YASKAWA F7 User Manual page 139

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Digital
Operator Display
Control Power Supply Undervoltage
UV2
Undervoltage of the control circuit when
CTL PS Undervolt
running.
Soft Charge Circuit Fault
UV3
The pre-charge contactor opened while the
MC Answerback
Drive was running.
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Table 6.2 Alarm Displays and Processing (continued)
Description
Diagnostics & Troubleshooting 6 - 14
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Cause
External load was pulling down
the Drive's power supplies, or
there was an internal short in the
power/gate Drive board.
Contacts on the soft charge
contactor were dirty and the soft
charge contactor does not
function mechanically.
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Corrective Action
Cycle power to the Drive.
Repair or replace the Power PCB/
Gate Drive PCB.
Remove all control wiring and
test Drive.
Cycle power to the Drive.
Check the condition of the soft
charge contactor.
Repair or replace the Power PCB/
Gate Drive PCB.