JUKI SC-320 - Needle Fails to Stop in down Position; Operation at Low Speed Fails to Stop; Stop at Position Other than the down Position

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Operation Trouble
What to check Repair
Pedal in
neutral
3-1 Needle fails to stop in down
position. ^
A) Operation at low speed
fails to stop.
B) Stop at position other
than the down position.
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(T) Does it stop after pedal
is depressed once?
Yes
(T) Is the stop position
different from the
up position?
Yes
No
Is the BR transistor circuit
board good?
(Check by replacing.)
Yes
No
Replace BR transistor circuit board.
No Does it stop temporarily and
then move to the up position?
1
Yes
r
Can thread be ti
rimmed?
Yes
Replace PSC box.
Pedal spring for depressing back part
of pedal is stiff. Adjust pedal sensor
angle or
VR8 (LSW).
Nol Replace control box.
No
Replace PSC box.
Recheck main circuit board function
selection switch.
Replace PSC box.
From the library of: Superior Sewing Machine & Supply LLC