Technical information

149
Troubleshooting
(6) Bridge Circuit Breaker Open or Low AC Voltage
If the bridge circuit breaker or fuse is open or bus power has been interrupted, the drive will
display a “6”. A “6” fault can also be caused by a low AC line voltage. The drive must be
manually reset after restoring power. If logic power is maintained while bridge power is off,
position information remains in memory even if the motor shaft is moved. In most
applications a Home cycle will not be needed when bridge power is restored.
(7) Amplifier Bridge Temperature Fault
The drive has a thermal switch mounted on its power electronics heat sink. If the heat sink
temperature becomes excessive (greater than 80°C/176°F), the thermal switch will open. The
drive will shut down and display a “7” fault on the diagnostic display. The drive should be
allowed to cool before restarting. High ambient temperature can contribute to a “7” fault
condition.
(8.) Non-Operational Power Up Routine
During power up for the first second an “8.” appears on the display. The internal 16-bit
microprocessor is not operational during this time. Once the microcontroller is operating
correctly, the display will change to the appropriate character. In normal operation the drive
does not have a way to produce an “8.” error code.
( ) High AC Line Voltage
This fault occurs if the AC input voltage exceeds the maximum voltage specification of 264
VAC. Sustained voltage above 264 VAC will damage the drive. On the FX-490, 4120 and
6120, this fault cannot be reset until the bridge AC voltage is reduced to less than 150 VAC
or power is cycled “Off” then “On”.
(h) High DC Bus (FX-6200 to 8400 only)
This fault occurs when the internal DC bus voltage exceeds 425 VDC. This occurs if the shunt
regulator fuse is open or if shunt capacity is exceeded.
( ) Low AC Line (FX-6200 to 8400 only)
This fault occurs when the AC input to the FX drive drops below 196 VAC.