Mitsubishi PLK-E1010, Technical Manual

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9. BAD SEWING CONDITION & ITS CAUSE AND REMEDY
[NOTE]
Please fix the troubles during the sewing machine operation with referring to the
following instructions.
Beside, if the trouble conditions are not coming under these classification, please
contact the sewing machine dealers nearby.
Bad condition Cause Remedy
Ref. page
& Item
Poor thread quality Use better quality thread ----
Tight upper thread tension Adjust thread tension 6-3
Strong thread take up spring
Adjust thread take up spring
properly
7-14
Upper thread is thicker than
needle size
Change needle to suitable size ----
Damages on shuttle hook or
driver
Change them new ones or grind
them with buffing wheel or grind
stone
----
Damages inside presser foot
needle hole
Change it new one or grind it with
buffing wheel
----
Needle touches with presser
foot needle hole
Move presser foot position 7-6-1(6)
Needle and shuttle hook are
not in proper timing
Adjust the timing 7-2
Slow down sewing speed 6-2(4)
Use silicon oil ----
1.
Upper thread
breakage
often happens
Thread melts with needle heat
Use needle cooler ----
Thread tension discs are not
opened at trimming
Adjust thread tension release 7-17
Thread take up spring swings
too much
Adjust thread take up spring’s
swing stroke
7-14
Upper thread is broken before
regular trimming
Adjust fixed knife and needle plate
position
7-12
Needle size is bigger than
thread size
Change needle to suitable size ----
Pre-tension is too tight Adjust pre-tension 7-16
Thread guide is in wrong
position
Adjust thread guide position
properly
7-5
Needle and shuttle hook are in
bad timing
Adjust the position properly 7-2
Adjust trimmer cam position 7-10
Adjust movable knife position 7-11
2.
Upper thread
is pulled out
from needle
Trimmer timing is not correct
Adjust synchronizer position 7-18
Too short bobbin thread by
bobbin spinning at trimming
Use non racing spring with bobbin ----
Bobbin thread tension is too
tight
Loosen bobbin thread tension
spring
6-3(1)
Decrease pre-tension 7-16
Adjust trimmer cam position 7-10
Adjust synchronizer position 7-18
Make thread take up swing stroke
smaller
7-13
Advance thread tension release
timing
Control
unit
3.
Skip stitch
happens at
start sewing
Thread tail from needle is very
short after trimming
Adjust thread guide position
properly
7-5
From the library of Superior Sewing Machine & Supply LLC • www.supsew.com