Troubleshooting, Manufactured by – Precision Control Systems 1029C User Manual
Page 20
MODEL 1029C
16
10/19/2007
TROUBLESHOOTING
CAUTION: HIGH VOLTAGES ARE PRESENT ON THIS
CONTROLLER AND ON PORTIONS OF THE PRINTED
CIRCUIT BOARD. USE EXTREME CARE TO AVOID
ELECTRICAL SHOCK.
Notes: The LED's provide a convenient method of
determining the general location of controller problems.
The
LOAD LED indicates that 10% or more of rated load
current is present. The intensity of the
LOAD LED should
increase as the command signal is increased. The
COMMAND LED indicates the presence of gate drive. The
O.C.T. LED is a fault indicator to warn that an Over Current
condition has occurred, the O.C.T. relay is energized and
the SCR's are prevented from turning on. The
SHORTED
SCR LED is a fault indicator to warn that one or more
SCR's may be shorted.
NO LOAD VOLTAGE:
• Determine that the Command LED lights when the
command signal is increased from zero.
If the command LED will not light.
• Determine that the following conditions exist: (Measure
voltages at screw terminals to ensure good electrical
connections.)
• Determine if
OVER CURRENT TRIP LED is ON.
• Voltage between COM (Pin 14) and +5CW (Pin 12) must
be 5 Volts ±1. If not; Circuit is not powered or command
connections are shorting out supply.
• Determine that line voltage exists between Line 1 and
Line 2 terminals.
• Determine that fuses on controller are OK.
• Remove connections to CW (terminal 12).
Voltage or potentiometer inputs.
• Determine that voltage from COM (pin 14) to IDLE (W)
or RUN (W) changes from 0 to 5 Vdc as command is
changed from zero to 100%.
4/20 mA inputs:
• Determine that voltage from COM (pin 14) to IDLE (W)
or RUN (W) changes from 1.2 to 6 Vdc as command is
changed from 4 to 20 mA.
• Determine that there is no connection between terminals
9 & 10.
If the command LED can be made to light:
• Determine that the load fuses are OK and that the load
has continuity. Load continuity (including load fuses can
be confirmed by determining that the supply voltage
exists between Line 1 and Load 1 terminals when the
command signal is zero.
LOAD VOLTAGE WILL NOT GO TO ZERO:
If RMS value of the load voltage is greater than 10
percent of the supply voltage.
• Determine
SHORTED SCR LED status while varying the
command signal.
• With power removed and the load disconnected from
terminal Load 1 the resistance between terminals Line 1
and Load 1 should be greater than 100K ohms.
• If the resistance between Line 1 and Load 1 is less than
100K ohms the SCR module has failed.
• If the shorted SCR led is ON & the resistance between
Load 1 and Line 1 is greater than 1000 ohms, the failure
is likely associated with the circuit board. Determine by
removing the circuit board and applying power.
• Determine that the supply to line 2 and the load are
connected to the same supply.
If the RMS value of the load voltage is less than 10
percent of the supply voltage.
• Determine that the command signal is correct. Adjust
the zero and span potentiometers to achieve the desired
output. (Note: The Zero and span potentiometers are
factory set. Adjustment should be made with caution.
FULL VOLTAGE CANNOT BE OBTAINED:
• Determine that the control signal is at maximum.
• Determine that the controller is not in current limit
Decrease the current limit by rotating the current limit
potentiometer counterclocklwise, the controller is in
current limit if the load voltage decreases.
• If the problem occurs on initial start up, determine that
line 2 and the load are connected to the same supply.
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