MULTISTRETCH 336-6/7/9 MOTOR CONTROL BOARD
CALIBRATION INSTRUCTIONS
Bias:
(RV3) The
RV3
pot controls the system bias.
This control injects an offset voltage that adds or subtracts from the voltage
reference defined by the external tension adjustment (film tension potentiometer);
this will allow extremes of adjustment to be set to levels consistent with proper
operation. Typically, the bias will be used to center the operation range in the
linear portion of its characteristics.
Note:
This adjustment is normally factory pre-set and should not
require field adjustment. For reference, the factory test procedure calls for a
setting of 1.3 volts DC at the cathode of Z1 (Zener Diode) achieved by adjusting
the
RV3
pot. Check for voltage between the (-IN) and the pin located next to the
bias trim-pot.
Span:
(RV1) The
RV1
pot controls the systems loop gain.
The system loop gain may be adjusted if the motor continues to be energized when
the dancer roller is unloaded and at rest. With the machine stopped, the pot should
be adjusted to ensure that the motor is de-energized in this condition, and so that a
light pull on the free end of the film causes the film to feed freely. Counter
clockwise (CCW) adjustment of this pot will increase the response time, in effect
softening the motor tension response plus decreasing the maximum motor speed
attainable. Clockwise (CW) adjustment will decrease the response time, in effect
sharpening the motor response time plus increasing the maximum motor speed
attainable.
Current Limit:
(RV4) The
RV4
pot controls the torque (amperage) that the 336
board will allow to the motor.
To protect the unit against damage should the motor stall, jam, or current demands
exceed its rating, a current limiting circuit is included which keeps motor current at
a safe level regardless of motor load or input from the Hall effect proximity switch.
