Summary of 8050
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Service manual parts list 8050
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Index what to do when................................................................................................................................ 1 - 3 changing external parts face cover ................................................................................................................
Page 3: What to Do When
1 condition cause how to fix reference 1. Skipping stitches 1. Needle is not inserted properly. 2. Needle is bent or worn. 3. Incorrectly threaded. 4. Needle or thread are inappropriate for the fabric being sewn. 5. Sewing on stretch fabric. 6. Inappropriate needle bar height. 7. Inappropriate needl...
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2 condition cause how to fix reference 3. Breaking upper thread. 1. Initial sewing speed is too fast. 2. Thread path is incorrect. 3. Needle is bent or dull. 4. Top tension is too strong. 5. Needle size is inappropriate for fabric. 6. Needle eye is worn. 7. Needle hole in needle plate is worn or bur...
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3 condition cause how to fix reference 6. Noisy operation 1. Backlash between hook gear and lower shaft gear is too great. 2. Lower shaft gear is loose. 3. Inappropriate belt tension. 4. Not enough oil. 5. Upper shaft gear is loose. 6. Hook is broken or too worn. Eliminate the backlash. Eliminate th...
Page 6: Changing External Parts
4 changing external parts face cover to remove: 1. Loosen the setscrew q and lift the face cover to disengage the rib on the inside. Remove the face cover w. To attach: 2. Follow the above procedures in reverse. Q w.
Page 7: Changing External Parts
5 free-arm cover to remove: 1. Loosen the setscrew q and w. Move the free-arm cover e to the left. Remove the free-arm cover. To attach: follow the above procedures in reverse. Changing external parts q w e.
Page 8: Changing External Parts
6 changing external parts front cover (1) to remove: 1. Remove the face cover and free-arm cover (see page 8 and 9). 2. Remove the setscrews (a) q (2 pcs.). 3. Remove the setscrews (b) w (5 pcs.), back cover e. 4. Remove the setscrews (c) r (2 pcs.). 5. Loosen the setscrew t. 6. Disconnect all the c...
Page 9: Changing External Parts
7 changing external parts front cover (2) 1. Disengage the front cover and rear cover hooks. 2. Remove the front cover. To attach: follow the above procedures in reverse..
Page 10: Changing External Parts
8 changing external parts rear cover to remove: 1. Remove the face cover and free-arm cover (see page 4 and 5). 2. Remove the setscrews (a) q (4 pcs.). 3. Remove the setscrews (b) w (5 pcs.) and back cover. 4. Remove the setscrews (c) e (2 pcs.). Remove the rear cover. To attach: 5. Follow the above...
Page 11: Mechanical Adjustment
9 6.0 mm mechanical adjustment presser bar height the distance between the bottom of the presser foot in up position and the needle plate should be 6.0 mm. 1. Remove the face plate and needle. 2. Lower the feed dog below the needle plate. Place a block 6 mm thick under the presser foot and lower the...
Page 12: Mechanical Adjustment
10 0.2 mm or more 0.2 mm or more a = b mechanical adjustment needle drop position set the stitch pattern to “ ”. The standard needle drop position should be at cen- ter of the needle plate hole q. Select zigzag stitch “ ”, and set the stitch width at “5.0”. The clearance between the needle and the e...
Page 13: Mechanical Adjustment
11 the amount of ascending travel of the needle bar from its lowest position to the position ( ) where the tip of the rotary hook exactly meets the right side of the needle should be 3.25 to 3.55 mm. 1. Remove the needle plate and bobbin holder. 2. Turn the power switch on. 3. Select the pattern (le...
Page 14: Mechanical Adjustment
12 replacing hook if the hook point is damaged or too worn, the hook needs to be replaced. To remove: 1. Remove the needle plate and bobbin holder. 2. Remove the front cover (see page 6 and 7). 3. Turn the handwheel toward you to align the hook point and the right edge of feed dog teeth. 4. Mark bot...
Page 15: Mechanical Adjustment
13 before proceeding with this adjustment, check the hook timing (refer to page 11). The distance between the upper edge of the needle eye and the tip of the hook should be in the range of 1.6 to 2.0 mm when the tip of the hook timing meets right side of the needle in the left needle position ( ) as...
Page 16: Mechanical Adjustment
14 adjustment procedure: 1. Remove the needle plate and bobbin holder. Attach the master needle. Turn the power switch on and set the zigzag width at maximum. 2. Remove the face cover. 3. Loosen the setscrew a (2 pcs.). 4. Turn the handwheel toward you. Adjust the clearance between the needle and th...
Page 17: Mechanical Adjustment
15 the highest position of the feed dog should be between 0.80 and 0.90 mm from the surface of the needle plate. 1. Lower the presser foot and turn the power switch on. 2. Turn the handwheel toward you to set the feed dog at the highest position. 3. Remove the free-arm cover. 4. Loosen the setscrew ...
Page 18: Mechanical Adjustment
16 mechanical adjustment top tension the top tension should be between 65 and 80g when pulling the thread up in the direction of arrow. * use polyester sewing thread #50 (white). * if it is not within the above limit, adjust as follows. 1. Set the tension dial “4”. 2. Remove the cover. 3. Lower the ...
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17 circuit board-a connection note: do not disconnect the connectors by pulling on cord. To disconnect, grasp the connector, not the cord. Replacing the electronic components r y u i o !0 !1 !2 printed circuit board a printed circuit board f printed circuit board l q printed circuit board p (black) ...
Page 20: Self-Diagnostic Test
18 to enter self-diagnostic mode: preparation: 1. Turn the power switch off. 2. Move the bobbin winder spindle to the left. 3. Raise the feed dog. 4. Set the speed control lever to the left. 5. Remove the presser foot and raise the presser foot lifter. 6. Turn the hand wheel toward you to raise the ...
Page 21: Self-Diagnostic Test
19 correct condition sewing lamp and lcd backlight lit. Lcd displays “01”. 01) function of lcd, buzzer and lamp procedure turn on the power switch while simultaneously press- ing the start/stop button and locking stitch button. Press the start/stop button. If the result is correct con- dition, press...
Page 22: Self-Diagnostic Test
20 correct condition step and items to check 05) not applicable for this model procedure defective condition turn the handwheel toward you. Lower the needle bar from its highest to its lowest position. Raise the needle bar from its lowest position to its highest position. If the result is correct co...
Page 23: Self-Diagnostic Test
21 correct condition lcd displays “sc 08”. Step and items to check 08) foot control procedure attach the foot control to the sewing machine. Depress the foot control as far as it goes, then release it. If the result is correct condition, press the start/stop button to proceed the next step. If the r...
Page 24: Self-Diagnostic Test
22 self-diagnostic test buzzer sounds after few seconds when the self-diagnostic test has been finished. The test result has been determined. Correct: buzzer sounds and lcd displays “00” defective: caution buzzer sounds and lcd displays the defective part number. Refer to page 19-21 and fix the defe...
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23 circuit board-a (1) to remove: 1. Remove the front cover. (see pages 6 – 7) 2. Pull out connectors from the circuit board-a. 3. Remove the screws (6pcs.) and the circuit board-a. To attach: 1. Follow the above procedures in reverse. Note: do not disconnect the connectors by pulling on cord. To di...
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24 circuit board-a(2) setting the circuit board a replacing the electronic components after install the circuit board a, select the appropriate setting of the circuit board a. 1. Turn the power switch on while simultaneously pressing left cursor button “ ” and the right cursor “ ” button. 2. After t...
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25 driving motor to remove: 1. Remove the front cover. 2. Remove the setscrews (2pcs.) and the driving motor and the belt. To attach: 1. Install the driving motor and the motor belt. Tighten them with setscrews (2pcs.) lightly. 2. Move the motor up or down to adjust the motor belt tension. The belt ...
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26 switching regulator unit to remove: 1. Remove the front cover and the rear cover. 2. Remove the setscrews a (3 pcs.) and the switching regulator. 3. Remove the setscrews b (4 pcs.). To attach: 4. Follow the above procedures in reverse. Replacing the electronic components switching regulator setsc...
Page 29: Mechanical Adjustment
27 bh sensor 1.6 mm gap to enter adjusting mode mechanical adjustment adjusting buttonhole lever position to adjust the buttonhole lever guide: 1. Enter the buttonhole sensor adjusting mode. (see below. The lcd should display bh symbol.) 2. Remove the face cover (see page 4) and loosen the setscrew ...