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Electronic Parts
Failure Investigation for Electronic Parts
Main motor does not turn
Y
Lower the presser foot lifter.
Is the presser foot lifter shaft down?
Is the PF switch assy. resistance
normal?
• PF switch assy. resistance
Switch pressed … 1 Ω or less
Switch released … ∞
N
Attach the main PCB assy. to
the correct position of the
shutter cover
Is the main PCB assy. attached to the
correct position of the shutter cover?
N
N
Y
Y
Replace the PF switch assy.
From previous page
Replace the operation PCB assy.
or
Replace the main PCB assy.
or
Replace the power supply PCB
assy.
Are the resistance values for the
Stop/Start switch, reverse switch,
raise needle switch and the thread
cut switch normal?
• Switch resistance values
Switch pressed … 1 Ω or less
Switch released … ∞
N
Reconnect it correctly
N
Is the FFC of the operation PCB
assy. correctly connected to CN4 of
the main PCB assy.?
Y
Replace the SS-VR PCB assy.
Y
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