First, check the oven cavity is put too much food, power splitter switch is placed in the low fire position, the power supply voltage is low. Under the above conditions are met to ensure that the case, you can check the magnetron is aging, can be hand touch the tube, if you feel hot, the pipe is generally aging. In addition, the magnet on the crack pipe nor can it. The machine is used in the hotel kitchen, particularly humid environment, long-term frequent use, resulting in rusting magnetron connector, the contact resistance increased, leaving the low power supply voltage input, causing slow heating. After heating rust and replacement cables properly.NY4service manual download site