Microwave heating is slow, there are usually three reasons : First, the microwave power transmission magnetron aging leads to decline : the second is missing content or high voltage capacitor leakage : Three high-voltage rectifier diode forward resistance increases ( generally about 100kΩ) or reverse resistance reduced ( normal infinity ) . The above will result in reducing the negative high voltage applied to the magnetron filament (due to the magnetron anode grounded , so the ground is negative high voltage filament , filament emits electrons capabilities that reduce the emission of microwave power magnetron For magnetron determine whether aging , the traditional method is to measure the filament resistance , under normal circumstances, should be less than 1Ω, and the smaller the better , but in the actual measurement would be difficult and this is because those who do not have general maintenance milliohm meter or bridge, for milliohms resistance level changes indistinguishable Moreover, even if the magnetron serious aging , the filament resistance rarely exceeds 1Ω. according to the author 's practice , in the microwave powered on, use a multimeter 2500V dc magnetron filament voltage measurement block pin ( pin no matter what the root can ) to ground voltage ( the vast majority are directly heated cathode magnetron ) , the normal -2000V is generally about ( refer to 220V mains input for the next case , slightly different models discrepancy ) If voltage is significantly low, then the content or high-voltage high-voltage rectifier diodes have a problem if the measured filament normal voltage to ground , the base can be determined magnetron aging. M is a method to select the microwave the maximum firepower block, then clamp meter measuring mains input current at this time , under normal circumstances, is approximately equal to the rated power divided by microwave mains voltage if significantly smaller , then reduce the magnetron cathode electron emission capability , has serious aging. example, a Marlboro WD-1200 microwave oven ( rated power 1200W), heating efficiency is significantly reduced. opening the enclosure , measuring the magnetron filament voltage to ground to -2000V, pursuant to explain high-voltage capacitors and high voltage rectifier diode normally. and then measuring the mains input current is only about 3A ( with DC magnetron filament resistance bridge measurement 750mΩ).

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