First the setup - Olympus C4000-Z external flash connection to PC to household adapter cord Household to Wein SSH Inline Household voltage regulator Voltage regulator to household cord Household cord to Household to PC adapter cord PC connection to Nikon SB-24 flash laying on desk One snap of the camera and the external flash did not fire and there was smoke coming from the shutter button. I quickly unplugged everything at that point. My question is this - does the flash need to be in the metal hot-shoe for grounding purposes or something and is this where I probably went wrong? I did test this rig the other night with all the same connections with the exception that the flash was mounted in a metal hot-shoe holder on top of a light stand. The flash wouldn't fire with the voltage regulator in place. If I removed it from the chain, the flash fires with no problems and no smoke.