Abstract: A maintenance supervisor was summoned to repair a Thermonic soldering machine (Model No. 50, Serial No. 184148). Suspecting that the problem was of an electrical nature, the employee removed the top cover of the electrical unit of the soldering machine. The unit converted 120-volt single-phase alternating current into 6200-volt direct current. The current was then applied to an oscillator circuit, which produced high-frequency power for the soldering process. The unit was provided with an interlock to deenergize the equipment when the cover was removed. To bypass the interlock, the maintenance supervisor took a screwdriver and jammed it into the switch. Suspecting that the short was located in an oscillator, he then took a small pair of pliers in his right hand (keeping his left hand free) and began adjusting the oscillator tube. He got the unit to cycle one time, but then it malfunctioned again. The employee again took the pliers in his right hand to adjust the tube. The handle of the pliers was covered with rubber; however, there was a tiny hole in the rubber at the base of the handle. This time his hand was over the hole in the rubber. The maintenance supervisor rested his arm on the metal enclosure of the unit while he adjusted the tube. He received an electric shock, which knocked him backward away from the unit. He stood there dazed as the operator notified the assistant production manager of the accident. The maintenance supervisor was hospitalized for his injury. The maintenance supervisor had been trained in the operating process of the machine itself, but had not been trained to service the electrical portion of the machine. The operator's manual and schematics were not available at the worksite. They were maintained at another plant.