Warner Electric MCS-208 - Manual (Page 24)

24 Warner Electric • 800-825-9050 P-276 • 819-9045
Brake is not releasing as dancer is raised • Check the mechanical parts of the brake to assure they are in
(even though voltage decreases) good operating condition and properly installed. Check to see if
brake-on input is activated.
Symptom C: Dancer moves to and remains at upper limit after operating in a normal running position for a period of time.
Probable Cause Suggested Solution
Incorrect dancer position setting • Adjust dancer position setting until dancer moved to normal
running position.
Dancer pivot point sensor coupling has slipped • If dancer position adjustment lowers the arm near its normal
running position, realign pivot point sensor (see sensor mounting).
Faulty PC Board • With dancer position potentiometer and gain potentiometer at
minimum setting, (full CCW), check that the output to the
transducers approaches the minimum transducer input as the
dancer arm is raised. If input does not reduce, replace printed
circuit board assembly.
Drag torque of unwind stand and/or inertia of • With dancer position potentiometer and gain potentiometer at
rotating parts exceeds the minimum torque minimum setting (full CCW), check that the output to the
allowable for the application. (This problem recurs transducer goes to minimum as the dancer is slowly raised. If
near roll core only.) the output goes to minimum, check to make sure the transducer
is calibrated. Also, check to be sure the unwind stand friction or
inertia is not excessive for the application. Check the brake
selection procedure to be sure the brake being used does not
exceed the minimum allowable torques.
Symptom D: Dancer moves erratically - appears to hunt or oscillate.
Probable Cause Suggested Solution
Incorrect dancer gain setting. • Adjust dancer gain setting CCW until dancer stops hunting.
Non-uniform system friction. • If the hunting coincides with each revolution of the web parent
roll, check faulty bearings or mis-mounted brake.
Improperly installed sensor • When an MCS-605-1 sensor is being used, check to be sure the
index mark on the sensor shaft is aligned with the index mark on
the sensor body when the dancer is at the mid-travel position.
Also, be sure there is no lag between the movement of the dancer
pivot point and the shaft of the sensor - the sensor shaft must
move when the dancer pivot moves. With dancer centered, voltage
at terminal 6 and 7 should be 7.5 VDC ±0.1 VDC (refer to the
sensor mounting section.
Loose or faulty sensor and cable assembly • Check to be sure that all connections to the control terminal
block and the transducer wire connections are secure. Check
electric connector at sensor to be sure it is not loose. Using a DC
voltmeter connected between control terminals 6 and 7, check
to be sure the voltage variation is smooth as the dancer is slowly
moved through its travel limits. If the voltage variation is not
relatively smooth, either the sensor or cable assembly is faulty.
To isolate the fault to the cable or the sensor, turn off power and
disconnect the cable from the sensor and connect an ohmmeter
between the middle pin and one of the remaining pins on the
sensor receptacle. The resistance indication should vary smoothly
as the dancer is moved through its travel limits. If the indication is
erratic, the sensor should be replaced; if the indication is not
erratic, the cable assembly should be replaced. If above steps
seem normal, recheck dancer arm length (most application require
a dancer arm at least 12” long).