Electronics AC - Manual (Page 7)

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Caution:
Any customer attempts to modify or repair the product during the warranty period will
terminate the warranty. Standard technician labor rates will be quoted prior to repair.
10. UPGRADES - REVISIONS
Design improvements are constantly being made to our products. Please contact Electronics In-
corporated for details. When ordering spare units, please refer to model number and serial num-
ber of each unit.
11. AUTO-ZERO FEATURE
An auto-zero feature is available to maintain a true zero reading during the motor-off condition.
This circuit monitors the motor current signal and forces it to zero whenever the motor is off and
the Enable signal is absent. A blue LED on the front panel indicates the auto-zero is active.
When the valve Enable signal is present the auto-zero function is disabled.
12. TROUBLESHOOTING GUIDE
1. Unstable operation
a. Several conditions can affect motor current stability. It is important to determine if the
problem is caused by the machine or by the MagnaValve.
i. Place the servo switch (2 - 11) to the off (down) position.
ii. Turn the machine on and apply the Enable signal to Terminal #3 or place mode
switch to on (right) position.
iii. Slowly turn the setpoint control (1-9) clockwise to increase the motor amps until ei-
ther the panel display reading is at desired value or the motor amps display is at
the desired value. The motor amps feedback signal does not affect the controller
stability in this mode (servo off). Therefore, the wheel is the only cause for instabil-
ity.
b. To demonstrate this further, another test can be performed.
i. 1. Close the slide gate above the MagnaValve.
ii. 2. Start the wheel and apply the Enable signal.
iii. 3. Turn the setpoint control (1-9) to 100% or full clockwise position. The red LED
valve light will be constantly on and the MagnaValve will be in its maximum flow
condition. Slowly open the slide gate and observe the wheel ammeter for stability.
iv. 4. If the motor current is unstable, the problem is due to the machine, not the Am-
perage Controller or MagnaValve.
c. If the machine uses a variable speed drive, check it for stability or bypass it with a con-
ventional motor starter. The instability may be caused by flooding/choking the wheel or
demanding more shot than the wheel can supply.
i. Check for obstructions or restrictions or unnecessary bends in the flow path.
ii. Worn blades or damaged control cages will not pass as much shot as new blades,
therefore, as blades wear, the maximum motor amperage is reduced.
iii. Shot condition is very important. Unclean shot due to oil, water or dust, can cause
erratic flow performance. Dust can be generated by shot deterioration, or by abra-
sion of parts being peened, the cabinet, or the tooling. Dust will tend to cake and
clog the flow. Under severe conditions, the MagnaValve may become completely