Brother NS-10 - Pulse motors do not return to starting point

5 - 4
Failure Investigation for Electronic Parts Pulse motors do not return to starting point
When the power is turned ON, the pulse motors do not return to the
starting point.
• Needle up: Z pulse motor return to starting point
• Needle down: F pulse motor returns to starting point
Replace the pulse motor
Replace the main PCB assy.
Attach the main PCB assy. to
the correct position of the
shutter cover
Is the resistance between the 1 & 2 pins
and 3 & 4 pins on the pulse motor
connectors 6.7 – 7.7 Ω?
Regardless of needle position this
pulse motor returns to the starting point
Is the voltage between pins 3 & 4 of CN5
on the main PCB assy. 30 V DC?
N
N
Replace the power supply
PCB assy.
N
Y
Y
Y
Reconnect it correctly
Is the connector of the Z pulse motor
correctly connected to CN8 of the main
PCB assy.?
Is the connector of the F pulse motor
correctly connected to CN10 of the main
PCB assy.?
N
Reconnect it correctly
N
Y
Y