A display system (10) which includes a CRT feedback current simulating circuit (20) to simulate the cathode feedback current directly from the from the red, green and blue output biases of the video processor (13). Furthermore, the display system (10) applies blanking to the references pulses applied to the CRT output driving stage (16) so that the reference pulses will not be visible during a vertical underscanned condition. Shifting the generation of the cathode feedback current prior to the application of the blanking prevents any significant distortion, modification or skewing of the cathode feedback current sensed by the AKB sensing circuitry (19) of the video processor (13).