Microwave oven vulnerable device detection \x0d\ 1. high-voltage diode \x0d\ Normal, measured with a multimeter Rx10k block, forward conduction (with a certain resistance), reverse cutoff (resistance infinity); with other resistance block to measure the resistance of the forward and reverse direction are not. High-voltage diode damage is mostly breakdown, that is, both positive and negative pass. High-voltage diode damage caused by fault phenomena are: burning high-voltage insurance, or microwave oven operation does not heat up, microwave operation does not heat up and increased noise. \x0d\ 2. magnetron \x0d\ normal, measured between the two terminals for the zero point a few ohms, the two terminals on the shell is not passable between (resistance value of infinity). Magnetron damage, some of the performance of the filament between the two terminals open circuit, some of the performance of the two terminals on the shell conductive to form a pathway, some can not be measured directly. Magnetron damage induced by the phenomenon of: microwave oven running sound is small, does not heat, or burn the power supply insurance, high-voltage insurance, high-voltage diodes. \x0d\ 3. high-voltage transformer \x0d\ normal, measuring the resistance between the two inputs is less than 31 - /, filament winding resistance is also very small nearly OQ, high-voltage winding resistance is larger in the 9011-150f1. high-voltage transformer damage to the high-voltage winding turn-to-turn short-circuit mostly. Damage caused by the phenomenon are: running current increase in odor, or running without heating, smoke. \x0d\ 4. high-voltage capacitor \x0d\ its capacity in 1 ib F or so, there is a 9MQ resistor in parallel. Normal, the pointer multimeter placed in the Rx 10k block, the two pens were connected to the two poles of the high-voltage capacitor, the measurement of the beginning of a certain resistance value but not high, and then gradually rise to about 9MQ; two pole pieces of the shell resistance should be infinity. The actual maintenance of high-voltage capacitor failure is relatively low, the common form of damage is the pole piece or insulation wood fire, individual failure or breakdown. High-voltage capacitor damage caused by the phenomenon of burning power supply fuse or high-voltage fuse, microwave oven can run but not heating, etc. e\x0d\ 5. Mechanical timer / fire selector \x0d\ Normal, the measurement of the motor at both ends of the resistance, clockwise twist the time knob, the timer switch contact conduction. The fire contact is on and off when the motor is rotating. Timing switch contacts are damaged, causing the whole machine does not work; fire switch contacts are damaged causing the microwave oven to run without heating; motor damage causing the microwave oven to run and heat non-stop, or run without heating, without stopping. \x0d\ 6. Door switch \x0d\ Door switch contains several light touch switches. Under normal conditions, there is a tiny contact switching sound when the switch is closed. Damage to the fault performance: the whole machine does not work, running not heating, burning power supply fuse when the door is opened. \x0d\ 7. bidirectional diode \x0d\ will pointer multimeter placed in the Rxlok block, the two pens were connected to the bidirectional diode poles, forward and reverse resistance should be infinity. Bidirectional diode breakdown, leakage, generally cause the microwave oven does not heat or the power supply fuse burned out. Check if there is no such tube, can be removed without removing the removal of the circuit has no effect on the work, but the opportunity to lose high-voltage over-voltage protection. \x0d\ 8. Thermal relay \x0d\ also known as thermal cut-off, temperature limit switch, thermal switch, etc., belongs to the automatic reset thermal protection components. The multimeter will be placed in the RxlO block, the two pens were connected to the two terminals of the thermal cutoff, the resistance value at room temperature should be Oil, high temperature and to reach its marked value of the resistance value should be infinity, when the temperature drops to a certain value and automatically become 011. thermal relay is damaged, it should be replaced with the same specifications of the parameters of the relay, such as replacement of the labeled temperature is too low will cause misprotection; replacement of the labeled temperature is too high to achieve the purpose of protection. \x0d\\\x0d\ 2, common troubleshooting \x0d\ 1. power on no response, fuse fuse Check the door switch, microwave high-voltage system (high-voltage transformer, high-voltage diode, magnetron, high-voltage capacitors), fan motor, turntable motor. After troubleshooting, you can replace the fuse and try the machine. \x0d\ Tip: Check the high-voltage transformer is mainly to observe the primary winding, high-voltage winding there are no traces of burning, there is no insulating paint burnt flavor. \x0d\ 2. power on no response, the fuse is not damaged \x0d\ Mechanical control store type microwave oven two can check the mechanical timer, magnetron temperature limiter. Computer-controlled microwave oven: observe the computer board fuse, check the computer board power transformer, magnetron temperature limiting protector. After troubleshooting, you can replace the insurance test machine o\x0d\ 3. Repeatedly burned power supply fuse First check the door switch, high-voltage transformer, and then check other devices in the microwave system, such as high-voltage diodes, high-voltage capacitors, bi-directional diodes, magnetron and so on. \x0d\ 4. can run, but the microwave does not heat First measure the high voltage transformer primary power supply, and then determine the scope of maintenance according to the results of the measurement. If the measurement of the high-voltage transformer primary no AC220V power supply, mechanical control of microwave ovens, should check the timer, door switch; computer-controlled microwave ovens, should check the door switch, computer board fire relay and drive transistor. If the measurement of high-voltage converter primary AC220V power supply, then check the high-voltage transformer, high-voltage insurance, high-voltage diode, protection diode o\x0d\ 5. microwave heating, noise or vibration. Focus on checking the microwave system, such as high-voltage diodes, high-voltage transformers, high-voltage capacitors, bi-directional diodes, magnetron. \x0d\ 6. Slow microwave heating, fire than before significantly reduced this fault is usually the magnetron aging, a few is the power control selector switch or power relay contacts are bad. \x0d\ 7. Barbecue does not heat Check the grill for AC220V power supply. If the supply turtle is normal, replace the barbecue tube; if there is no supply voltage, check the barbecue control circuit, such as barbecue temperature limiter protector, barbecue t switch (some mechanical control microwave oven is set in the fire control, foot device), for computer-controlled microwave ovens. Also check the grill relay and drive transistors and other components. \x0d\ 8, after turning on the inner liner fire F In the case of confirming that the user does not use metal utensils, check whether the mica sheet is burnt, the inner liner is too humid. \x0d\ 9. Start or stop button malfunctioning \x0d\ Generally seen in computer-controlled microwave ovens, check the membrane switch o\x0d\ 10. Computerized microwave ovens power up with display, but do not start Check the door switch and the switch on the panel. \x0d\ Tips: Individual models have special operating methods, such as: Wheelock microwave ovens powered on the first time to start, you must first open / close the door once, the purpose is to prevent users from not into the food on the start of the machine caused by dry burning; Sharp microwave ovens powered on the first time you must first press the "cancel key", the other keys to play a role. \x0d\ 11. Sometimes do not start, sometimes automatic switching function, buzzer error \x0d\ Measure the CPU's +5V, reset, clock oscillation pin voltage, replace the crystal o\x0d\ 12. tray does not run \x0d\ In the case of confirming that the spindle and the track is normal, check the synchronization of the tray motor and the motor supply voltage. \x0d\ 13. Fan motor does not run \x0d\ Check fan motor and power supply. \x0d\ 14. After opening the oven door, the oven tray motor still turns \x0d\ Computer-controlled microwave ovens, check the main relay and control transistor on the computer board; mechanically controlled microwave ovens, check the oven door switch. \x0d\ 15. mechanical microwave oven heating does not stop Check whether the timer motor is damaged, whether the timer knob spindle is stuck with the panel, whether the timer motor power supply is normal. \x0d\ Tips: 1. Timer motor has AC220V, AC50V, A (surplus) v points. \x0d\ 2. The timer motor is powered by the fan motor tap. Damage to the fan motor will also cause the timer motor to stop. \x0d\\\x0d\ 3. Maintenance Precautions \x0d\ Because excessive microwaves are harmful to the human body, microwave oven instruction manuals are generally labeled "Do not expose yourself to radiation emitted by the microwave generator or other microwave-conducting components". This requires maintenance to do the following three points: 1. open the microwave oven shell on the power test or repair before, should be unplugged from the high-voltage transformer primary a plug; 2. check the non-door failure and overhaul of non-door switch parts, do not unscrew, disassemble the door switch fixing screws; 3. repair the auto-start faulty machine, do not open the door under the circumstances of the test machine. \x0d\ microwave system of any device are working in high voltage or high current state. Parts that may be exposed to voltages above 250V during disassembly are: magnetron, high voltage transformer, high voltage diode, high voltage diode, high voltage fuse. It is therefore quite dangerous to service or approach these circuits while the microwave oven is in operation, and it is prohibited to test the voltage in the high voltage circuits, including the filament voltage of the magnetron. \x0d\ After the microwave oven stops working, the charging in the high voltage capacitor will continue for 30s or longer period of time, therefore, when replacing or testing the high voltage microwave system devices, the high voltage capacitor should be discharged first. Improper installation of the magnetron and oven door can lead to microwave leakage and overloading. \x0d\\\x0d\\ General troubleshooting of non-heating: \x0d\ is generally categorized into low-voltage faults and high-voltage faults resulting in non-heating. \x0d\ 1, low voltage failure is generally due to low voltage power supply line problems, the formation of 220V AC voltage is not sent to the high voltage transformer or frequency conversion board, and then the high voltage localization does not work to provoke not heating. Low-voltage localized mostly due to timer damage (mechanical microwave ovens) or computer board relay damage (computer-type microwave ovens), there are a small number of microwave ovens due to microswitch. \x0d\ 2, high-voltage failure is generally caused by three major components, high-voltage diode, magnetron, high-voltage transformer. Because of the brand and the use of different length of time, the three major components of the damage chances also differ, Granz microwave oven does not heat most of the high-pressure diode short-circuit caused by time speculation, within 8 years of the microwave oven does not heat the diode short-circuit caused by the proportion of more than 8 years outside the microwave oven does not heat the magnetron caused by most of the non-heating. And there is a very small part of the high-voltage transformer damage caused by microwave ovens do not heat, such causes are less.