Brother NV4000D Service Manual page 354

Failure Investigation for Electronic Parts The presser foot lifter does not work correctly
5 - 28
From previous page
Is the knee lifter sensor PCB
assembly correctly connected?
Y
When the knee lifter is operated
with the power on, does the voltage
between pins 2 and 3 on the main
PCB assembly (CN26) change
between 0 and 5 V DC?
Y
Is the ATPF INIT PCB assembly
correctly connected?
Y
When the presser is moved up and
down with the power on, does the
voltage between pins 2 and 3 on
the main PCB assembly (CN18)
change between 0 and 5 V DC?
To next page
N
Replace the main motor
N
Replace the knee
sensor PCB assembly.
N
Replace the main motor
N
Replace the ATPF INIT PCB
assembly.
lifter