Troubleshooting - Mitsubishi Electric PLK-G1010 Technical Manual

9. TROUBLESHOOTING

(1) Please make sure to turn the power switch off before adjusting the sewing machine.
(2) If the adjustment is required while the power switch on, do not step on the foot switch by mistake.
Condition
Upper thread is broken.
Bobbin thread is
broken.
Upper thread is pulled
from needle hole when
starting sewing.
Frequent skip stitching
happens.
Trimming is not
functioned.
CAUTION
Cause
Upper thread tension is too
tight.
Strength of thread take up
spring is inappropriate.
Parts on needle plate, hook,
and presser foot touching
thread are damaged.
The needle size is bigger
than the thread size.
Thread melts with heat.
Bobbin thread tension is too
tight.
Parts on needle plate and
presser foot touching thread
are damaged.
Thread tail is short.
Thread take up spring
tension is too much.
Clearance between needle
and shuttle hook is too big.
Timing of needle and shuttle
hook is not proper.
Contact between needle and
driver is too tight.
Needle is bent.
Needle is at wrong position.
Fixed knife is dull.
Movable knife is dull.
Corrective action
Adjust thread tension.
Adjust thread take up spring.
Grind parts or change parts.
Change the needle size to
suitable size.
Slow down the sewing speed
Use needle cooler.
Adjust thread tension.
Buff parts or change parts.
Adjust thread tail with
pre-tension.
Adjust thread take up spring
tension.
Adjust clearance between
needle and shuttle hook
properly.
Adjust position of needle and
shuttle properly.
Adjust clearance between
needle and driver properly.
Change needle.
Fix position properly.
Sharpen fixed knife or
change fixed knife.
Change movable knife.
- 30 -
Reference
6-3
7-17
-
-
6-1
-
6-3
-
7-18
7-17
7-3
7-2
7-4
-
5-2
7-16
7-15