Sửa chữa lò vi ba

 

Dù là bạn đang sử dụng lò viba kiểu để bàn (countertop) hay kiểu đặt ngầm, (over the range, OTR), việc sửa chữa lò vi ba luôn là một công việc nguy hiểm nếu bạn không đủ kiến thức chuyên môn nhất định. Một trong những bộ phận chủ yếu của mạch đun nóng (heating circuit) là hộp tụ điện (capacitor) có thể duy trì điện thế lên tới 20,000 volt. Có thể làm bạn bị giật bắn người (that can definitely kill you), vậy nên bạn phải hết sức cẩn thận khi xem xét dò tìm (diagnosing) có tiếp chạm với các bộ phận bên trong lò vi ba.

Sửa chữa lò vi ba là chẩn đoán một trong những loại thiết bị nhà bếp phức tạp hơn thông thường mà bạn có thể phải động đến. Các hãng sản xuất khác nhau nhưng cấu tạo bên trong đều gần như nhau (pretty much the same on the inside) và được giải quyết (work off) với cùng một kỹ năng chẩn đoán giống nhau (same diagnostic skills). Cái rất thiết yếu (a must) để sửa chữa lò vi ba là tài liệu kỹ thuật (tech sheet) thường được nhét đâu đó trong thân lò, nó giúp rất nhiều cho bạn tránh được những chuyện mò mẫm trong khi chẩn đoán.

Over the range microwave’s(OTR) tech sheet will either be hidden behind the vent in a crevice or behind the console panel. Countertops and most built-in microwaves have the tech sheet in an envelope after you take the outside shell off.

Most microwaves have an electronic control and digital display. Even with having an electronic control, most microwaves do not have error codes to help you with microwave oven repair. Knowing how to diagnose problems will be your key. At this time, we have a very short list of error codes at the following link.

Microwave Oven Error Codes

Common Problems & Troubleshooting

Problems

First we will list some of the more common problems you will encounter in microwave oven repair. Then we will get into the troubleshooting and diagnosing of the part(s).

    No Lights or Power, Unit seems Dead The voltage to the unit is good.

    Lights come on, but can not program unit, Touchpad dead

    Microwave Runs, but no Heat Turntable rotates, acts like it is heating but doesn’t. This is the big one, many possibilities.

    Microwave Runs, Heats, but turntable does not move

    Microwave is arcing

    Microwave Vent Hood is not working Over The Range(OTR) Models.

    Microwave Stove Light not Working OTR models, light bulbs good.

    Microwave overheats and keeps turning off

These problems are common to all types of microwaves.

Before getting to the testing for microwave oven repair, here is some warnings. Your microwave is hooked to a 120 volt power source which can shock you, extreme care should be followed. When testing a microwave, always have a glass of water inside the microwave, you should never operate a microwave empty. Damage will occur to unit. Also read the following warning.

Below find a generic parts location on a microwave. This particular model is a OTR model. The parts might not be in the exact location, but will give you a general area where they are supposed to be. This will help in microwave oven repair parts testing.

Technical Question-Click Here
Schedule/Request Service-Click Here
Microwave Oven Error Codes List
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.

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.

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.

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.

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.

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.

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.

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.

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. 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.

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.

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.

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.

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.

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.

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.

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. 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.

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.

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.

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.

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.

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.

Technical Question-Click Here
Schedule/Request Service-Click Here
Microwave Oven Error Codes List

Component Testing

Below find the component testing charts. Just find the component you want to test and follow the instructions. This chart is a generic parts tests and should be good for most parts you need to test in your microwave oven repair.


Microwave Oven Maintenance & Tips

Below is a short list of maintenance & tips, hopefully to alleviate some microwave oven repair.

Keep your Microwave Clean We mention this all the time, but keeping both the inside and outside will help prevent microwave oven repair. Certain food splatters left inside the cavity can eventually eat away the paint and start to arc. Spills under the turntable tray will start rust and possibly holes and arcs.

Clean your Filters Often This is for OTR models. We do not think these models vent as well as a regular range hood. A dirty filter will make it vent even worse. If you cook a lot of fried foods or even do a lot of steaming, make sure to clean your vents on a regular basis. Most are stainless steel and can be put in your dishwasher.

Also check and clean your outgoing vent filter behind your top vent. Not all OTR models have one, but if this one gets clogged, it will also lessen your venting capabilities.

Owner’s Manual & Installation Instructions Read these manuals, they offer a vast amount of information about operating your unit, and may even prevent some microwave oven repair. The installation manual, follow to a “T” to insure proper safety of your unit.

Microwave Error Codes List
Technical Question-Click Here
Schedule/Request Service-Click Here
Comment about this Webpage or Site-Click Here
From Microwave Oven Repair to Cooking Overview
Return to Brunswick GA Appliance Repairs

 

ENGLISH ORIGINAL


Whether you are working on a countertop (kiểu để bàn) or over the range(kiểu đặt ngầm, OTR) model, microwave oven repair can be extremely dangerous. One of the main components in the heating circuit, called the capacitor, can store over 20,000 volts of electricity. That can definitely kill you, so extreme caution must be taken when diagnosing your microwave oven. (Cẩn thận với bộ phận tích điện capacitor, có thể phóng điệnvới điiện thế 20 nghìn volt!)

Microwave oven repair can be one of the more complicated kitchen appliance you will have to repair. All brands are pretty much the same on the inside and work off the same diagnostic skills to repair. One thing that is a must for microwave repair is the “tech sheet”. Tucked away somewhere in the unit, it will help you fix the unit.

Over the range microwave’s(OTR) tech sheet will either be hidden behind the vent in a crevice or behind the console panel. Countertops and most built-in microwaves have the tech sheet in an envelope after you take the outside shell off.

Most microwaves have an electronic control and digital display. Even with having an electronic control, most microwaves do not have error codes to help you with microwave oven repair. Knowing how to diagnose problems will be your key. At this time, we have a very short list of error codes at the following link.

Microwave Oven Error Codes

Common Problems & Troubleshooting

Problems

First we will list some of the more common problems you will encounter in microwave oven repair. Then we will get into the troubleshooting and diagnosing of the part(s).

    No Lights or Power, Unit seems Dead The voltage to the unit is good.

    Lights come on, but can not program unit, Touchpad dead

    Microwave Runs, but no Heat Turntable rotates, acts like it is heating but doesn’t. This is the big one, many possibilities.

    Microwave Runs, Heats, but turntable does not move

    Microwave is arcing

    Microwave Vent Hood is not working Over The Range(OTR) Models.

    Microwave Stove Light not Working OTR models, light bulbs good.

    Microwave overheats and keeps turning off

These problems are common to all types of microwaves.

Before getting to the testing for microwave oven repair, here is some warnings. Your microwave is hooked to a 120 volt power source which can shock you, extreme care should be followed. When testing a microwave, always have a glass of water inside the microwave, you should never operate a microwave empty. Damage will occur to unit. Also read the following warning.

Below find a generic parts location on a microwave. This particular model is a OTR model. The parts might not be in the exact location, but will give you a general area where they are supposed to be. This will help in microwave oven repair parts testing.

Technical Question-Click Here
Schedule/Request Service-Click Here
Microwave Oven Error Codes List
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.

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.

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.

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.

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.

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.

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.

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.

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. 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.

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.

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.

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.

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.

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.

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.

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. 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.

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.

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.

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.

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.

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.

Technical Question-Click Here
Schedule/Request Service-Click Here
Microwave Oven Error Codes List

Component Testing

Below find the component testing charts. Just find the component you want to test and follow the instructions. This chart is a generic parts tests and should be good for most parts you need to test in your microwave oven repair.


Microwave Oven Maintenance & Tips

Below is a short list of maintenance & tips, hopefully to alleviate some microwave oven repair.

Keep your Microwave Clean We mention this all the time, but keeping both the inside and outside will help prevent microwave oven repair. Certain food splatters left inside the cavity can eventually eat away the paint and start to arc. Spills under the turntable tray will start rust and possibly holes and arcs.

Clean your Filters Often This is for OTR models. We do not think these models vent as well as a regular range hood. A dirty filter will make it vent even worse. If you cook a lot of fried foods or even do a lot of steaming, make sure to clean your vents on a regular basis. Most are stainless steel and can be put in your dishwasher.

Also check and clean your outgoing vent filter behind your top vent. Not all OTR models have one, but if this one gets clogged, it will also lessen your venting capabilities.

Owner’s Manual & Installation Instructions Read these manuals, they offer a vast amount of information about operating your unit, and may even prevent some microwave oven repair. The installation manual, follow to a “T” to insure proper safety of your unit.

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