Main Motor Rotation Abnormal - Brother NV4000D Service Manual

Failure Investigation for Electronic Parts Main motor rotation abnormal
Is there rotational variance in the main motor?
Does the rotation not reach top speed?
Can the speed not be adjusted?
5 - 10
or
or
When the speed controller lever is
moved with the power "on," does
the voltage between pins 3 and 1 on
the panel PCB assembly (CN6)
change between 0.3 and 2.9 V DC?
Y
When the upper shaft pulley is
slowly turned by hand, does the
voltage between pins 2 and 1 on
the main PCB assembly (CN15)
change between 0 and 5 V DC?
Y
Are the parts on the power PCB
assembly (Q603, Q608, Q611, and
Q612) free from discoloration or flaws?
N
Replace main PCB assy.
N
Replace VR PCB assy.
N
Replace NP PCB-D6 assy.
Y
Replace the power supply
unit (D6).