A first transformer is coupled to a deflection yoke and coupled to a derived secondary voltage source for driving a load, for example, for generating an ultor voltage. An on/off switch is responsive to an on/off signal. A second transformer has a primary winding coupled to the switch and coupled to a voltage source and has a secondary winding coupled to the first transformer. A first sampling circuit generates a first feedback signal indicative of current flowing from the secondary winding to the first transformer. A first safety circuit responsive to the first feedback signal controls the effect of the on/off signal on the switch when the current flowing from the secondary winding to the first transformer exceeds a threshold, by limiting the on time of the switch to limit the peak value of the current. A second sampling circuit generates a second feedback signal indicative of the ultor voltage. A second safety circuit responsive to the second feedback signal controls the effect of the on/off signal on the switch when the ultor voltage exceeds a threshold, for example due to picture tube internal arcing, by interrupting propagation of the on/off signal to block operation of the switch. A third sampling circuit senses current conducted by the switch and generates a third feedback signal. One of the first and second safety circuits is also responsive to the third feedback signal. The switch, the transformer and the deflection yoke can be coupled in a Wessel configuration.