Panasonic NN-H264SFR Service Manual

Also see for Inverter NN-H275: Operating instructions Operating instructions Service manual

DANGER OF HIGH VOLTAGE AND HIGH /TEMPERATURE (HOT/LIVE) OF THE INVERTER /POWER SUPPLY (U)This High Voltage Inverter Power Supply circuitsupplies very high voltage and very high currentfor the magnetron tube. Though it is free fromdanger in ordinary use, extreme care should betaken during repair. As you can see, it looks like aTV flyback transformer, however the current isextremely large and so danger exists because ofits high current and high voltages.The aluminum heat sink is also energized withhigh voltage (HOT), so do not touch when ACinput terminal is connected to the power linebecause one of the IGBT switching power devices(Collector) is directly connected to the Aluminumheat sink.The Aluminum heat sink may be HOT from heatenergy; therefore, extreme care should be takenduring servicing and replacing.WARNING OF INVERTER POWER SUPPLY (U) /GROUNDINGCheck the High Voltage Inverter Power Supplycircuit grounding. This High Voltage InverterPower Supply circuit board must have a properchassis ground by the grounding bracket to thechassis ground; otherwise, this H.V. Invertercircuit board will expose very high voltage andcause extreme DANGER! Be sure to have propergrounding by the grounding plate and screws.WARNING OF DISCHARGING HIGH VOLTAGECAPACITORSWarning about the electric charge in the highvoltage capacitors. For about 30 seconds after theoven is turned off, an electric charge remains inthe high voltage capacitors in the inverter powersupply circuit board.When replacing or checking parts, remove thepower plug from the outlet and short the Inverteroutput terminal of the magnetron filamentterminals to the chassis ground with an insulatedhandle screwdriver to discharge. Please make sureto touch chassis ground side first then short to theoutput terminals.17