Bobbin Thread Detection Does Not Work Normally - Baby Lock BLSY Service Manual

Failure Investigation for Electronic Parts Bobbin thread detection does not work normally
Bobbin thread detection does not
work normally
Are the main PCB assembly and
photo
correctly connected?
Are the main PCB assembly and
photo transistor PCB assembly
correctly connected?
When another photodiode PCB
assy. is connected to CN19 of the
main PCB assembly. and brought
into
phototransistor PCB assy., does it
operate normally?
When
PCB assy. is connected to CN18
of the main PCB assembly. and
brought into the proximity of the
photodiode PCB assy., does it
operate normally?
diode PCB assembly
Y
Y
the proximity of the
N
another phototransistor
N
Replace main PCB assy.
Reconnect the main PCB
N
assembly and photo diode
PCB assembly.
Reconnect the main PCB
N
assembly and photo transistor
PCB assembly.
Y
Replace the photodiode PCB
assy.
Y
Replace the phototransistor
PCB assy.
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