Abstract: A convergence control system for a television apparatus, for example a projection television, comprises: a plurality of channels, each channel having a digital memory for storing a set of grid coordinate values defining a convergence correction grid; and, a pair of multiplying digital to analog converters for the grid coordinate values. A single circuit for generating sequential digital addresses is coupled to each of the channels for outputting the grid coordinate values from each of the digital memories to respective multiplying digital to analog converters of the channel. The values of respective horizontal grid lines are supplied to only one of the multiplying digital to analog coverters. A single waveform generator develops a pair of analog waveforms of complementary phase for modulating respective multiplying digital to analog converters of each pair in each channel. The sum of the modulating waveforms is constant.