Brother PR655 Service Manual page 283

Failure Investigation for Electronic Parts
• Main motor encoder signal error
• Main motor encoder connect error
(Dialog message)
Is the main shaft encoder deformed,
bent, or damaged due to contact?
Is the main shaft sensor's lead
properly connected to CN19 on the
main PCB?
Does the machine function normally
when the main shaft sensor PCB is
replaced with a reliable one?
Change the main shaft
sensor PCB.
Error message
Y
Y
Y
5 - 28
N
Change the main shaft encoder.
N
Connect it properly.
N
Change the main PCB.