Brother PE770 Service Manual page 213

Repair Manual
Problem Primary factors and causes
1 Stitch skipping Needle tip damaged while
Thread abrasion sewing
Thread breakage Needle catches and bends
Seam unevenness before or after sewing
Needle breaks
2 Power supply FFC (FFCSFBNCD-50) and main
enter, but LCD PCB assy. connector disconnected
display nothing
FFC (FFCSFBNCD-50) and motor
PCB assy. connector disconnected
Lead wire assy. power and main
PCB assy. connector
disconnected
Lead wire assy. power and motor
PCB assy. connector
disconnected
LCD and main PCB assy. FPC
disconnected
Power supply unit and motor
PCB assy. connector
disconnected
Inlet assy. and power supply unit
connector disconnected
Bad main PCB assy.
Bad motor PCB assy.
Bad LCD
Bad power supply PCB assy.
Bad inlet assy.
Bad power supply cord
Sewing machine PCB unit: LED lamp-FL and
lamp (LED lamp) motor PCB assy. connector
does not light disconnected
(machine operation
PCB unit: LED lamp-FR and
normal)
SSVR PCB assy. connector
disconnected
Bad PCB unit: LED lamp-FL
Bad PCB unit: LED lamp-FR
Bad SSVR PCB assy.
Bad motor PCB assy.
Bad main PCB assy.
START/STOP SSVR PCB assy. and main PCB
lamp does not light assy. connector disconnected
Bad SSVR PCB assy.
Bad main PCB assy.
6 - 2
Repair method
Needle replacement
Lock FFC after plug FFC in
connector (3-34)
Lock FFC after plug FFC in
connector (3-35)
Plug connector in (3-34)
Plug connector in (3-35)
FPC plug connector in (3-34)
Plug connector in (3-27)
Plug connector in (3-27)
Replace main PCB assy.
(2-7) (3-34)
Replace motor PCB assy.
(2-15) (3-25)
Replace LCD (2-8) (3-33)
Replace power supply unit
(2-13) (3-27)
Replace inlet assy. (2-14) (3-26)
Replace power supply cord
(2-13) (3-27)
Plug connector in (3-35)
Plug connector in (3-31)
Replace PCB unit: LED lamp-
FL (2-13) (3-28)
Replace PCB unit: LED lamp-
FR (2-10) (3-31)
Replace SSVR PCB assy.
(2-10) (3-31)
Replace motor PCB assy.
(2-15) (3-25)
Replace main PCB assy.
(2-7) (3-34)
Plug connector in (3-31) (3-34)
Replace SSVR PCB assy.
(2-10) (3-31)
Replace main PCB assy.
(2-7) (3-34)
Items for Inspection method
Inspection and standards
Tip damage to Touch the needle tip
needle with your finger, be
sure that it is not
damaged.
Needle curvature Remove the needle,
place on level block
(horizontal block) and
be sure there is no
curvature.
Sewing machine When power is
runs when switched ON, conform
switched on that the LCD screen
light.
(4-2)
(4-2)