Brother T-8421B Instructions Manual page 58

11. TROUBLESHOOTING
Error code
y Is the machine connector inside the control
Err 5
box disconnected?
(Safety switch
operated)
y Is
y Was the power turned on while the treadle was still depressed?
Err 6
(Voltage drop)
y Is the power supply voltage too low?
This is displayed when there is a problem communicating with the operation panel
Err 7
CPU.
(Panel
y Is the operation panel connector inside the control box disconnected?
communication
error)
y Problem with operation panel or control box.
y This appears on the display when the sewing machine has been operating
Err 8
continuously for 3 minutes or more.
(Over time)
y This is displayed when the motor becomes abnormally hot and the temperature
Err 9
protection has activated.
(Motor
overheating
abnormally)
y Problem with motor.
y This is displayed when there is overcurrent in any of the solenoids (thread trimming,
Err 10
thread wiping, quick reverse or presser lifter).
(Solenoid
overcurrent)
y Problem with control P.C. board.
y Is connector CN5 inside the motor disconnected?
Err 11
(Problem with
motor over-
heating sensor)
51
Insert the connector securely.
the
machine head tilted back?
Return the machine head to its normal position.
Check the operation of the safety switch.
Return the treadle to the neutral position, and then turn on the power switch.
Check the power supply voltage.
Insert the connector securely.
Replace the operation panel or control box.
Turn the power switch off and then back on again, and then operate the
sewing machine normally.
After the temperature has dropped, turn the power switch back on and operate
the sewing machine as normal.
Replace the motor.
Check the resistances of the solenoids.
Replace the control box.
Insert the connector securely.
T-8421B, 8422B, 8452B, 8722B, 8752B
Possible cause Page
12*
*
3157M
*
*
**
3154M
**
**
**
*
3116M