The Presser Foot Lifter Does Not Work Correctly - Brother NV4000D Service Manual

Failure Investigation for Electronic Parts The presser foot lifter does not work correctly
Is the resistance of the SS PCB
assembly and thread PCB assembly
switch normal?
Resistance of each switch
When switch is pressed : 0 Ω
When switch is released : ∞
Are the main PCB assembly (CN3)
and PF initial sensor PCB assembly
correctly connected?
When the slit section of the PF initial
sensor PCB assembly is switched to the
open / closed position with the power
on, does the voltage between pins 2
and 3 on the main PCB assembly (CN3)
change between 0 - 3.3 V DC?
Is the presser correctly adjusted?
Is the knee lifter correctly adjusted?
Abnormal presser foot lifter
behavior
Y
Y
Y
Y
Y
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Adjust the SS PCB assembly
and thread PCB assembly,
or
N
replace the SS PCB assembly,
or
replace the thread PCB.
N
Replace the main motor
N
Replace the PF initial sensor
PCB assembly.
N
Replace the main motor
N
Readjust the knee lifter correctly.
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