Microwave Oven Repair in Nairobi
Microwave Oven Repair services in Nairobi Kenya. Is your microwave oven broken? Is it not turning on? Not heating, broken glass, broken hotplate? We fix microwave ovens in Nairobi. Call us for service.
MICROWAVE OVEN MEMBRANE SWITCH
If the touch pads on your microwave oven do not respond but the display lights up, the problem is most likely with the membrane switch. This component, which is more commonly referred to as the touch pad, is actually a series of soft touch electrical switches. It is usually made up of two layers of a thin Mylar plastic with a conductive material on the inner surfaces. A formed gap between the two surfaces will separate the conductive coatings until pressure is applied by the user, making the two surfaces come in contact. When the two conductive surfaces contact each other, an electrical circuit is completed to provide an input signal to the control board. With repeated use, the conductive coating will eventually wear out and be unable to make a good enough contact to send the signal to the control board. To access the membrane switch you will need to unplug the unit and remove the cabinet. The membrane switch is often attached to the control panel and is usually connected to the electronic control board with a flat ribbon style connector. Check the connection first and if it appears okay, then you can test the membrane switch for continuity with a multi-meter. There should only be a few ohms of resistance for each touch pad when pressed. To perform this test you will require the matrix layout of the membrane switch which should be contained in the electrical schematic.
MICROWAVE OVEN CONTROL BOARD
If the touch pads on your microwave oven do not respond but the display lights up, the problem may be with the control board. The control board generates a low voltage that is supplied to the membrane switch. When a pad is depressed, the voltage signal is switched back to the control board. The control board receives these input signals from the membrane switch or touch pad and uses these commands to turn on output relays that control the various components of the microwave, such as the turntable motor and the magnetron. If the control board does not generate the low voltage signal, or if it does not sense the input signals from the membrane switch, then no output functions will occur. If you have verified that the membrane switch is fine and the connection to the control board is okay, then the control board may be defective. Replacement will require disconnecting the power and removal of the cabinet and control assembly.
MICROWAVE OVEN DRIVE MOTOR
If the turntable on your microwave is making an unusual noise, the problem may be with the drive motor. Most microwave ovens with a glass tray use a motor driven coupler to turn the tray or a roller guide. The motor is typically located below the floor of the oven, and access will need to be through the bottom. The motor is normally held in place with a retaining screw and will have two wires attached to it as well. If the motor is making a grinding noise it will need to be replaced.
MICROWAVE OVEN MAGNETRON
If your microwave is making an unusual or loud humming noise, you may have a problem with the magnetron. This component is part of the high voltage circuit and provides the microwaves that generate the heat. If the magnetron is defective, it may cause a loud humming or buzzing noise. Access to the magnetron will require removal of the cabinet. Disconnect the power and also discharge the high voltage capacitor to prevent an electrical shock. You can then locate the magnetron and disconnect the two attached wires and the mounting screws to remove it. You should also check the high voltage diode to verify that it is not shorted before condemning the magnetron.
MICROWAVE OVEN DRIVE COUPLER
If your microwave is making an unusual noise, the problem may be with the drive coupler for the turn tray. Most microwave ovens with a round glass tray use a motor driven coupler to rotate the tray on a roller guide. Some models that use a rectangular tray will have a drive coupler that has an offset center roller to drive the tray guide from side to side. For either style, remove the tray and roller guide from the oven and then inspect the coupler. Some models may require you to remove the motor from the bottom before you can pull the coupler off of the motor. The coupler normally has a D shaped opening that fits tightly onto the motor shaft. If it is cracked or worn it may become noisy and will need to be replaced. If you have to remove the bottom cover, you will need to disconnect power from the appliance first.
MICROWAVE OVEN ROLLER GUIDE
If your microwave is making an unusual noise when the turn tray is rotating, the problem may be with the roller guide under the tray. Some microwave ovens with a round glass tray use a motor driven coupler to turn the roller guide. The roller guide is used to support the tray and to engage the rotating coupler. Remove the tray and then inspect the roller guide. Check the hub to see if it engages the coupler securely and also the outer rollers for signs of cracks or damage. If there are signs of wear or damage, it should be replaced. Other models may just use the roller guide to support the tray, however the roller wheels may be damaged or worn and causing an unusual noise. If the roller guide appears to be normal, then check the coupler for damage.
MICROWAVE OVEN HIGH VOLTAGE DIODE
If your microwave is making an unusual or loud humming noise, you may have a problem with the high voltage diode. This component is part of the high voltage circuit along with the capacitor and the magnetron. Access to the diode will require removal of the cabinet. Disconnect the power and also discharge the high voltage capacitor to prevent an electrical shock. You can then locate the diode and use a multi-meter to check for continuity. Reverse the meter leads to check for continuity in the opposite direction. There should be continuity in only one direction and if not, it will have to be replaced.
MICROWAVE OVEN COOLING FAN
If your microwave is making an unusual noise, the problem may be with the cooling fan. The cooling fan is located inside the cabinet and is used to cool the magnetron. Disconnect the power and then remove the cover and locate the fan assembly. Inspect the housing for any foreign objects that may contact the fan blades and then check the
MICROWAVE OVEN DOOR INTERLOCK SWITCH
If your microwave oven doesn’t appear to shut off when the door is open, you may have a problem with the door switch. The door switches, often referred to as interlock switches, provide power to the various components of the microwave. They are designed to interrupt the power when the door is open. In certain situations when an interlock switch fails, the interior light, fan motor, or stirrer motor may continue to operate after the microwave oven door is opened. The magnetron will not operate because of a failsafe monitor switch. The interlock switches are located inside the cabinet and are activated by hooks or latches on the door. Unplug the unit and remove the cabinet. The interlock switches will have wires attached to the terminals marked common (C) and normally open (NO). You can check the switches for continuity using a multi-meter. The closed door will depress the actuator button on the switch; you should see continuity between these terminals. When the door is open there should be no continuity, and if there is the switch needs to be replaced.
MICROWAVE OVEN SMART BOARD
If your microwave oven doesn’t shut off until the door is opened, you may have a problem with the control board. The control board, sometimes referred to as the Smart Board, powers the relays that control the various functions of the microwave. If the control is defective it may not shut off a relay when the function is complete, and then opening the door to interrupt the power to the control would be the only way to terminate the cycle. If you have this symptom, the control board may be at fault. Unplug the unit and remove the cabinet. If the relays are not part of the control board, you should check the output terminals on them for continuity first. There shouldn’t be continuity when the relay is not powered. If the relays check okay, then the control board is likely defective.
MICROWAVE OVEN HIGH VOLTAGE DIODE
If your microwave oven doesn’t heat, you may have a problem with the high voltage diode or rectifier. This component helps provide the high voltage that powers the magnetron. The high voltage diode is located near the magnetron and the high voltage capacitor, so access will require removal of the cabinet. Disconnect the power and also discharge the high voltage capacitor to prevent an electrical shock. You can then test the diode for continuity with a multi-meter. Diodes are polarity specific and you should see low resistance with the meter leads in one direction and higher resistance when the meter leads are reversed. Most multi-meters will have a special setting for diodes or rectifiers. If the high voltage diode shows low resistance in both directions or shows no continuity at all, then it will need to be replaced. If you find the high voltage diode tests okay, then you will need to determine whether power is being supplied to the circuit. This is a high voltage circuit and further testing should only be performed by a qualified technician.
MICROWAVE OVEN DOOR SWITCH
If your microwave oven doesn’t heat, you may have a problem with a door switch. The door switches, often referred to as interlock switches, provide power to the various components in the microwave when the door is in a closed position, and interrupt power when the door is open. Sometimes it is possible that when an interlock switch fails, the fan motor and or stirrer motor may continue to operate but the magnetron won’t. The interlock switches are located inside the cabinet and are activated by hooks or latches on the door. Unplug the unit and remove the cabinet. The interlock switches will have wires attached to the terminals marked common (C) and normally open (NO). Check the switches for continuity using a multi-meter. With the actuator button depressed, you should see continuity between these terminals. If there is no continuity the switch will need to be replaced. You should also verify that the door hooks properly engage the switch actuator when the door is closed and adjust if necessary.
MICROWAVE OVEN MAGNETRON
If your microwave oven doesn’t heat, you may have a problem with the magnetron. This component is part of the high voltage circuit and provides the microwaves that generate the heat. If the magnetron is defective, the unit may blow a fuse, or you may still have all other functions operating normally. Access to the magnetron will require removal of the cabinet. Disconnect the power and discharge the high voltage capacitor to prevent an electrical shock. You can then locate the magnetron and disconnect the two attached wires. Attach the leads from a multi-meter to the magnetron terminals and check for continuity. There should be only 2-3 ohms of resistance between these terminals. If there is no continuity, then the magnetron will need to be replaced. Also, check for continuity between both terminals and the grounded outer case of the magnetron. If there is any continuity between either of the terminals and ground, the magnetron will need to be replaced. If the continuity checks do not reveal any defects, then live voltage tests may be required and should be referred to a qualified person.
MICROWAVE OVEN DOOR LATCH LEVER OR BUTTON
If the door on your microwave oven won’t open, you may have a problem with the door latch lever. The door latch lever assembly usually consists of a paddle or button that either pivots downward or pushes into the control panel. It then contacts the door latch assembly and releases the door hooks to allow you to open the door. If the pivot or lever portion is broken, then the door hooks cannot be lifted to release the door. Unplug the unit and remove the cover to access the door latch lever. You may also need to remove the control panel to gain better access. Remove the broken piece and insert the new part into the pivot openings. On models that use a push button style, release the retaining tabs and install the new part making sure that the return spring is installed correctly.
MICROWAVE OVEN DRIVE MOTOR
If the turntable on your microwave doesn’t rotate or is making a grinding noise, the problem may be with the drive motor. Most microwave ovens with a round glass tray use a motor driven coupler to turn the tray or a roller guide. The motor is typically located below the floor of the oven, and access will need to be through the bottom. The motor is normally held in place with a retaining screw and will have two wires attached to it as well. If the motor is making a grinding noise it will need to be replaced. If the motor doesn’t turn, you can check for voltage or continuity with a multi-meter. With the power disconnected and the bottom panel removed, locate the motor and unplug the wires to the motor. Measure for continuity at the motor terminals or at the wire harness that is still attached to the motor. If there is no continuity, the motor will need to be replaced. For voltage checks, you will need to plug the unit into a live outlet and therefore this check should only be performed by a qualified person.
MICROWAVE OVEN COUPLER
If the turntable on your microwave doesn’t rotate, the problem may be with the drive coupler. Most microwave ovens with a round glass tray use a motor driven coupler to turn the tray on a roller guide. Some models that use a rectangular tray will use a drive coupler that has an offset center roller to drive the tray guide from side to side. For either style, remove the tray and roller guide from the oven and then inspect the coupler. Most models will have a three sided coupler that will just pull off of the motor shaft. Some models may require that you remove the motor from the bottom before you can pull the coupler off of the motor. The coupler normally has a D shaped opening that fits tightly onto the motor shaft and if it is cracked or worn it will need to be replaced. If you have to remove the bottom cover, you will need to disconnect power from the appliance first.
MICROWAVE OVEN ROLLER GUIDE
If the turntable on your microwave doesn’t rotate, the problem may be with the roller guide under the tray. Some microwave ovens with a round glass tray use a motor driven coupler to turn the roller guide that the tray rests on. The roller guide is used to support the tray and to engage the rotating coupler. Remove the tray and then inspect the roller guide. Check the hub to see if it engages the coupler securely and also the outer rollers for signs of cracks or damage. If there are signs of wear or damage, it should be replaced. If the roller guide appears to be normal, then check the coupler for damage.
MICROWAVE OVEN CHARCOAL FILTER
If the exhaust fan on your over-the-range microwave is not working, the problem may simply be the charcoal filter. The charcoal filter is used to trap and absorb cooking smells when no external vent system is used. Over time, the charcoal filter will become clogged and restrict the air flow. The charcoal filter is normally located behind the exhaust air outlet grill. You can typically detach the grill by removing some retaining screws and then remove and replace the charcoal filter which may also have a spring clip to hold it in place. Replace the charcoal filter on a regular basis to maintain a good airflow. You should also check the condition of the primary grease filter as well.
MICROWAVE OVEN GREASE FILTER
If the exhaust fan on your over-the-range microwave is not working, the problem may simply be the grease filter. The grease filter or filters are used to trap cooking oils and fats to prevent contamination of the exhaust system. With normal use, the grease filters will become clogged and restrict the air flow. Normally, the grease filters are located on the bottom of the microwave and are held in place with spring clips or tabs for easy removal. Regular cleaning of the grease filters in hot water and detergent will help maintain proper airflow, however, if the filters are very dirty or damaged they should be replaced. If an external exhaust system is not used, you should also inspect the internal charcoal filter.
MICROWAVE OVEN DAMPER ASSEMBLY
If the exhaust fan on your over-the-range microwave does not appear to be working, the problem may be with the damper assembly. If you are connected to an external exhaust system, the damper is used to prevent unwanted outside air from entering the room. The damper is basically a metal or plastic flapper that closes off the exhaust duct when the fan is not running, and opens when the fan turns on. The damper may have a spring assisted flapper or it may rely on gravity to keep it closed when the fan is not in use. If the damper does not open easily or completely, then the airflow may not be sufficient to remove steam or cooking smells. The damper is located at the exhaust outlet of the microwave and removal from the wall or cabinets may be necessary. Verify that no foreign objects or the exhaust duct connector are interfering with the damper. Replace the damper if it appears to be damaged or does not open and close easily. When re-installing the vent connector, make sure there is no interference with the damper.
MICROWAVE OVEN FAN MOTOR
If the exhaust fan on your over-the-range microwave does not appear to be working, the problem may be with the fan motor. The fan motor is located at the top rear of the microwave and exhausts the air into the duct system or re-circulates into the room through the charcoal filter depending on the installation. If the fan motor does not turn on when selected, you will need to disconnect the power and remove the unit from the wall or cabinet to service. Remove the cover and locate the fan motor. Rotate the motor by hand. If the motor will not turn, it needs to be replaced. If the motor turns freely, you can check the motor for continuity with a multi-meter and if no continuity is found, you will need to replace the motor. If the motor does show continuity, the next step would be to check for power to the fan motor. This is a live voltage test and should only be performed by a qualified person. If the correct voltage is available, then the motor is likely defective. If no voltage is detected, the problem may be with the wiring or the electronic control board.
MICROWAVE OVEN DOOR SWITCH
If your microwave oven won’t start, you may have a problem with a door switch. The door switches, often referred to as primary or secondary interlock switches, provide power to the various components in the microwave when the door is in a closed position, and interrupt power when the door is open. Sometimes it is possible that when a door switch fails, the display and controls may appear normal, but the oven won’t operate. The interlock switches are located inside the cabinet and are activated by hooks or latches on the door. Unplug the unit and remove the cabinet. The interlock switches will have wires attached to the terminals that are marked common (C) and normally open (NO). You can check the switches for continuity using a multi-meter. With the actuator button depressed, you should see continuity between these terminals. If there is no continuity the switch will need to be replaced. You should also verify that the door hooks properly engage the switch actuator when the door is closed and adjust or replace it if necessary.
MICROWAVE OVEN CERAMIC FUSE
If your microwave oven won’t turn on and the display is blank, the problem may be the ceramic fuse. The ceramic fuse is used to protect the components of the microwave oven if you have a severe power fluctuation or if there is a critical fault with one of the internal components. When the fuse fails, power is interrupted to the controls of the microwave and it will become nonfunctional. The ceramic fuse is located inside of the cabinet near the entry point of the power cord. Remember to unplug the cord before attempting any repairs. You can check the fuse for continuity with a multi-meter. If the fuse failed for no apparent reason, check the major components such as the magnetron, high voltage diode, capacitor and transformer, and associated wire terminals, before changing the fuse. If the fuse failed when opening or closing the door, check for a shorted door switch, monitor switch, or improper adjustment of the door latch assembly. Use only the manufacturers’ suggested part number when replacing this fuse.
MICROWAVE OVEN THERMAL FUSE OR CUT OUT
If your microwave oven won’t turn on, you may have a problem with the thermal cut-out. Microwave ovens use one or more thermal cut-outs, sometimes called thermal fuses, to protect the oven from overheating. They are located inside of the cabinet, often near the oven cavity or the magnetron. If the thermal cut- out fails, power is interrupted to the controls or to the control outputs. Unplug the unit and remove the cabinet. Locate the thermal fuse or cut-out and remove the wires from the terminals. Check for continuity with a multi-meter and replace the part if no continuity is shown. Verify that the cooling fan is functional and that the air flow is not restricted.
MICROWAVE OVEN DOOR LATCH ASSEMBLY
If your microwave oven won’t turn on, you may have a problem with the door latch assembly. The door latch assembly usually consists of two hooks that protrude from the door and fit into the door switch holder that is mounted to the frame of the microwave. The hooks will contact the door switches to provide power to the controls and also, latch onto the holder to keep the door closed. The latch assembly is normally made of plastic and usually has a spring attached to provide downward tension to keep the hooks engaged. If either of the hooks is broken or does not have any spring tension, the switches may not be engaged. If this happens, the oven won’t turn on and you may need to replace the assembly. Unplug the unit and remove the inner door panel to access the door latch. The inner panel is normally attached by plastic tangs and caution should be used to remove it.
MICROWAVE OVEN DOOR LATCH ASSEMBLY
If the door on your microwave oven doesn’t appear to close properly, you may have a problem with the door latch assembly. The door latch assembly usually consists of two hooks that protrude from the door and fit into the door switch holder that is mounted onto the frame of the microwave. The hooks will contact the door switches to provide power to the controls and also latch onto the holder to keep the door closed. The latch assembly is normally made of plastic and usually has a spring attached to provide downward tension to keep the hooks engaged. If either of the hooks is broken or does not have any spring tension, you may need to replace the assembly. Unplug the unit and remove the inner door panel to access the door latch. The inner panel is normally attached by plastic tangs and caution should be used to remove it.
MICROWAVE OVEN TORSION SPRINGS
If the door on your microwave oven doesn’t appear to close properly, you may have a broken torsion spring. On microwaves that have a door that opens downward, torsion springs are used to keep it closed. There are normally a left and right side spring and they are often different sizes. If your door won’t stay closed, one of the springs may have broken. Unplug the unit and remove the inner and outer door panels to access the torsion springs that are located at the bottom front of the door. Depending on the model involved, the panels may be held in place with screws from the inside, bottom, or sides. Use caution as the outer glass door may be heavy.