JUKI LU-1508H - Trable of Troubles in Thread Trimming and Corrective Maesures

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10. TRABLE OF TROUBLES IN THREAD TRIMMING AND CORRECTIVE MAESURES
Troubles Causes Checking Corrective measures
1. One or several stitches
skip at the start of sewing.
Thread remaining at the
needle top after thread
trimming is short.
Bobbin thread is not
clamped.
Needle is too thick.
Needle hole in the feed dog
is too large.
Pressure of the presser foot
is too low.
Check the routing of
needle thread.
Thread tension given by
the tension controller No.
1 is too high.
Check the rising amount of
the thread tension disk No.
2 at the time of thread
trimming.
Thread trimming timing is
excessively advanced.
There are scratches on the
moving knife and the hook.
Position of the clamp
spring
Pressure of the clamp
spring is too low.
There are scratches on the
clamp spring.
Needle thread removes
bobbin thread.
Thread the needle thread
correctly.
Adjust so that abnormal thread
tensin is not applied to the
needle thread.
Decrease the tension given by
the tension controller No. 1.
Adjust so that the disk is raised
by means of the thread release
solenoid.
Refer to “Thread trimmer cam
timing” on page 31.
Polish with buff or replace the
part.
Refer to “Position of the counter
knife and the clamp spring” on
page 25.
Refer to “Position of the counter
knife and the clamp spring” on
page 25.
Replace the clamp spring with
a new one.
Increase or decrease the
tension of the tension controller
No. 1.
Replace the needle with a
thinner one.
Replace the feed dog with an
optional one with small needle
hole.
Increase the pressure of the
presser foot.