Cause Of Troubles And Troubleshooting; Sewing Machine Troubleshooting - SunStar KM-1060BL User Manual

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Cause of troubles and troubleshooting

1) Sewing machine troubleshooting

No Symptom
Direction and height of needle
Needle
1 Needle breaks
Ascending level of needle bar
Height of needle
Gap between needle and hook
Threading method
Needle
Direction and height of needle
2 Thread breaks
Upper thread tension
Lower thread tension
Worki n g capaci t y of take-up l e ver spri n g
Direction and height of needle
Needle
Threading
Ascending level of needle bar
Height of needle bar
Gap between needle and hook Wrong timing of needle and hook
3 Stitch skips
Racing-proof spring of
bobbin case
Take-up lever spring
38
Checkpoints
Needle is inserted into wrong position
Needle is bent
Bad timing of feed dog
Bad timing of needle and hook
Bad timing of needle and hook
Bad timing of needle and hook
Wrong threading
Bent needle or broken needle tip
Needle inserted in the wrong position
Too tight upper thread tension
Too loose lower thread tension
Loose upper thread
Needle inserted into wrong position
Bent needle or broken needle tip
Thread passing at wrong position
Wrong timing of needle and hook
Wrong timing of needle and hook
Remaining length of upper thread is short
Due to bobbin racing during trimming, lower
thread dropping from bobbin case becomes
too short to go up
Unable to lift lower thread due to weak take-
up lever spring
Root cause
Reinsert the needle correctly
Change the needle
Adjust the timing of feed dog
Adjust the timing of needle and hook
Adjust the timing of needle and hook
Adjust the timing of needle and hook
Thread the needle correctly
Change the needle
Insert the needle correctly
Reduce tension of upper thread
Reduce tension of lower thread
Adjust take-up lever spring
Reinsert the needle in the right direction
Change the needle
Change the needle
Adjust the timing of needle and hook
Adjust the timing of needle and hook
Adjust the timing of needle and hook
Adjust the thread adjusting device
Change the racing protection spring
Adjust the working capacity of take-up lever
spring
Corrective action