JUKI SC-320 - Thread Is Not Trimmed; Sewing Machine Fails to Stop in up Position; Continues to Run at Low Speed Without Stopping

I
-j
Operation Trouble
What to check
Repair
part of
pedal IS
depressed
4-1 Thread is not trimmed.
O Check for unplugged connector.
P49 (12?)
4-2 Sewingmachine fails to stop
in up position.
J1
A) Continues to run at low
speed without stopping.
CD Does the thread trimming solenoid fail to move?
Yes
Are the pedal stroke adjustment potentiometers (VR7 TSW)
correctly adjusted?
(When VR7 is turned counterclockwise" with the pedal in neutral
after the back part of pedal is depressed, thread trimmer is
actuated.)
'
Yes
r
@
Do the thread trimming solenoid resistance correct?
The resistance between P49 (12P) 10 and 11 should be about
7.5 Q.
1
Yes
r
©
Is a thread trimming signal being output?
Confirm that the monitor LED (TRM) on the main circuit board
light up.
Yes
(T) Is a brake signal being output?
Confirm that the main circuit board monitor LED (BR) is lit.
Yes
)
No
No.
No.
No.
Adjust or replace the thread trimmer
moving knife
and fixed knife.
Adjust VR7 (TSW).
Replace
the solenoid.
Replace TRM transistor circuit board.
Replace
the PSC box.
No
Replace the PSC box.
Replace BR transistor circuit board.
From the library of: Superior Sewing Machine & Supply LLC