-7-
4.
CONTROL SYSTEM BLOCK DIAGRAM (BL6800 only)
5.
MOTOR UNIT CONTROL (BL6800 only)
The main motor for the sewing machine is required to smoothly change from low speed to high speed without any
fluctuation due to load or power supply fluctuations or temperature change. It must also take into account greater
ease-of-use for the sewing machine, for example starting up slowly when starting up and stopping with the
needle up. To fully comply with these requirements, BL6800 uses a microcomputer for PWM control and
controls the main motor with power MOS FETs.
6.
OTHER ELECTRONIC COMPONENT FUNCTIONS (BL6800 only)
Start/stop(SS) switch ........................... used to start and stop (SS) the machine. If you want to start sewing at low
speed, keep this switch depressed and start sewing.
Backstitch(BK) switch .......................... used for backstitching and reinforcement stitches. While this switch is
held down, the sewing machine backstitches at low speed in the reverse
direction. (However, when the foot controller is used, the speed does not
become slow speed.)
Speed (adjustment) volume ................ a slide control used to set the sewing machine rotation rate
Needle position(NP) sensor................. detects the drive timing of zigzag and feed pulse motors and detects the
(Rotation Sensor)
vertical position of the needle. Also detects the turning angle of the upper
shaft by means of a photointerruptor and shutter installed on the upper
shaft.
Speed sensor (Rotation Sensor) .........
used to detect the rotation speed of the main motor.
detects the operating speed of the main motor by means of a
photointerruptor and shutter installed on the upper shaft.
Foot controller jack .............................. when using the foot controller, connect it to this terminal.
Transformer......................................... used for driving the pulse motors, to illuminate the lamps and to supply
power to the electronic circuitry.
WB light (Lamp)................................... is 12V 5W.
Bobbin winder(BW) switch .................. used to detect whether the bobbin winder has been set when winding the
lower thread.
CPU 32 pin
Drive circuit
Reset circuit
Speed sensor
Needle position (NP)
Foot controller
Speed volume
Start/stop switch
Backstitch
(BK) switch
Bobbin winder switch
Buzzer
Main motor
