Abstract: A color television receiver having a circuitry for automatically adjusting the cut-off points of the electron guns, i.e. for adjusting the bias of each electron gun to make the guns responsive to video signals in a constant manner, wherein the bias and the video signal are both applied to the cathode of each gun through a switch. In permanent connection with the cathode is mounted an integrator operable to adopt and substantially maintain the bias voltage upon said switch being switched off, and in series with the integrator is arranged a current amplifier for detecting the cathode current in said series connection upon the other end thereof being connected to ground simultaneously with the switching off of said switch.