JUKI AP-876/IP-420 Instruction Manual page 121

Phenomenon
4. The tread slps off the
needle upon beng
trmmed.
5. The needle thread
cannot be trmmed.
(The bobbn thread
can be trmmed.)
6. Bobbn thread cannot
be trmmed.
(Needle thread can be
trmmed.)
7. Nether the needle
thread nor the bobbn
thread can be trmmed.
8. Thread cannot be
trmmed sharply
9. The machne cannot
be powered on.
cause
1 The returnng force of the thread
take-up sprng s too hgh.
2 The tenson of the tenson controller
No.  s too hgh.
3 The counter knfe s mproperly pos-
toned.
1 The last sttch has been skpped.
(The clearance between the needle
and the hook s too large.)
1 The movng knfe fals to catch the
bobbn thread at the last sttch.
(The sttchng ptch of the last sttch
s excessvely large, and the bobbn
thread s not present on the movng
knfe locus.)
1 The thread trmmng tmng s wrong.
2 The knfe has been damaged.
3 The knfe pressure s nadequate.
4 The movng amount of the movng
knfe s too short.
5 Pattern nput falure
1 Thread trmmng tmng s wrong.
2 The knfe pressure s too low.
3 The knfe blade s blunt.
1 Emergency swtch s n the ON
state.
－
○ Refer to
spring"
○ Refer to
the counter knife and the knife
thread guide"
○ Refer to
adjustment"
○ Decrease the sttchng ptch of the
last sttch. (To approxmately 2
mm)
○ Replace the knfe.
○ Increase the knfe pressure.
○ It s necessary to check the thread
trmmng motor operaton.
○ Input the pattern pror to thread
trmmng usng the forward sttch.
○ Refer to
the counter knife and the knife
thread guide"
○ Increase the knfe pressure.
○ Replace the knfe.
○ Refer to
switch"
7
－
corrective measure
"!-4-7. thread take-up
p.20.
"#-1-4. Positioning
p.111.
"#-1-2. Needle and hook
p.109.
"#-1-4. Positioning
p.111.
"!-5. Emergency stop
p.24.