Cannot Sew Pattern Well - Brother NV4000D Service Manual

Failure Investigation for Electronic Parts Cannot sew pattern well
With the power OFF, can you lightly
move the needle bar left and right by
hand?
Is the resistance between the pins
at the ends of each pulse motor
lead wire 1 Ω or less?
Z and S pulse motor lead wires
Between pins 1 & 1, 2 & 2, 3 & 4, and 4 & 3
F pulse motor lead wire
Between pins 1 & 1, 2 & 2, 3 & 3, and 4 & 4
Is the resistance between pins 1 & 2
and 3 & 4 on the Z, F, and S pulse
motor connectors normal?
When the upper shaft pulley is slowly
turned by hand, does the voltage
between pins 2 & 1, 4 & 1, 5 & 1, and 6
& 1 on the main PCB assembly (CN15)
change between 0 and 3 V DC?
Normal pattern is not generated
Y
Y
F pulse motor: 4.5 - 6.5 Ω
Z and S pulse motors: 5 - 7 Ω
Y
Y
Replace main PCB assy.
N
Adjust the attachment of the
needle-presser module
N
Replace the pulse motor lead
wire.
N
Replace pulse motor
N
Replace NP D6 PCB assy.
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