned. Then adjust the needle clearance and timing. Install the rotary hook holder t with the two screws y. LH4-B800E 3 - 31...
  • Page 87 3. ASSEMBLY LH4-B800E 3 - 32...
  • Page 88: Adjustment

    Operate the feed mechanism when the condition is as shown in diagram A. If it is pushed in the direction of arrow (b) at the condi- tion shown in diagram B, the condition will change to that shown in diagram A. LH4-B800E 4 - 1...
  • Page 89: Adjusting The Needle Zigzag Home Position Sensor Position

    If the needle bar is at its furthest zigzag position, place the stopper screws r and t against the needle bar bracket e, and then turn then back about 1/4 of a turn. Then tighten the nuts y and u. LH4-B800E 4 - 2...
  • Page 90: Adjusting The Feed Home Position Sensor Position

    If the clearance is not 2 mm, turn off the power. 3. Loosen the screw e and adjust the position of the feed sensor support plate r. 4. Repeat the procedure from step 1. LH4-B800E 4 - 3...
  • Page 91 If the clearance is not 2 mm, turn off the power. 3. Loosen the screw e and adjust the position of the feed sensor support plate r. 4. Repeat the procedure from step 1. LH4-B800E 4 - 4...
  • Page 92: Adjusting The Presser Foot Home Position Sensor Position

    Make this adjustment before carrying out "4-13. Adjusting the upper thread trimming". After making this adjustment, check the tension release of the tack tension control and the upper thread trimming, and adjust if necessary by referring to the respective adjustment procedures. LH4-B800E 4 - 5...
  • Page 93: Adjusting The Needle Bar Height

    Different gauges are used for each of the three sub-classes -2, -3 and -5, so make sure that the gauge being used matches the specifications and application for the sewing machine being adjusted. LH4-B800E 4 - 6...
  • Page 94 K n i t t e d wear S13596-001 Gauge 815-3 3.2 mm Knitted +0.1 12.7 wear (-3) +0.1 16.2 S13597-001 Gauge 805-2 Long-hole +0.1 specifica- 14.2 tions 805-2 +0.1 (-5) 16.7 Thin knitted wear 2.5 mm LH4-B800E 4 - 7...
  • Page 95: Adjusting The Inner Rotary Hook And Rotary Hook Holder Overlap

    Furthermore, it may also cause the presser foot lifter pulse motor to go out of step. LH4-B800E 4 - 8...
  • Page 96: Adjusting The Work Clamp Lateral Position

    1. Loosen the screw q, and then adjust the knife sensor assembly r so that there is a clearance of 4.5 ± 0.5 mm between the side of the sensor w and the edge of the solenoid stopper e. LH4-B800E 4 - 9...
  • Page 97: Adjusting The Knife Installation Position

    When the screw u has been loosened, check that the edge of the cutter holder is touching the stepped section of the cutter driving shaft i, and then tighten the screw u. After adjusting, push the upper thread trimmer assembly w back to its original position (Fig. A). LH4-B800E 4 - 10...
  • Page 98: Adjusting The Cutter Installation Height

    For the flat cutter e, install with the screw w so that the top q of the cutter blade is 1.5—2 mm above the top of the needle plate. After adjusting, push the upper thread trimmer assembly w back to its original position (4-11 Fig. A). LH4-B800E 4 - 11...
  • Page 99: Adjusting The Upper Thread Trimming

    4-13-5 Adjusting the installation height of the upper thread scissors 4-13-6 Adjusting the upper thread scissors gradual opening timing 4-13-7 (8) (4) (3) (2) (2) Adjusting the upper thread scissors opening timing (9) (5) (4) 4-13-8 LH4-B800E 4 - 12...
  • Page 100 1 mm. If adjustment is necessary, loosen the bolt t and move the trimmer driving arm assembly q back and forward to adjust. LH4-B800E 4 - 13...
  • Page 101 U r is aligned with the edge of the needle hole. If the above adjustment is not carried out, it may result in thread trimming errors or needle breakages. LH4-B800E 4 - 14...
  • Page 102 0—0.5 mm. If the stopper y is adjusted so that it presses too firmly, it may cause the presser foot lifter pulse motor to go out of step. LH4-B800E 4 - 15...
  • Page 103 If the upper thread scissors t are touching the work clamp y, it may cause the presser foot lifter pulse motor to go out of step. If the tilting of the work clamp y causes skipped stitches to occur when sewing material joints, use the accessory auxiliary sheet u as shown in the illustration. LH4-B800E 4 - 16...
  • Page 104 Check that the upper thread scissors e gradually start opening after the material has been fed by 1.5—2.5 mm. Apply grease to edge surface (C). LH4-B800E 4 - 17...
  • Page 105 Then tighten the screw i, turn the power back on, set the sewing machine to the home position nd then press the RESET key to check the adjustment. 4. Check the operation in test feed mode. Refer to the operating procedure given in “1-10. Upper thread trimmer mechanism”. LH4-B800E 4 - 18...
  • Page 106: Adjusting The Lower Thread Trimming

    <If the lower thread retaining amount is too great> This can cause problems such as poor sealing at the sewing start, or wound lower thread sticking out of the rear tack. LH4-B800E 4 - 19...
  • Page 107 If the opening timing is too late, it can cause problems such as stretching, uneven seams or bird’s nests at the sewing start, depending on the type of material. LH4-B800E 4 - 20...
  • Page 108 If the feed mechanism is moved when the lower thread trimming has been carried out, the mechanisms will press against each other, which may result in damage to the lower thread clamp t and the opening plate r. LH4-B800E 4 - 21...
  • Page 109 1. Loosen the screws q, and then adjust so that the distance between the lower thread clamp t and the lower thread presser y is approximately 5 mm when the feed guide shaft w is projecting out at the front and is firmly touching the roller r of opening plate B e. LH4-B800E 4 - 22...
  • Page 110: Adjusting The Bobbin Presser

    If this timing is reversed, it will cause problems such as an excess trailing length of upper thread. LH4-B800E 4 - 23...
  • Page 111: Adjusting The Thread Breakage Detector

    When the thread guide r is moved to position (B) and then released, check that it moves smoothly back to position (A). If it does not move smoothly, check that the clearance between the thread breakage detection lever e and the arm is 0.1—0.5 mm. LH4-B800E 4 - 24...
  • Page 112: Adjusting The Thread Tension At The Tack Tension Control

    1. Loosen the screw q, and then move the tension stud bracket assembly w in and out to adjust so that the tension disc opening amount is 0.5—1.0 mm. Check that the tension discs are fully closed when the power is turned off. LH4-B800E 4 - 25...
  • Page 113: Adjusting The Upper Thread Feeding Amount

    If you do not have a spring gauge, loosen the three screws w and adjust using the adjustment bolt q. Adjust the tension so that the amount of belt deflection is approximately 3.5 mm when a force of 5 N is applied in the middle of the belt span. LH4-B800E 4 - 26...
  • Page 114: Adjusting The Upper Shaft Timing Belt

    If the lubrication amount has been reduced, run the machine for 200—300 sewing cycles and then check it again. If lubrication stops, it will cause problems such as rotary hook seizure and thread breakages. LH4-B800E 4 - 27...
  • Page 115: Adjusting The Needle Up Stop Position

    An abnormal noise may be heard due to the V-belt slipping; or e. The V-belt may become too loose and contact the cover. If any such problems occur, adjust by following the procedure described above. LH4-B800E 4 - 28...
  • Page 116: Troubleshooting Guide

    Purl stitch 0.05 - 0.15N (Holding the thread steady, the bobbin case should gently descend under the force of its own weight) Main thread tension Adjust the needle Adjust it while checking stitches (Instruction) thread tension LH4-B800E 5 - 1...
  • Page 117 Adjust the center of screw to the thread take position guide position carved mark Carved mark Gap 0.5 mm Bobbin case Damaged outside of Polish with buff Use the B800E bobbin case. bobbin case Replace the part Bent bobbin holder spring, etc. LH4-B800E 5 - 2...
  • Page 118: Skipped Stitches

    Replace with short Process the work clamp assembly 4-16 means that material is work clamp that to match the joint section. not being clamped. matches the sewing (Attach or remove rubber.) length. Use the accessory auxiliary sheet. LH4-B800E 5 - 3...
  • Page 119: Uneven Seams 1)

    35 - 40 mm thread leader is left after trimming 35 - 40 mm Bobbin presser Adjust the bobbin 4-23 position presser. Bobbin insertion Insert the bobbin (Instruction) correctly. Presser foot lifting Reduce the setting for (Instruction) speed memory switch No. 02. LH4-B800E 5 - 4...
  • Page 120 Bird's nests form at the sewing start, and after 5 -- 6 mm the sewing pitch suddenly increases. Cause Check Solution page Lower thread Lower thread clamp Adjust the opening Advance the timing at which the 4-20 clamp timing timing of the lower lower thread clamp starts to open. thread clamp. LH4-B800E 5 - 5...
  • Page 121: Uneven Seams 2)

    Needle plate Needle plate When using knit Using the thin -5 needle plate and material, replace with flat work clamp can be effective. the -3 needle plate. Replace with a needle plate with a 1.2 needle hole. LH4-B800E 5 - 6...
  • Page 122: Uneven Seams 5)

    Move it down in case (B) adjust its position Bobbin Bobbin thread tension Adjust the bobbin (Instruction) thread thread tension Bobbin case Refer to "5-1. Needle thread breakage" Stitch Purl stitch, Whip stitch Parameter No. 11 (Instruction) patterns setting LH4-B800E 5 - 7...
  • Page 123: Needle Thread Runout

    Zigzag tension Tack tension Upper thread Needle thread take-up Increase needle thread Increase thread take up to a degree 4-26 feeding take-up that needle thread does not take off upper thread trimmer assembly Screw More Less LH4-B800E 5 - 8...
  • Page 124 Bar tack Bar tack thread tension Adjust so that whip (Instruction) thread is too strong. stitches are formed at tension the sewing start. Upper thread Upper thread breaks. Refer to "5-1. Needle thread breakage" breakage LH4-B800E 5 - 9...
  • Page 125: Unraveling Of Thread Trimmed By Upper Thread Trimmer Assembly

    Upper thread trimmer driving spring Trimmer Upper thread scissors Adjust the position of Adjust the upper thread scissors 4-15 driving arm cutting depth the trimmer driving arm cutting depth. (clearance between roller. scissors assembly and presser roller bracket) LH4-B800E 5 - 10...
  • Page 126: Needle Strikes Upper Thread Trimmer

    5.5 -- 6 mm at this time. Upper thread Upper thread trimmer The upper thread trimmer lever lever operating force trimmer lever should gently open when the stop plate is separated from the stopper. LH4-B800E 5 - 11...
  • Page 127: Needle Breakage

    0.3 mm needle bar and cutter the clearance between the needle bar and the O.K. cutter is 0.3 mm. The cutter release section of the needle bar should be at a right angle to the cutter. LH4-B800E 5 - 12...
  • Page 128: 1)imperfect Cutter Function (imperfect Material Cutting)

    Is the cam opening the If the feed mechanism 4-18 scissors stop plate? operates when the cam has not opened the O.K. stop plate, the cutter will bump against the upper thread scissors. Adjust the cam position. LH4-B800E 5 - 13...
  • Page 129: Needle Thread Mis-winding

    Upper clamping foot assembly (for knits) Needle plate 1.2 (subclass -3) Underlay Underlay sewing Reduce the setting for (Instruction) the sewing start pitch for underlay sewing (parameter No. 52) to around 0.5. Reduce the underlay sewing speed (parameter No. 48). LH4-B800E 5 - 14...
  • Page 130: Folding Clamp Is Not Raised (1) Pulse Motor Stepping Sound Cannot Be Heard

    (Instruction) height setting height setting. memory switch Nos. 04., 05. and 06.. Presser foot Cord connection Check the cord lifter pulse connections and motor contacts. Presser lifter pulse Check for loose gear motor gear set screw. LH4-B800E 5 - 15...
  • Page 131 (memory switch No. 02.) to reduce the lifting speed. Presser foot Presser foot lifter home Adjust the presser foot lifter home position sensor lifter home position position position sensor position. sensor LH4-B800E 5 - 16...
  • Page 132: Lower Thread Is Not Trimmed (pulls When Material Is Removed)

    Adjust the cam position. Feed home Feed home position Adjust the feed home position sensor position position sensor sensor position. Feed timming Feed timing belt Adjust the feed timing 4-26 belt tension belt. LH4-B800E 5 - 17...
  • Page 133: Needle Does Not Zigzag Or Noise Occurs When Needle Zigzags

    If the treadle is pressed firmly and (Instruction) stop A-3 is set to ON, an then released, the treadle may be emergency stop occurs judged to have been depressed when the treadle is backwards and an emergency stop depressed. may occur. LH4-B800E 5 - 18...
  • Page 134: Electric Mechanism

    While the power is turned on, the cooling fan of the control box operates; be careful not to get caught in it. When separating or rejoining connectors, and measuring something, be careful not to cut your fingers on metal parts such as heatsinks and covers. LH4-B800E 6 - 1...
  • Page 135: Components Inside The Control Box And The Operation Panel

    Auxiliary circuit board (rear) Fan 1 (circulation) Panel PCB Fan 2 (ventilation) 2-step power supply circuit board 1-step power supply Transformer circuit board Air inlet Main circuit board Operation panel Control box 6 - 2 LH4-B800E...
  • Page 136: Fuse Explanation

    * F2 may also blow as a result of a malfunction of the peripheral electronic component FET. Open the cover. The fuses are mounted to the circuit boards as shown. 1-step power supply Main circuit board 2-step power supply circuit board circuit board LH4-B800E 6 - 3...
  • Page 137: Connectors

    Connector positions Main circuit board OPSOL AC17/AC30V DC300V FAN2 SYNC EXPAND1 AC18V PANEL EXPAND2 FAN12 PEDAL HEAD POWER HPEDAL Sub circuit board FAN1 VALV FAN2 OPSEN1 EXP1 OPSEN2 EXP2 OPSEN1 CUTTER POWER FTPM FDPM 6 - 4 LH4-B800E...
  • Page 138 6. ELECTRIC MECHANISM 1-step power supply circuit board 2-step power supply circuit board POWER ACIN Panel PCB PANEL LH4-B800E 6 - 5...
  • Page 139 One of error E-02, E-62, E-63 and E-64 is displayed. Needle up stop position signal Needle down stop position signal P4 [PANEL] Pin No. Signal name Symptoms resulting mainly from poor contact The panel does not operate. KEY0 KEY1 KEY2 SENSOR BUZZER 6 - 6 LH4-B800E...
  • Page 140 The home position can not be found. The presser foot does not operate. FORSW signal The machine does not operate. One of error E-30, E-31 and E-32 is displayed. BAKSW signal INCHSW signal PRSW signal HPEDAL signal LH4-B800E 6 - 7...
  • Page 141 +24V Feed home position signal +24V Presser foot home position signal P13 [FAN12] Pin No. Signal name Symptoms resulting mainly from poor contact +24V The exhaust fan does not operate. Error E-42 is displayed. FAN1 signal 6 - 8 LH4-B800E...
  • Page 142 AC18V (F) AC18V (F) P15 [DC300V] Pin No. Signal name Symptoms resulting mainly from poor contact DC300V The zigzag home position can not be found. The zigzag mechanism does not operate. DC0V Error E-05 is displayed. LH4-B800E 6 - 9...
  • Page 143 Pin No. Signal name Symptoms resulting mainly from poor contact AC30V The tension release solenoid does not operate. The control box fan does not operate. AC30V One of error E-41 and E-42 is displayed. AC17V AC17V 6 - 10 LH4-B800E...
  • Page 144 Presser foot PM direction signal Feed PM direction signal Presser foot PM current control signal Feed PM current control signal PM current OFF signal VALV1 VALV2 VALV3 VALV4 VALV5 VALV6 +55V OFF signal +55V relay output signal LH4-B800E 6 - 11...
  • Page 145 Cutter home position sensor signal Feed PM overcurrent signal Presser foot PM overcurrent signal +55V relay input signal +55V voltage watch signal Cutter return signal Cutter signal Cutter signal Spare solenoid 1 Spare solenoid 2 Spare solenoid 3 6 - 12 LH4-B800E...
  • Page 146 Presser foot PM direction signal Feed PM direction signal Presser foot PM current control signal Feed PM current control signal PM current OFF signal VALV1 VALV2 VALV3 VALV4 VALV5 VALV6 +55V OFF signal +55V relay output signal LH4-B800E 6 - 13...
  • Page 147 The presser foot home position can not be found. The presser foot mechanism does not operate. Presser foot PM driving current B Error E-07 is displayed. Presser foot PM driving current C Presser foot PM driving current D Presser foot PM driving current F 6 - 14 LH4-B800E...
  • Page 148 Cutter home position sensor signal P8 [CUTTER] Pin No. Signal name Symptoms resulting mainly from poor contact Cutter driving current The cutter does not operate. Error E-08 is displayed. Cutter return driving current Cutter driving current Cutter return driving current LH4-B800E 6 - 15...
  • Page 149 Special edition +55V +55V Spare solenoid driving current 7 Spare solenoid driving current 8 Spare solenoid driving current 9 P12 [FAN2] Pin No. Signal name Symptoms resulting mainly from poor contact +24V Special edition Spare input 6 - 16 LH4-B800E...
  • Page 150 Cutter home position sensor signal Feed PM overcurrent signal Presser foot PM overcurrent signal +55V relay input signal +55V voltage watch signal Cutter return signal Cutter signal Cutter signal Spare solenoid 1 Spare solenoid 2 Spare solenoid 3 LH4-B800E 6 - 17...
  • Page 151 Pin No. Signal name Symptoms resulting mainly from poor contact AC230/240-R The zigzag home position can not be found. The zigzag mechanism does not operate. Error E-05 is displayed. The tension release solenoid does not operate. AC230/240-T 6 - 18 LH4-B800E...
  • Page 152 The zigzag home position can not be found. The zigzag mechanism does not operate. DC0V Error E-05 is displayed. Pin No. Signal name Symptoms resulting mainly from poor contact Resistance Voltage error occurs. Error E-95 is displayed. Resistance LH4-B800E 6 - 19...
  • Page 153 Symptoms resulting mainly from poor contact ACIN The feed home position and presser foot home position can not be found. ACIN The feed mechanism and presser foot mechanism do not operate. One of error E-06 and E-07 is displayed. EARTH 6 - 20 LH4-B800E...
  • Page 154 6. ELECTRIC MECHANISM <Panel PCB> P1 [PANEL] Pin No. Signal name Symptoms resulting mainly from poor contact The panel does not operate. KEY0 KEY1 KEY2 SENSOR BUZZER LH4-B800E 6 - 21...
  • Page 155: Description Of Dip Switches

    2-cycle sewing ON (All programs will be set to 2-cycle sewing regardless of the setting for parameter No. 55.) 2-cycle sewing OFF Upper thread breakage detection disabled Upper thread breakage detection enabled Programs disabled Programs enabled 6 - 22 LH4-B800E...
  • Page 156 * If the programs are initialized when Nos. 3, 4 and 5 are set to OFF, OFF and ON (work clamp size 5.4 x 19 mm [4.0 x 15 mm]) respectively, the initial value for parameter No. 02 - Cutter size will be set to 6.0. LH4-B800E 6 - 23...
  • Page 157 DIPSW1 Setting item Default Three warning beeps Continuous warning beep Needle feed motor excitation turned off during emergency stop and thread breakage Needle feed motor excitation not turned off during emergency stop and thread breakage 6 - 24 LH4-B800E...
  • Page 158 Pedal: for seated operation Starting possible only when presser foot is lowered Starting possible regardless of presser foot position ON, ON ON, OFF 4, 5 OFF, OFF OFF, ON OFF, OFF 100V, 110V specifications OFF/ON 200V, 400V specifications LH4-B800E 6 - 25...
  • Page 159: Description Of Machine Motor Parameters

    - When the ENTER key is pressed, the value appearing in the parameter display LED is accepted (the display stops flashing). - When the motor select key is pressed, machine motor parameter setting mode will then end and the sewing machine will start up normally. 6 - 26 LH4-B800E...
  • Page 160: Error Code Table

    E-52 Y pitch error Turn off the power. E-54 Overall cycle program stitch no. error Exceeds 3,000 stitches. Clear the cycle program and reset automatically. E-55 Stitch no. error Exceeds 700 stitches. Turn off the power. LH4-B800E 6 - 27...
  • Page 161 2. Reduce the setting value for parameter 04 (Zigzag pitch). Increase the setting for parameter 03 (Zigzag stitch [multi-working knife]). 3. Press the SELECT key to change to automatic mode. If "C-Er" is still displayed, repeat steps 1. to 3. 6 - 28 LH4-B800E...
  • Page 162: Troubleshooting

    * If the result of continuity test is not acceptable in either case, replace the feed home position sensor. 3. If there is still an error even after replacing the feed home position sensor, replace the main circuit board. LH4-B800E 6 - 29...
  • Page 163 * OK if 17 V AC is present between pins 4 and 5 of connector P20 on the main circuit board. If not OK, replace the transformer. 4. Replace the cooling fan. 5. Replace the main circuit board. 6 - 30 LH4-B800E...
  • Page 164 2. If error E-55 appears again after the above operation is carried out, turn off the power and initialize the settings. 1. Turn off the power and initialize the settings. E-59 2. If error E-59 appears again after the above operation is carried out, replace the man circuit board. LH4-B800E 6 - 31...
  • Page 165 4. Replace the 1-step power supply circuit board. 5. Replace the main circuit board. 1. Check fuse F1 on the main circuit board. E-93 2. If fuse F1 on the main circuit board is blown, replace it. 6 - 32 LH4-B800E...
  • Page 166 1-step power supply circuit board are securely inserted and if any harness is broken or short-circuited. 5. Replace the 1-step power supply circuit board. 6. Replace the main circuit board. ArEA Refer to "6-7. Error code table". C-Er Refer to "6-7. Error code table". LH4-B800E 6 - 33...
  • Page 167: Control Circuit Block Diagram

    B3B-PH-K-S B4B-XHA B4B-PH-K-S B3B-PH-K-S PHR-3 PHR-4 PHR-3 Green/Yellow ACIN(R) Black ACIN(T) White EARTH DC fan Power switch OUT220V DC fan White White Conversion transformer Black Black Treadle unit Green/Yellow Green/Yellow Power supply plug Machine motor IN240,380,400,415V LH4-B800E 6 - 34...
  • Page 168 SERVICE MANUAL BROTHER INDUSTRIES, LTD. 15-1, Naeshiro-cho, Mizuho-ku, Nagoya 467-8561, Japan. Phone: 81-52-824-2177 Printed in Japan 118-H80 I1050811H 2001.07. H (1)

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