Main Motor Does Not Turn Or Rotation Speed Is Slow - Brother XM3700 Service Manual

Failure Investigation for Electronic Parts
Main motor does not turn when
pressing foot controller.
Rotation speed is slow.
Is the sewing lamp turned on?
Does the pulley turn smoothly?
When unplug the foot controller plug from the
socket of the machine and turn on the power
switch, is the resistance between pins A of the
socket 60 to 80 Ω? (for 120V AC countries) *
Replace the foot controller.

Main motor does not turn or Rotation speed is slow

or
Y
Y
1
* Refer to Fig. 1.
*1 For 220 to 240V AC countries : 250 to 400 Ω
Y
5 - 3
N
Refer to "5-2 Sewing lamp
does not light".
N
Reassemble the upper shaft
assy.
N
Replace the motor 3P supply
assy.
A
Fig. 1