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    How to test a magnetron used in microwaves ?

    How to test a magnetron used in microwaves ?

    what are the symptoms of bad magnetron ? And, can they be repaired ?

    thanks

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    Re: How to test a magnetron used in microwaves ?

    :!:
    magnetron.gif

    BE CAREFUL BEFORE TOUCHING THE MAGNETRON AND BE SURE THE MAINS IS DISCONNECTED AND ALL CAPACITORS DISCHARGED
    Unplug all the wires from magnetron carefully and take note for the connections (as the wiring is critical).
    1. Now with the multimeter set on LOWEST resistance range check both terminals resistance, should be less than ONE Ohm (Ω).
    2. Now select the meter's HIGHEST resistance range and check from any terminal (infact the filament connections) to the metal housing resistance , DO NOT TOUCH any probe test terminals at this point. No resistance should be shown, if there is any, the Magnetron is BAD.
    Hope it is helpful.


    2 members found this post helpful.

    •   Alt8th November 2011, 09:14

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    Re: How to test a magnetron used in microwaves ?

    Quote Originally Posted by Raza View Post
    :!:
    magnetron.gif

    BE CAREFUL BEFORE TOUCHING THE MAGNETRON AND BE SURE THE MAINS IS DISCONNECTED AND ALL CAPACITORS DISCHARGED
    Unplug all the wires from magnetron carefully and take note for the connections (as the wiring is critical).
    1. Now with the multimeter set on LOWEST resistance range check both terminals resistance, should be less than ONE Ohm (Ω).
    2. Now select the meter's HIGHEST resistance range and check from any terminal (infact the filament connections) to the metal housing resistance , DO NOT TOUCH any probe test terminals at this point. No resistance should be shown, if there is any, the Magnetron is BAD.
    Hope it is helpful.
    thanks

    How to test a Pakistani Tube-light Choke (both electronics choke or ballast & normal one found in older tube lights) ?

    thanks



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    Re: How to test a magnetron used in microwaves ?

    Raza's tests are for the filament and leakage and are good. However, if you want to test it for efficiency there is no way other than to power it up and detect the RF leaving the antenna port. This is a highly specialized job and unless you have the equipment to do it, I strongly suggest you do not try. The voltages and RF radiation from a magnetron are absolutely lethal and both can result in instant death.
    Also beware that they MUST be force cooled while operating and they contain strong magnets.

    Brian.


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    Re: How to test a magnetron used in microwaves ?

    Quote Originally Posted by betwixt View Post
    Raza's tests are for the filament and leakage and are good. However, if you want to test it for efficiency there is no way other than to power it up and detect the RF leaving the antenna port. This is a highly specialized job and unless you have the equipment to do it, I strongly suggest you do not try. The voltages and RF radiation from a magnetron are absolutely lethal and both can result in instant death.
    Also beware that they MUST be force cooled while operating and they contain strong magnets.

    Brian.
    Don't worry , tell me about the equipment required to carry on this specialized job .... How to detect the RF leaving & antenna Port ?

    thanks

    ---------- Post added at 14:49 ---------- Previous post was at 14:24 ----------

    Quote Originally Posted by munzir View Post
    Don't worry , tell me about the equipment required to carry on this specialized job .... How to detect the RF leaving & antenna Port ?

    thanks
    If the keypad of the microwave oven not working, then what to do ?

    Can we fix them ? If yes, then, how to do that ?

    thanks



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    Re: How to test a magnetron used in microwaves ?

    To test the magnetron RF power requires very specialized test equipment but it sounds like you are trying to repair a microwave oven. The RF testing kit would cost about as much as 500 new ovens so unless you are doing this as a business I would stop right now!

    What exactly are you trying to do? If you have a microwave oven with a non-functioning keypad it is very unlikely to be anything to do with the magnetron. What fault symptoms do you see.

    Brian.


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    Re: How to test a magnetron used in microwaves ?

    Quote Originally Posted by betwixt View Post
    To test the magnetron RF power requires very specialized test equipment but it sounds like you are trying to repair a microwave oven. The RF testing kit would cost about as much as 500 new ovens so unless you are doing this as a business I would stop right now!

    What exactly are you trying to do? If you have a microwave oven with a non-functioning keypad it is very unlikely to be anything to do with the magnetron. What fault symptoms do you see.

    Brian.
    i was asking about two different things & i asked two different questions .........

    kindly, answer both of them ......... about keypad & also about RF Testing KIT ..........

    thaxXx though



    •   Alt8th November 2011, 16:19

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    Re: How to test a magnetron used in microwaves ?

    RF testing kit is real expensive tool and needs special skill to use without getting harmed from the High Voltage or the RF power, as both are dangerous to the life.
    On the keyboard question, there are many possibilities to this defect. You are needed to put here some symptoms to guess the fault.
    May be just DC supply Bad (5 volts to MC) or may be some gating circuit integrated with microcontroller or some ROW and COLUMN generator (still a lot of possibilities)

    My test procedure in post #2 was just for a beginner. As to test Magnetron in Live Circuit is a specialized job.


    1 members found this post helpful.

    •   Alt8th November 2011, 16:28

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    Re: How to test a magnetron used in microwaves ?

    Quote Originally Posted by Raza View Post
    RF testing kit is real expensive tool and needs special skill to use without getting harmed from the High Voltage or the RF power, as both are dangerous to the life.
    On the keyboard question, there are many possibilities to this defect. You are needed to put here some symptoms to guess the fault.
    May be just DC supply Bad (5 volts to MC) or may be some gating circuit integrated with microcontroller or some ROW and COLUMN generator (still a lot of possibilities)

    My test procedure in post #2 was just for a beginner. As to test Magnetron in Live Circuit is a specialized job.
    Would you explain these faults & their remedies ? please

    As you said in your above mentioned beautiful post :

    " May be just DC supply Bad (5 volts to MC) or may be some gating circuit integrated with microcontroller or some ROW and COLUMN generator (still a lot of possibilities)."

    1) If DC supply gone bad, then, what are the symptoms of it & how to resolve the issue ? From where the DC supply is originating & where its terminating ?

    2) What about ROW & Column Generator ? what are the symptoms of bad ROW & Column Generator & how to resolve the issue ?

    3) Gating circuit integrated with microcontroller, if its gone bad then, what are the symptoms of it & how to resolve the issue ?

    thanks a lot though



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    Re: How to test a magnetron used in microwaves ?

    Symptom 1. Check the supply voltage for their proper limits and if not correct them.
    Symptom 2. Any gating circuit can be tested for proper working with a Logic gates IC tester.
    Symptom 3. For testing Digital special circuits a Skilled person must have the knowledge of those.
    If the supply is gone bad has different effects of different situation. If regulated supply is BAD and gone to its highest level caused by a short circuited series regulator, the all ICs may had (repeat may had gone) bad but if gone bad to no supply voltage then you have to check the culprit of failure.



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    Re: How to test a magnetron used in microwaves ?

    let us be very clear on this subject.....as far as testing the mag in a mw goes-the check of continuity between filament pins to case(sc mag-scrap buy a replacement magnetron) will isolate a faulty mag....be very careful about removing the filament wires as the hi voltage capacitor may still be charged...another way to locate a faulty mag is to listen to the mw as you start a cook cycle and if there is no buzz as the mag cuts in (which quickly dissappears)or a constant growl the mag is faulty and needs changing(can also be caused by a sc diode followed by fuse blowing or smoking ht transformer-or sc capacitor or the asm rectifier sc which usually blows fuses straight away.Other faults ,capacitor oc or lo in value can affect the mag as well.most capacitors have an internal bleed resistor fitted which is meant to discharge it but you cant rely on it-safety first-manually discharge the cap...as far as keypads go if they dont work it may simply be an interlock fault or cleaning of the ribbon cable where it enters the display board ...if the membrane keypad has failed throw it away and buy a new one.
    do not carry out repairs to any microwave unless you know exactly what you are doing............ just as an example heres a service manual for one ......
    Last edited by sheldonstv; 8th November 2011 at 18:45.



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    Last edited by ALERTLINKS; 8th November 2011 at 21:39.



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    Re: How to test a magnetron used in microwaves ?

    Experimenting with magnetrons can be spectacular, although it is definitely in the high-risk category.

    There are websites telling about doing such experiments, and the pitfalls one must watch out for, and safeguards which one should exercise.

    Similarly with testing a magnetron.



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    Re: How to test a magnetron used in microwaves ?

    Quote Originally Posted by Raza View Post
    Symptom 1. Check the supply voltage for their proper limits and if not correct them.
    Symptom 2. Any gating circuit can be tested for proper working with a Logic gates IC tester.
    Symptom 3. For testing Digital special circuits a Skilled person must have the knowledge of those.
    If the supply is gone bad has different effects of different situation. If regulated supply is BAD and gone to its highest level caused by a short circuited series regulator, the all ICs may had (repeat may had gone) bad but if gone bad to no supply voltage then you have to check the culprit of failure.
    what do you mean by that " Check the supply voltage for their proper limits and if not correct them ? "

    what should be the range of the supply voltage & what should be the proper limits & how to correct them ?

    thank$$



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    Re: How to test a magnetron used in microwaves ?

    Munzir, these are basic things that you must fully understand if you are to attempt repairs on electronic equipment. I am sorry if we seem to insult you but the questions you ask suggest to us that you are not yet ready to handle such dangerous equipment. We do not mean you harm but it seems you could put your life at risk by not heeding our warnings and none of us want that responsibility.

    Magnetron radiation is invisible but extremely dangerous, simply pointing the waveguide at someone can kill them. They can also be seriously and irreversibly injured by waves reflecting off other objects. There is also the more obvious danger of the very high voltages and sufficient currents to casue serious burns or fibrilation. Before considering repairs on this kind of equipment you should have a thorough understanding of electronics, control systems and RF.

    Brian.



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    Re: How to test a magnetron used in microwaves ?

    Ok, thanks Brian !

    But you can easily explain these to me, regarding keypad (or its associated issues)

    what do you mean by that " Check the supply voltage for their proper limits and if not correct them ? "

    what should be the range of the supply voltage & what should be the proper limits & how to correct them ?

    thank$$



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    Re: How to test a magnetron used in microwaves ?

    Almost certainly there is a microprocessor driving the display and keys to enter the time/power/start/stop and so on. The microprocessor requires a power source and this is one of the first things to suspect as being faulty if the unit doesn't work. The microprocessor is probably a generic type but programmed at the factory and stamped with a custom part number, without knowing what it's real part number is you can't tell what the supply to it should be. Typically the supply voltage is 3.3V or 5V but if the display is flourescent it may also need a low AC voltage for the filament and a high voltage (> 20V) for the display segments. Without a service manual it is almost impossible to say what the voltage should be and one model will be different to the next.

    Brian



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    Re: How to test a magnetron used in microwaves ?

    Munzir,
    Testing for the supply limit means if the supply for a Microcontroller you must know whether it is 5 volts or what. If it is 5 volts, it must be be in the limit from 4.75 volts to 5.25 volts. If it is low the MC will not work and if it is more than 5.25 it may damage the MC. So is the case in other supplies like 12 volts and so on.
    I hope these basic things are in your knowledge.



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    Re: How to test a magnetron used in microwaves ?

    Quote Originally Posted by betwixt View Post
    Almost certainly there is a microprocessor driving the display and keys to enter the time/power/start/stop and so on. The microprocessor requires a power source and this is one of the first things to suspect as being faulty if the unit doesn't work. The microprocessor is probably a generic type but programmed at the factory and stamped with a custom part number, without knowing what it's real part number is you can't tell what the supply to it should be. Typically the supply voltage is 3.3V or 5V but if the display is flourescent it may also need a low AC voltage for the filament and a high voltage (> 20V) for the display segments. Without a service manual it is almost impossible to say what the voltage should be and one model will be different to the next.

    Brian
    But if the power is al-right .... and the buttons have the problem , can we clean or replace the buttons or the whole keypad of the microwave ?

    thanks



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    Re: How to test a magnetron used in microwaves ?

    It depends upon the Keyboard style and availability at the same time. There are still many things to make sure for proper working. If there are coders and decoders for the Row_Column circuitry, you have to be sure about them for proper working.



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