Color television CRT beam current correction circuit

A colour television display apparatus including a beam current reference level control circuit comprising a measuring circuit included in the cathode circuits of the electron guns of a multi-gun colour display tube for measuring during a measuring period the beam current reference level to be corrected, a level insertion circuit for providing during this measuring period a reference level in a video signal to be applied to each gun of the display tube, and a beam current level correction circuit coupled to the measuring circuit and to a control electrode of each gun of the display tube for obtaining substantially the same beam current reference level in each of the electron guns, wherein said control circuit further comprises a level shift circuit coupled to the electron guns of the display tube for shifting, at each electron gun over substantially the same amount, the mutual position of the reference level in the video signal and a setting voltage of the electron gun occurring outside the measuring period, relative to that mutual position during the measuring period.