5 - 8
Failure Investigation
for Electronic Parts
Pulse motor does not return to initial position
When the power is turned ON, the pulse motor does not return to the initial position.
• When needle is up : Z pulse motor returns to it's initial position.
• When needle is down : F pulse motor returns to it's initial position.
N
Y
Is the resistance between pin 1 and
2, 3 and 4 on the pulse motor
connector 6.7-7.7Ω?
N
Replace the ZPM lead wire assy.
Replace the pulse motor.
N
Y
When the Z pulse motor does not
return to it`s initial position, is the
resistance between pin 1 and 4, 2 and
3, 3 and 2, 4 and 1 at the ZPM lead
wire assy. 1Ω or less?
Y
Replace the FPM lead wire assy.
When the F pulse motor does not
return to it`s initial position, is the
resistance between pin 1 and 4, 2 and
3, 3 and 2, 4 and 1 at the FPM lead
wire assy. 1Ω or less?
Replace the main PCB assy.
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