Large-scale integration parts are easily damaged by the transient currents that result from e.h.t. flashover in a cathode-ray tube. It is therefore necessary during design to provide adequate circuit protection and, further, to ensure by testing that the protection is sufficient to remove the likelihood that flashover-induced failures will happen during normal operation.The purpose of this work was to evolve a test method that could achieve universal acceptance, so that it could be applied to both monochrome and colour units containing hard- or soft-flash c.r.t.s.The method chosen usesQ-switched laser pulses to initiate flashover discharges to the focus electrode and then employs the focus-to-final-anode gap as a surrogate spark gap to transfer flashover energy to the remaining c.r.t. connections. The measurements taken during manufacturing plant life-testing have been used to confirm the number of discharges required in a test to verify design.