Haas Alarm: 648 (M) DC BUS SHORTED – A shorted 320VDC bus condition was detected upon power-up. The DC bus monitor detected an improper charge-up. This can be caused by a shorted capacitor in 320V PS, shorted cable, shorted servo amplifier or shorted spindle drive. This can also be caused by a low incoming power. Check the Amplifier. Check the incoming AC lines. Cycle Power to Continue! This is only tested at power-up. If this fault occurs, it cannot be reset.