[midatlanticretro] WTD: Morrow Wunderbuss Thinker Toys

You are thinking of 2 different failure modes here. In an electorlytic capacitor, the dielectric (insulator) is a thin (oxide?) coating on the surface of the positive electrode. The electrolyte forms the engative electrode. If the electrolyte dries up, you get what's called a high ESR (effective series resistacnce). The capacitor appears as though it's got a high-ish value resisotr in sereis with it, and fails to, for example, smooth out ripple very well. The problem you're thinking of is when the dielectric film re-disolves into the electrolyte. The capacitor then appears as a short-circuit (2 electrodes connected by an electrolyte that's a good conductor). A high current can pass, the capacitor will overheat and blow itself apart. I've never found a variac very useful. In fact for some SMPSUs, which appear as constant power loads and draw more current as the input voltage drops, a variac can actually do quite a bit of damage to the primary side compoents. You'rs much better off removing the capacitors and re-forming them on a bench supply with a suitable series resistor to limit the current. -tony