We therefore recommend you leave the appliance to discharge for at least one day before taking it apart. If the noise persists, identify and rectify the source starting with the motor drive followed by the drive coupler, magnetron, and so on. This liquid could have ended up finding its way to the motor, causing it to leak electricity and trip the circuit breaker. Microwave is making a loud humming sound when cooking. If so, then you need to replace the magnetron because it's just pulling too much power. Disconnect all the electrical connectors and place the multimeter's two probes on the microswitches' terminals. Carrying out repairs on a microwave oven requires a very careful and safety conscious approach. And diode went bad again. If the HV diode is short-circuiting or leaking electricity, your appliance may make a loud noise and could end up blowing the fuse or tripping the circuit. As it happens, I have replaced the microwave with a Samsung one as the Sainsburies one happened to be just over a year old - so out of warranty. It will normally be fitted just after the point where the power lead enters. The interference suppressor is needed to protect the appliance from possible electronic malfunctions. I have checked the magnetron, it reads less than one ohm reading both terminals. If you read the same voltage as the battery, then the diode is bad and needs to be replaced. I have seen some of the higher rated Microwaves blowing the CL01s, and working using CL04-12 diodes only rated at a little higher, 450 mAmps. I have been working on a maytag o/r microwave. I replaced with a universal diode. I tested the diode and there is no continuity in either direction - i presume blown. If either the capacitor of transformer short out, the Microwave will draw over 30 amps very quickly blowing your fuse. I disassembled the microwave and tested HV diode, capacitor, transformer, and magnetron. Microwave ovens produce powerful electrical discharges that can potentially be fatal. Open up your microwave's outer casing and locate the door latch microswitches. If your microwave is making an unusual or loud humming noise, you may have a problem with the high voltage diode. Repairing internal faults is dangerous and requires special training and tools. High voltage diode in a microwave keeps blowing. The capacitor or diode may be bad. We recommend taking a look at the socket to see whether it might have melted. If you do not obtain any values, this confirms there is no electrical leak. I pulled the diode out and it reads 17 ohms both directions. However, as the wattage of the newer Microwaves gets higher, the HV diode must meet the requirements of the circuit to work without breaking down too early, or failing entirely. When the diode fails, it is often visibly burned out. If the diode burns out, the magn... etron won’t receive enough voltage to operate, preventing the microwave from heating. However, make sure you follow the safety instructions detailed above if you decide to do this. Even when unplugged, the capacitor inside the microwave oven can still produce power electrical discharges. Checked the circuit (I am an engineer, so no worries about high voltages), found a failed diode. Access to the diode will require removal of the cabinet. Plug in a lamp at the same outlet and see if it gets power. You can test a new diode with the same procedure of creating a series circuit and confirm that there is an appropriate drop in voltage. The cooling fan might have died or lost its effectiveness. The capacitor stores energy then releases it in an amplified state. Someone gave me an Emerson MW8118SL that is about 1 1/2 years old and I figured I'd give it a shot. The more common of the 2 parts to fail is the capacitor. I get its power back on by replacing the "flame sensor" which GE named. The door safety latch mechanism on your microwave contains several small switches. You might be running too many appliances on the same circuit, or the oven could be defective. if you don't obtain a value, the capacitor is defective. 3-9 amps = transformer is good. CHas your microwave recently begun tripping the power in your house and you don't understand why? The diode also has the job of increasing the voltage that powers the heart of the microwave, the magnetron. This could also cause the microwave's fuse to blow or trip your circuit. Upon exam i found bad hv diode. You can also check whether the motor is leaking electricity or not by placing one of the multimeter's probes (still in ohmmeter mode) on the appliance's metal chassis and the other on one of the motor's terminals. To verify the result, also check to see if there is any current leaking anywhere. To enable all features please, YAF.NET © 2003-2020, Yet Another Forum.NET. Originaly I heard a popping sound and then the microwave got louder and quit heating food. One end of the transformer connects directly to the appliance's ground. by Charlie (Pennsylvania) I do some appliance repair, but never really tried to fix a microwave. If you do, this component will need to be replaced. If the resistance stays high, the diode is stuck open and needs to be replaced. Problem is in HV circuit. Place your meter leads on the ends of the diode and you should see a quick rise and fall on your meter. NOTE: Before you test your diode, make sure your microwave is unplugged, and that you discharge the microwave's capacitor. Remove and test with an ohmmeter. When the live end of the secondary HV winding is positive, the diode is forward biased, shorting the magnetron. The main fuse was blown. One end of it connects to the capacitor and the other to your microwave's ground. Welcome Guest! Secure payment Credit Card, PayPal and bankwire, Fast delivery International home delivery, Money-back guarantee Free returns : 30 days to change your mind. Furthermore, as a microwave’s capacitors can hold a lethal charge even when unplugged, it can be dangerous to test things like the high voltage diode without properly discharging them first. When you first open the microwave up, make sure you short circuit the capacitor using a pair of electrically insulated pliers (with the appliance unplugged from the mains of course). You can check the motor using a multimeter in ohmmeter mode. A three years old microwave stopped heating up. Interference suppressors can sometimes blow, causing them to short-circuit and trip the power or blow the fuses. Disconnect your appliance from the power source; you will be handling electrical components. An object might have gotten lodged in the fan and stopped it from rotating. Whether or not the microwave has a dedicated circuit, the microwave may be tripping the breaker because there’s something wrong the the microwave itself that’s causing it to pull too much electrical juice. You should get a value in one of the two positions of each switch (i.e. Checked the fuse and didn't see continuity, so I replaced it. Place a cup of water in the microwave. I replaced the diode put it back together turned it on and I heard a pop the microwave was loud for a second or two and then got quiet(like only a fan is running) still not heating. It basically the thermo cut-off sensor. And if it blows the fuse for your kitchen, there also is a likely cause for that. If your microwave’s ceramic fuse keeps blowing and it needs investigation, this is something that is definitely best left to a professional. Check in your breaker box to see if the breaker that keeps tripping has the word “Microwave” next to it. Next, disconnect all the connectors and place the multimeter's two probes (in ohmmeter mode) on the motor's terminals to test for continuity (it should normally give a reading of between 6 and 11 kilo ohms). Make absolutely sure you remember to follow the safety instructions provided at the beginning of this article. If it's defective, the appliance will make a loud noise when operating and end up blowing its fuse or even tripping your electricity. If any of the door latch hooks is broken or any of the switches is faulty, the appliance will not operate. Question: So, if the diode is blown, will it cause the internal fuse to blow when ever the door is closed? We also recommend wearing a pair of electrically insulated gloves to ensure you are able to work in complete safety. Important: do not forget to follow the safety instructions provided at the beginning of this troubleshooting guide. The capacitor check good. The diode converts the A/C power output of the transformer to D/C, doubling the voltage to nearly 5,000 volts. You should not obtain any values. To take the measurement, disconnect the magnetron's connectors and place the multimeter's probes on its terminals. Before checking and testing this component, carefully read the safety instructions provided at the beginning of this article. The high voltage diode is made up of a stack of eight diodes. You can test the door latch using a multimeter in ohmmeter mode, first with the door in its open position and then with it closed. You can contact us via e-mail if you have any questions ! Before testing this component, check your multimeter is definitely set to "Ohms Ω" and make sure you've discharged the capacitor. If it keeps throwing the breaker, though, you should check why. If you get a continuity reading (a value is displayed), this means the motor is faulty. Just make sure the ratings of the capacitor and diode are correct (use a generic replacement microwave oven HV diode and a microwave HV capacitor with a uF rating within 10% or so of the old one and at least equal working voltage). Replacing the HV diode is normally not difficult, and they are quite cheap to purchase. It is a two terminal device that may look like a tiny resistor or diode and may be mounted on a metal header fastened with a couple of screws. It does not heat. One end of it connects to the capacitor and the other to your microwave's ground. Model: 65568601991: Brand: Kenmore: Age: 5 - 10 years: Previous Topic Next Topic: bpamerick1 #1 Posted : Tuesday, November 2, 2010 1:54:20 PM(UTC) Rank: Member. ... Have a microwave amana that keeps blowing internal fuses. Just as most homes are equipped with fuses or circuit breakers, microwave ovens also have fuses that short out or blow in the event of an overload. If any of the timer's electrical contacts are damaged, this could cause the circuit to trip or a fuse to blow. Make absolutely sure you carefully follow the safety instructions provided at the beginning of this troubleshooting guide. Under 3 amps the problem is in the LV circuit. Here are some possible causes of repeated blown fuses, from the easiest to fix at home to the hardest. There is a risk of getting electrocuted. If not, the problem is more likely a circuit breaker than the oven. 10-14amps = all is good. Next, locate and remove the high voltage diode in order to test it for continuity. Replacing the HV diode is normally not difficult, and they are quite cheap to purchase. If you can't unplug your microwave, the socket and plug may have fused together, in which case you'll need to turn of the electricity supply and try applying a little force to get them to come apart. How to test a microwave high voltage diode with a multimeter. Make sure, when you replace the diode, that the point of the triangle on the diode (the schematic symbol) points toward chassis ground. Microwave then heated for about 3 min. Due to this stacking, the HV diode cannot be checked with a multimeter. However, you don't need to use the exact combined part - which may be very expensive or difficult to obtain. Begin by disconnecting the microwave from the electricity supply and discharging the capacitor. Everything except the diode cheked out OK. To do this, place the tip of one of the multimeter's probes on the outer metal casing of the magnetron and the other probe on one of its connection terminals. Frequently when a transformer goes bad it will also smoke or burn up. Reads open to each terminal to ground. Whether it is shorted or open, a defective diode will most likely show some sign of defect. You risk electrocuting yourself if you neglect to do this. It is powered by the electrical current supplied to the appliance and emits electromagnetic waves. I replaced the HV diode and it still made the loud buzzing sound. I then replaced the hv capacitor just in case because i … A diode or rectifier should cause a voltage drop, in this circumstance one of approximately 3 volts. If the transformer is defective, the appliance will make a lot of noise and could trip the circuit or blow a fuse. If the HV diode is short-circuiting or leaking electricity, your appliance may make a loud noise and could end up blowing the fuse or tripping the circuit. Your meter needs to be using a 9-volt battery. Do not test the capacitor unless you've first disconnected it from the electricity supply and discharged it by short-circuiting it with an electrically insulated tool. If it has an electrical leak, it will trip the circuit breaker. If your microwave constantly trips the breaker, check to be sure the microwave has a its own dedicated circuit. Repeat the operation for each terminal. If not, then that most likely means your microwave does not have a dedicated circuit. I used 9v battery testing method with cheapy multimeter, and a Fluke 87V to test the HV diode. Your Microwave Keeps Blowing Fuses Check the door switch as described above. You can check the condition of this component, but ensure you pay strict attention to the safety instructions when doing so. If the oven goes a long time between blown fuses, this might be the reason. Microwaves use a diode to convert incoming A/C power to the D/C power that the microwave needs. Both methods show the diode is okay. There is only 1 diode in a microwave. When he investigates your problem, he’s likely to find one of these 7 common causes of microwave failure: #1: Diode Burn-Out. Originaly I heard a popping sound and then the microwave got louder and quit heating food. The magnetron is more likely to fail than the capacitor. Attach your amp probe to the line splitter, plug in and run microwave 10-20 seconds. Here, we're going to help you work out where this problem is coming from so you can resolve it. If the value you obtain is around zero, the magnetron is working correctly and is not the source of the fault. Microwave oven cavity paint, waveguide cover mica sheets, and even some replacement doors are available from the parts suppliers listed at the end of this document. This high voltage powers the magnetron to heat the food. To make a microwave quieter, first try the inbuilt settings such as refreshing of sensors, hard resetting, and engaging of the silent mode. Test to see if the microwave is malfunctioning WARNING We recommend adopting a very cautious and safety-conscious approach if you need to take your microwave apart at any point. door open or door closed).Make absolutely sure you remember to follow the safety instructions provided at the beginning of this article. Anyone attempting to repair their own Microwave must remember that they can hurt or kill you. The microwave could have faulty switches in the door, a bad magnetron, faulty internal circuitry (such as a diode, capacitor, or transistor), or a blown fuse. Discharge the capacitor as described earlier in the article, and then test it by removing the leads and setting the VOM to RX100. Your microwave may be tripping the power due to an issue with its electricity supply. Replace the magnetron if your tests prove it to be defective. If so, it has a dedicated circuit. Your microwave's timer will be either mechanical or electronic in design. If your microwave oven blows a fuse, there are a couple possible causes. “What is the function of the high voltage diode in a microwave oven?” This is a half-wave, voltage doubling rectifier circuit. Carry out this same test on each of the capacitor's terminals. Emerson microwave blows fuses. The magnetron sits inside the microwave's outer casing. The turntable motor enables your microwave to cook food uniformly. Otherwise, you run the risk of getting electrocuted. Without high voltage testing equipment and some skill in using it, you can only test each component for a short by measuring the resistance to ground. Do not try to repair a microwave … Defective diodes will usually emit an electrical burning smell, signifying its defectiveness. Options. Remove the cabinet and discharge the high voltage capacitor to avoid getting an electrical shock. If this happens, your microwave will not be able operate. In simpler terms, this means the microwave has its own circuit breaker. If the door switches are new and the capacitor has been replaced, that really only leaves the magnetron. Never test and use a multimeter on the appliance with it still plugged into the mains. Complaint was no heat. The voltages on either the magnetron, transformer or capacitor may be too high for the multimeter to cope with. Tyler Z., Home Appliance Technician Troubleshooting guides for Microwave ovens, Your Microwave Is Tripping Breaker On Startup, Heating element, inserted electrical element, All spare parts for steam iron / steam generator iron, All spare parts for refrigerator, freezer, All spare parts for coffee maker, espresso, All spare parts for smartphone, mobile phone, Appliance Troubleshooting Guide: Home Appliance Repair Guides & Diagnostics, There is an issue with the electricity supply to the appliance, The high voltage diode is short-circuiting, Microwave Light Not Working: 4 Main Causes of a Microwave Light Bulb Not Working, Noisy Microwave Oven: 6 Common Causes of a Microwave Making Unusual Noises, Microwave Tripping Breaker: 9 Reasons Why a Microwave Trips Breaker on Startup, Microwave Not Heating Food: 5 Common Causes of a Microwave Not Heating Properly, Microwave Oven Not Turning on: 10 Common Causes of a Microwave Not Working, Microwave Oven Turntable Not Turning: 5 Causes of a Broken Microwave Turntable, Microwave Sparking: the 4 Most Common Causes of Sparks in a Microwave Oven. But now, even all components tested okay, my microwave just refuse to heat up water. The diode and capacitor do not usually fail in this manner, so I suspect you have an issue with the transformer or the magnetron. Replaced the diode, the microwave worked for about a week, then showed the same problem. It's possible that when you put your food in the microwave, liquid of some kind ran under the turntable and you then forgot to clean it up. Disconnect the connectors from the capacitor then place the tips of your multimeter's probes (in ohmmeter mode) on each of the capacitor's terminals. Groups: Registered Joined: 11/2/2010(UTC) Posts: 6. microwave diode keeps blowing?? You can also check whether the capacitor has an electrical leak or not. Microwave Diode: Isolate the capacitor and check for resistance on the most sensitive scale. The high voltage transformer amplifies the electric current so that the magnetron can operate. To do this, place one of the multimeter's probes on one of the capacitor's terminals and the other probe on the appliance's metal frame/casing. Then locate the turntable motor, which will be underneath the appliance. Call in an electrician if necessary. Never test these components without first disconnecting the appliance from the electricity supply and discharging the capacitor. This component is part of the high voltage circuit along with the capacitor and the magnetron. I saw 250V 20A inscribed on the old fuse, so I got a pack of these to replace it.. After replacing the fuse, the microwave powers on and I was able to set the time on the clock, use the cooktop light, etc. I have a GE JVM1540DM2BB over the range microwave which keeps blowing a fuse. Contact us ! Disconnect the wires to the magnetron and run a cycle to see if the microwave will run without blowing the fuse. SOS Accessoire cannot be held responsible for any accidents that may occur. 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