Troubleshooting; Upper Thread Breakage - Brother HE-800A Instruction Manual

１６. TROUBLESHOOTING
Turn off the power switch and disconnect the power cord before carrying out troubleshooting, otherwise
the machine may operate if the treadle is depressed by mistake, which could result in injury.
１６-１. Upper thread breakage
Cause
Needle
Threading
Thread path
Thread tension
Thread take-up
spring
Check
Needle facing
Needle installation height
Bent needle
Blunt needle tip or burr
Needle and thread
Upper thread threading
Lower thread threading
Flaw or abrasion on the
thread path
Flaw on the rotary hook
point and rotary hook
edge
Flaw on the rotary hook
holder
Zigzag thread upper
thread tension
Bar tack thread upper
thread tension
Thread take-up spring
tension and stroke
CAUTION
Remedy
As viewed from the direction of the face plate, attach
needle so that the notched part of needle faces
frontward.
Insert the end of the needle shank so that it touches
the top edge of the needle hole of the needle bar.
Replace needle
Replace needle
Replace needle that fits the thread
Thread the upper thread correctly.
Thread the lower thread correctly.
Polish with buff or replace the part.
Especially, pay attention to finishing around needle
plate hole.
Needle plate hole
Polish with buff or replace the part.
Polish with buff or replace the part.
Adjust the upper thread tension appropriately.
Adjust the upper thread tension while checking
stitches. (The stitches on top are the upper thread
and the stitches underneath are the bobbin thread.)
Loosen the thread take-up spring tension or shorten
the stroke to such a degree that does not cause
double hooking. Adjust it while checking bar tacking
stitches.
HE-800A

16. TROUBLESHOOTING

3996Q
Check flaw here
Adjust the rotary hook
overlap amount.
3997Q
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