MAGUIRE MPA-6 Series Installation Operation & Maintenance page 22

M P A 
S e r i e s
2. Flashing of the number display indicates that the motor is unable to run at the proper
calculated speed. One reason for this may be that the counter setting is too high and the
cycle time too short for the motor to complete the metering even at full rated speed. The
other cause for the flashing display is that an obstruction is slowing the output shaft and the
automatic torque limiting feature is slowing the motor intentionally.
3. NO DISPLAY NUMBER at any time is usually a failed power supply. Be sure there is power
to the unit. Check the fuse. There is a fuse on the circuit board; however, this fuse usually
will not blow unless some other component on the board has failed. Replace only with a
fuse of the same amp rating.
4. DISPLAY of ONE ( 1) in the CONTINUOUS MODE indicates that the processor is
attempting to run the motor but is not picking up any RPM feedback from the armature.
Check (a),(b),(c) and (d) below if the motor does not run. Check (e) if it does run.
a. Components may be blown out on the circuit board. A reading of zero (0) VOLTS at
the motor FORWARD - REVERSE switch would indicate this.
b. The FORWARD - REVERSE switch may be turned off or may be faulty.
c. Brushes on the motor may not be making proper contact with the armature.
Sometimes brushes stick in their holders. A DC voltage at the motor leads without
corresponding motor rotation would indicate this might be the problem. Removal of
the brushes and light sanding of the brush sides will fix this.
d. The armature may be burned out. This will occur only with continuous overloading
and subsequent overheating. Circuit boards are designed to prevent this through a
torque-limiting feature. Armatures that burn up leave a distinct odor in the control box.
e. If the motor is running but the display is still one ( 1), check the magnet holding disk
on the motor armature shaft. It should be secure and there should be about 1/16 inch
space between the magnet holder and the electronic "hall effect" device on the back
of the motor housing. Also check this electronic device for proper location. It must be
positioned under the magnet cup and have no broken wire leads.
f. If the motor is running but the display is still one ( 1), check the magnet holding disk
on the motor armature shaft. It should be secure and there should be about 1/16"
space between the magnet holder and the electronic "hall effect" device on the back
of the motor housing. Also check this electronic device for proper location. It must be
positioned under the magnet cup and have no broken wire leads.
M A G U I R E P R O D U C T S , I N C .
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