Bobbin Winding Cannot Be Done - Brother NV4000D Service Manual

Failure Investigation for Electronic Parts Bobbin winding cannot be done
5 - 20
The bobbin winder motor
does not rotate.
Is the bobbin winder mechanism
assembled and attached correctly?
Y
Is the resistance between pins 1
and 2 on the BW switch assembly
(D6) connector normal?
When bobbin presser is in bobbin
winding position : 1 Ω or less
When bobbin presser is not in
bobbin winding position : 8
Y
Is the resistance of the bobbin winder
motor between 72 and 92 Ω ?
Y
Replace main PCB assy.
Adjust the bobbin winder
N
mechanism for correct
assembly and attachment
N
Replace the BW switch
assembly (D6).
N
Replace the BW motor
assembly.