Cannot Sew Pattern Correctly - Brother PE770 Service Manual

Failure Investigation for Electronic Parts Cannot sew pattern correctly
The pattern is not sewn correctly.
When the upper shaft pulley is slowly
turned by hand, does the voltage
between pins 6 & 1, pins 4 & 1, pins
5 & 1 of CN7 on the motor PCB assy.
vary 0 – 5 V DC?
Is the FFC connected correctly
between the main PCB (CN5) and the
motor PCB (CN1)? Are both connector
locks applied correctly? Is the FFC
free breakage or short circuit?
Is the lead wire assy. (power) free
from breakage and connected
correctly between CN3 on the main
PCB and CN19 on the motor PCB?
Replace the main PCB assy.,
Replace the motor PCB assy..
Y
Y
Y
or
N
Replace the NP PCB assy.
Connect the FFC correctly or
replace it.
Reconnect the lead wire assy.
(power) correctly or replace it.
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