Unicorn DB2-H515, Operation Manual

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P roblem Cau se Ch eck Solu tio n Page
Needle thread
es capes at st art
of sewi ng.
Tension disc does not
open sufficiently.
Tension disc
opening
Adjust tension release.
Excessive pretension ― Adjust pretension. 13
Needle too heavy for
thread
―
Use smaller size
needle.
Up needle stop position
too high, thread removed
by thread take-up. Thread take-up
height at up needle
stop position
Delay up needle stop
position timing.
Thread cutter
mechanis m does
not funct ion.
Thread cutter solenoid
dose not function.
Check with tester
Replace thread cutter
solenoid.
Thread cutter signal not
transmitted.
―
Check circuits; refer
to motor adjustment
manual
Thread wiper does
not funct ion.
Needle thread remainder
too long.
― Adjust pretension 13
Excessive material,
presser foot resistance
―
Replace with presser
foot having back
channel.
Timing too early; wipes
thread before tension
disc closes.
― Adjust timing.
Thread wiper operation
too short
― Adjust operation time.
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