Baby Lock BL7800 Service Manual Download Page 5

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POWER TRANSMISSION CHART

(A)

Generating mechanism of needle bar, thread take-up lever and zigzag movements

(B)

Mechanism of feed dog and rotary hook movement

Upper shaft

Balance wheel

ZPM

(Zigzag pulse motor)

Needle bar crank rod

Needle bar clamp

Needle bar supporter

Zigzag connecting rod

Needle bar

Needle

Balance wheel

Upper shaft

Horizontal cam pulley

Timing belt

FPM

(Feed pulse motor)

Timing pulley D

Vertical feed cam

Rotary hook assembly

Feed stand

Feed dog Drop plate

Lower shaft

Side feed plate spring

Horizontal feed arm

Lower shaft gear

Horizontal feed plate

Horizontal feed shaft

Side feed plate

Summary of Contents for BL7800

Page 1: ...4 2001...

Page 2: ...ING THE SEWING MACHINE 7 III HOW TO ADJUST MECHANICAL ELEMENTS 20 IV HOW TO ADJUST ELECTRONIC ELEMENTS 37 1 Always use rubber gloves when handling printed circuit boards and never touch the metal port...

Page 3: ...MECHANICAL CHART 2 2 POWER TRANSMISSION CHART 3 3 ELECTRONIC PARTS ARRANGEMENT CHART 4 4 CONTROL SYSTEM BLOCK DIAGRAM 5 5 MOTOR UNIT CONTROL 5 6 PATTERN GENERATOR 5 7 OTHER ELECTRONIC COMPONENT FUNCTI...

Page 4: ...2 1 MECHANICAL CHART...

Page 5: ...otor Needle bar crank rod Needle bar clamp Needle bar supporter Zigzag connecting rod Needle bar Needle Balance wheel Upper shaft Horizontal cam pulley Timing belt FPM Feed pulse motor Timing pulley D...

Page 6: ...ch SS start stop PC board ZPM zigzag pulse motor BH buttonhole switch BHL buttonhole lever switch WB light Lamp VR PC board Power supply unit Main PC board Inlet assembly FC foot controller jack Power...

Page 7: ...a had been mechanically engraved In contrast to this this model stores the data electronically in memory and uses a feed pulse motor and a zigzag pulse motor to directly rock the needle bar and the fe...

Page 8: ...Buttonhole stitch lever BHL switch used to detect whether the buttonhole stitch lever is raised or lowered Needle position NP sensor detects the drive timing of zigzag and feed pulse motors and detect...

Page 9: ...7 1 DISASSEMBLING AND REASSEMBLING THE OUTER PARTS AND MAIN PARTS 8 2 LEAD WIRE ARRANGEMENT 19...

Page 10: ...on face plate side below free arm Open the front cover toward the front remove the three connectors and then the front cover 6 Remove the two screws securing the needle plate and the needle plate 7 R...

Page 11: ...holder 17 Remove the two springs and the needle bar supporter assembly 18 Remove the two screws and the ZPM assembly Disassembly Points 9 To disconnect the connectors grab the base of the connector a...

Page 12: ...21 Remove the presser bar clamp screw 22 Remove the presser bar by lifting it from above and the presser bar clamp 23 Remove the presser spring screw and the presser bar spring 24 Remove the presser l...

Page 13: ...and the outer rotary hook assembly 34 Remove the two metal presser screws and remove the lower shaft assembly and timing belt 35 Remove the connector the two screws and the power supply unit assembly...

Page 14: ...ting direction clearance of the outer rotary hook by adjusting the position of the hole in the eccentric metal Moving the hole downward decreases the play Although the ideal position is facing forward...

Page 15: ...13...

Page 16: ...ight and left clearance may generate an irregular noise thread take up lever noise 55 Install the inner rotary hook bracket assembly Firmly tighten the screw to make no space between C and the arm bed...

Page 17: ...15...

Page 18: ...alling the needle bar supporter assembly insert it into the needle bar crank rod insert the needle bar supporter stud then install the two springs Hook the longer end of the spring E to the arm bed 59...

Page 19: ...17...

Page 20: ...nd fit the blind cap on 73 Attach the free arm cover using the screw 74 Attach the face plate using the screw Assembly Points 68 When installing the rear cover lower the presser foot lifter slightly l...

Page 21: ...19 2 LEAD WIRE ARRANGEMENT...

Page 22: ...D DOG 27 9 PRESSER BAR HEIGHT 28 10 POSITION OF BUTTONHOLE SWITCH LEVER 29 11 BOBBIN WINDER 30 12 DIAL TENSION 31 13 UPPER THREAD TENSION 31 14 INNER ROTARY HOOK BRACKET POSITION 32 15 INNER ROTARY HO...

Page 23: ...ding pattern key The monitor sign LED will blink Test Mode No Pattern Key Adjustment Items Page 1 Needle down position adjustment left base line Timing of needle and rotary hook Needle bar height 23 2...

Page 24: ...ing the motor holder 2 Adjust the belt tension by moving the motor holder 3 Tighten the two screws Adjustment Points 1 If the timing belt tension is too loose the belt may jump while sewing on denim a...

Page 25: ...on ADJUSTMENT 1 Put the machine in test mode 2 Turn the balance wheel to move the needle to the needle down position 3 Loosen the screw securing the zigzag adjusting nut 4 Turn the balance wheel to mo...

Page 26: ...less and they should never touch each other ADJUSTMENT 1 Put the machine in test mode and select pattern 2 Loosen the three screws of the lower shaft gear 3 Adjust the clearance between the needle and...

Page 27: ...of the needle bar crank rod assembly 4 Move the needle bar vertically to adjust the clearance to between 1 0 1 4 mm 5 Tighten the screw of the needle bar crank rod assembly NOTE The needle clamp shou...

Page 28: ...e clearance between the feed dogs and needle plate at the feed start position when feed dogs are at very front should be 0 5 to 1 0 mm refer to illustration ADJUSTMENT 1 Put the machine in test mode a...

Page 29: ...eed roller shaft 3 Turn the vertical feed roller shaft to adjust the feed dog height to within 0 9 1 1 mm 4 Tighten the screw securing the vertical feed roller shaft Adjustment Points 1 If the feed do...

Page 30: ...of the presser bar guide bracket NOTE The presser foot should be parallel to the feed dog hole of the needle plate Refer to A Adjustment Points 1 Install presser foot J 2 When adjusting the presser b...

Page 31: ...lower the presser foot lever 3 Adjust the position of buttonhole lever so that BH0 touches BH1 when the buttonhole eccentric shaft C is rotated NOTE In case that the legs are shorter than the standar...

Page 32: ...ertically C 3 Tighten the bobbin winding guide screw 4 Loosen the screw securing the bobbin presser slightly 5 Turn the bobbin presser to adjust the bobbin thread amount 6 Tighten the screw of the bob...

Page 33: ...it is between 33 and 38 g 4 Tighten the adjusting screw on the thread tension regulating nut 13 UPPER THREAD TENSION STANDARD With the presser foot lowered and the thread tension dial set to 4 use po...

Page 34: ...k bracket should be perpendicular to the feeding direction 3 Tighten the screw of the inner rotary hook bracket 15 INNER ROTARY HOOK TENSION STANDARD While slowly pulling polyester thread 60 using a t...

Page 35: ...orward and 100 stitches from the back will meet ADJUSTMENT 1 Loosen the screw securing the pulse motor 2 Rotate the pulse motor and adjust the pattern Make sure not to contact the main PC board during...

Page 36: ...r may be broken rendering it unusable Besides this it may cause the needle to break which could result in injury 7 If a 9 needle is used the variation in needle precision may result in the needle bein...

Page 37: ...up so that the guide is fits into the groove 20 NEEDLE THREADER CHECKING THE HOOK IN STANDARD POSITION STANDARD 1 The clearance between the top of hook and the top of needle eye is 0 mm 2 Threading i...

Page 38: ...screw If a and b are not parallel the needle threader will not be held by the needle threader position setter refer to Fig 1 the hook will not enter the eyelet of the needle hook will not move and th...

Page 39: ...not stable maximum speed operation is not possible or speed cannot be adjusted 39 6 Correct patterns are not created 39 7 Buttonholes are not stitched correctly 39 8 Manual operation of feed and zigza...

Page 40: ...Zigzag CN1 1 3 2 4 8 to 10 Feed CN2 1 3 2 4 8 to 10 2 Set the home position for the same pulse motors irrespective of needle position 3 Is a fuse blown 4 Is the voltage between pins 4 5 normal when t...

Page 41: ...to 5 V 4 Others 1 Adjust the installation position so that it moves easily 2 Replace the malfunctioning pulse motor or the lead wire assembly 3 Replace the NP PC board assembly 4 Replace the main PC...

Page 42: ...he dial tension correct 5 Is the rotary hook tension correct 6 Is the gap in the thread tension device correct 1 Check 2 Check 3 Check see page 36 4 Adjust the dial tension and upper thread tension se...

Page 43: ...41 Main PC board...

Page 44: ...42 Power supply unit Power 120 Power 230...

Page 45: ...43 Operation board Other PC boards...

Page 46: ...BL7800 T1010141...

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Baby Lock BL7800, Service Manual

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