Surge immunity of electronic equipment

Only 7 of the sample with 20 video recorders passed the impulse test without any failure. Almost all failures observed were located in the primary part of the power supply. Typically the radio interference suppression capacitors failed and/or internal fuses were blowing. Although the damage is rather small and limited to a few components, a rather expensive repair is required in any case. Since the radio interference suppression capacitors are the weakest point in the insulation system, either their quality has to be improved or some series impedance has to be used for suppression of the transients.