Abstract: A television apparatus has a horizontal deflection circuit with a transformer for developing a derived secondary power source. A circuit for disabling the horizontal deflection circuit is responsive to a fault condition in the horizontal deflection circuit. A driver stage in a vertical deflection circuit is energized by the secondary power source for supplying vertical deflection current to a vertical deflection yoke. An S-shaping capacitor is coupled in series with the vertical yoke. A circuit for sensing vertical yoke current includes a sampling resistor coupled in series with the vertical yoke and the S-shaping capacitor. The vertical yoke current sensing circuit generates a feedback signal for controlling the vertical deflection circuit during normal operation and generates a fault signal indicative of an overcurrent condition in the vertical yoke. Indication of the overcurrent condition is calibrated to be indicative of fault conditions in the vertical driver stage and/or in the S-shaping capacitor.