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  • Appliances Repair in MD

  • Appliances Repair in MD

      Troubleshooting/Diagnosing

      No Lights or Power, Unit seems Dead First check is the main fuse of the unit. On countertop units, you will need to take the shell off. The fuse will be close to where the cord comes through into the unit. OTR units, this main fuse is usually behind the control panel or possibly behind the vent. Usually the fuse is obvious if blown, otherwise test with an OHM meter, if open, replace fuse.

  • Appliances Repair in MD

  • Appliances Repair in MD
    Some brands will also have a thermal cut-off fuse in the incoming voltage line to the control board. Older Maytags and Samsungs have this fuse in it. This thermostat looking fuse is usually above the oven cavity somewhere under the outside shell. Sometimes you can get to it through the vent of OTR models. Test with an OHM meter, replace if open.

  • Appliances Repair in MD

  • Appliances Repair in MD
    Lights come on, but can not program unit, Touchpad dead If you have a stuck key or non-responsive key, most of the time you will have to replace the keypad for this microwave oven repair. If your keypad is connected to your control board by a flat ribbon wire, try disconnecting it and clean the silver contacts with an ordinary pencil eraser. After cleaning, plug it back in and try it. If it doesn’t fix it, replace the keypad unit. Some units actually have keypad tests to confirm your diagnosis of a bad key.

  • Appliances Repair in MD

  • Appliances Repair in MD
    If your keypad and control is the same unit, replace that unit. Another note, unlike stove/oven keypads and controls, most microwaves do not have error codes or tests to distinguish whether it is truely the keypad or control. Most of the time, it is the keypad that needs replacing, but a small percentage of the time it can be the control. Check the tech sheet if they can point you to the right part.

  • Appliances Repair in MD

  • Appliances Repair in MD
    Microwave Runs, but no Heat OK, get ready, this micrwave oven repair can take some time. This is where you must be able to read a wiring diagram and do some “live” checks on parts. First easy check is to make sure power is coming off your control board at the MW relay. Make sure of the wires and test here, if you have 120 volts at this point, you have ruled out a lot of parts that could be the problem. You have now ruled out any switch problems, control board problems, or a thermostat or 2.

  • Appliances Repair in MD

  • Appliances Repair in MD
    If you do not have power from that MW relay on the control board, you must trace the wiring back to see if the proper voltage is going through your switches, any thermostats, and arriving at your control board. Your wiring diagram on your sheet will show you where and what to test. Below is a general switch test troubleshooting guide.

  • Appliances Repair in MD
  • Appliances Repair in MD
    If the proper voltage is coming into your control board and you are not getting voltage at the MW relay, then you need to replace the control board. If voltage is interupted by a thermostat or switch from your testing to the control board, then replace that part.

  • Appliances Repair in MD
  • Appliances Repair in MD
    Now, testing from the MW relay on to your transformer, high voltage capacitor, magnetron, and diode. Do not do any voltage reading from the secondary side of the transformer on, this can be a deadly microwave oven repair if you do not follow directions. This can result in electrocution and the “blowing-up” of your voltmeter, only do OHM testing with the power off and the capacitor discharged. Someplace in this circuit, usually before the transformer, you will have another thermostat to test. It is usually mounted on the magnetron. Do a quick OHM test to see if it is open or closed.

  • Appliances Repair in MD
  • Appliances Repair in MD
    Now to test either the transformer, high voltage capicitor, magnetron, and diode, you must test each part separately. A good rule of thumb, if your capacitor is bad, change the diode also. Another note, if you are working on an OTR model and you have determined to be one of these “heating” circuit parts, you can not test these parts until you take the unit down.

  • Appliances Repair in MD
  • Appliances Repair in MD
    If you don’t have the parts with you and you have to order them, order the magnetron, capacitor and diode and you will have a 90% chance of solving the problem. If it is an older microwave, order the thermostat also, most times you can return un-used, un-opened parts. Check with your parts supplier. This way you only have to take the unit down once.

  • Appliances Repair in MD
  • Appliances Repair in MD
    To test these parts, scroll down this page and you will see a chart with component tests. Follow the instructions to find which part(s) are defective in your microwave oven repair.

    Microwave Runs, Heats, but turntable does not move This is a fairly easy one. First, make sure the turntable coupler under the glass dish is not broken. Second, on the control board, find the turntable relay and test for voltage. Some turntable motors are 24 volts DC, so make sure your testing the correct voltage. If no voltage from the control board, then replace the control board. Otherwise head towards the turntable motor.

  • Appliances Repair in MD
  • Appliances Repair in MD
    On OTR models, you can get to the motor by un-screwing the bottom panel on the microwave. On countertop models, there will either be a knockout or screw on access panel. Check for voltage at the motor. If no voltage, check the wiring back towards the control. If voltage, then replace the turntable motor. The component list below also shows how to test a turntable motor.
    Appliances Repair in MD
    Appliances Repair in MD
    Microwave is arcing If you see arcing or sparking inside a microwave, turn unit off immediately. Arcing can be caused by having something metal in the oven cavity touching a side, an oven shelf is touching the side of the cavity, an oven shelf support has broken, microwave waveguide, or bad magnetron.
    Appliances Repair in MD
    Appliances Repair in MD
    If your microwave has a shelf in it, and you do not use it, keep it out. If one of the shelf supports breaks or comes out, the microwave will arc where the support was. You will have to sand the spot down, paint with appliance paint and re-install support. If the shelf shifts on the support and touches the side it will arc.
    Appliances Repair in MD
    Appliances Repair in MD
    Your magnetron waveguide will either come out of the top, or side of the oven cavity. Some will have a stirrer in it(mostly top waveguides) with a panel over, or just a cardboard type cover over it. Over time, the stirrer cover can become warped from the heat which will expose the stirrer’s metal shaft which will then cause sparking. These covers and stirrers come in a kit and can be replaced from inside the oven cavity.
    Appliances Repair in MD
    Your cover over a side waveguide is coated with a substance on it, and overtime this coating can come off from the heat and moisture in the microwave. These waveguide covers are very easy to replace from inside the oven cavity. Touch up any paint that may have chipped or come off because of the arcing.
    Appliances Repair in MD
    If your waveguide cover and/or stirrer are all OK, then the spark is coming from your magnetron. The antenna on your magnetrom has overheated and burned, sending the microwaves out at the wrong angle. If you catch this microwave oven repair early enough, you can usually get by with just replacing the magnetron. If the arcing has caused servere damage inside the waveguide, you will need a new microwave.
    Appliances Repair in MD
    Waveguides are not replaceable and most you can barely see into them, let alone sand and re-paint. In this case of microwave oven repair, when you remove the magnetron, you will see the burned antenna, or your magnetron will fail the test below.
    Appliances Repair in MD
    Microwave Vent Hood is not working This microwave oven repair is only for over the range(OTR) models. First, with microwave still installed, gain access to the control board and check for voltage from the fan relay. If you are not getting voltage from the fan relay on the control board, and your display says fan is on, then you need a new control board.
    Appliances Repair in MD
    If voltage is present and the wiring that you can see looks good, then you will have to take the unit down and test for voltage at the fan itself. If the voltage is present there, then test the motor itself and/or start capacitor for the motor. The fan motor assembly will slide out of the top of the unit after you take it down and unscrew 2 screws. Below, in the list of component testing, you will see how to test the motor and start capacitor.
    Appliances Repair in MD
    Microwave Stove Light not Working Again, this microwave oven repair is for OTR models. If you know your light bulbs are good and your display is telling you that they should be on, check the light relay on your control board. If no voltage is found at that relay, then replace the control board. Otherwise your problem is in the light socket, wiring, or wire connectors. You can get to all of that by unscrewing 6-8 screws under the unit and taking the bottom panel off.
    Appliances Repair in MD
    Microwave overheats and keeps turning off All microwaves have some sort of a cooling fan to help keep the magnetron and controls at a tolerable level. Most OTR models will usually use the vent motor for the cooling fan also. Countertop units have a small fan behind the control panel somewhere. Either way, if the cooling fan is not working and heat builds up, it is going to open a thermostat. On some makes, this thermostat might re-set itself as soon as the temperature cools down. Other makes, you will have to replace the thermostat or fuse.
    Appliances Repair in MD
    If this is your microwave oven repair problem, you will need to check the operation of the fan. Below in the component testing chart, you will see how to test the fan. Also, if possible, make sure the fan is not obstructed somehow and not turning. Also check your fan relay at your control board for voltage, if no voltage, replace control board. This fan should come on at the same time any cooking starts.

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