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12.

DIAL TENSION

STANDAD

With the presser foot lowered and the thread tension dial set to "4", use polyester thread (#60) to check that the
tension between the tension discs is 33 to 38 g.

ADJUSTMENT

1.

Set the thread tension dial to "4", pass polyester thread (#60) between the tension discs, then lower the
presser foot.

2.

Loosen the adjusting screw on the thread tension regulating nut.

3.

Pull the thread with the tension gauge and turn the thread tension control screw to adjust the tension until 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 polyester thread (#60) to check that the
total tension of the tension plate and the tension discs is 44 to 54 g.

ADJUSTMENT

1.

After adjusting the dial tension, pass polyester thread (#60) between the tension plate and the tension discs,
then lower the presser foot.

2.

Pull the thread with the tension gauge and turn the thread tension control screw to adjust the tension until it is
between 44 and 54 g.

1

1

3

4

2

polyester

thread (#60)

33- 38g)

tension plate

tension discs

1

1

polyester thread (#60)

44-45g

Содержание BL7800

Страница 1: ...4 2001...

Страница 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...

Страница 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...

Страница 4: ...2 1 MECHANICAL CHART...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

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

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 15: ...13...

Страница 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...

Страница 17: ...15...

Страница 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...

Страница 19: ...17...

Страница 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...

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

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 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...

Страница 43: ...41 Main PC board...

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

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

Страница 46: ...BL7800 T1010141...

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