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HARRIS
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WARNING: Disconnect and lockout AC primary power prior to servicing
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9.3.0.2 Over-voltage
Fault troubleshooting is started by replacing the power supply control card. Check the
wire number 19 from the board socket J2 to the L2 choke output. A common problem is
a D connector pin that did not latch during assembly and the pin works back out of the
connector shell.
9.3.0.3 Over-current
Remove drive from that cabinet and check meter reading of current. Pull all modules
above that supply to remove the load. Try another control card. Check the connection
integrity of the wiring around the current shunt.
9.3.0.4 Breaker Trips
•
Wall breaker trips when cabinet turns on:
Check for shorts from line to ground. If the harmonic choke appears overheated,
the choke could have a winding to frame short.
•
Control breaker trips at turn on:
The protection unit on the contactor K1 could have shorted. Otherwise investigate
for a wire to ground short.
9.3.0.5 Slave Controller Power Supply Fault Indication
This is not a fault that has a LED indicator on the supply control card. The slave
controller fault is reporting that the GO/NOGO signal is not present. A common
problem related to this fault is one SCR is not firing. Often this results in a power
supply that you can hear making a low frequency noise.
Connecting a scope to the input of the filter choke will show the missing pulse from the
SCR that is not firing. The easiest way is to connect the scope probe to the left terminal
of the diode CR1, which is mounted on the front of the fan cooled heat sink. This the
cathode terminal and is electrically connected to the choke input.
A SCR that is not firing usually is a wiring problem, check the wiring to J2 that the card
plugs into and the small connector at the gate of the SCR. Substitution of a suspect SCR
with a good SCR is the best way to find a bad SCR.