How to test the Microwave Oven's HV Diode
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- Опубликовано: 6 июн 2024
- Many viewers have been asking how to test the microwave oven's HV Diode. Since Ohm meters and Diode Checkers cannot test these Diodes, I will show you a quick and simple alternative to Test the HV Diode.
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Thank you! Very helpful with the suggestion to use the 9 volt battery because the high-voltage diode has such a big current drop across it. Also great to see exactly what the voltage drop across your diode is so that I know what to expect!
Nice and clear teaching. Straight foward.
Thank you sir. I was testing the components in a furnace electronic air cleaner which has been weak, and now unresponsive even when the test button was pressed and ran into two diodes like this, which I first concluded to be open. Using the 9V battery test, 5.7 volts through the battery each, so they are good. Found the capacitor which is in parallel with the transformer secondary (11nF, 4kVAC) had a split in it.
NTP Vlogs are their channels. share repair microwave oven Panasonic inverter, fan steam brother share learning mutual experience. your channel is very useful. remember to register your channel. thanks.
best explanation i've seen so far.. thanks for the video
That was why I though my HV Diode had been dead by using ohm test. Later I knew that there must be a Voltage load to test a *HV Diode* ... Thanks for sharing anyway.
your presentation is very clear , i understand all ,thank you very much.
Good information, thanks for sharing!
It worked thanks had another diode from parts I savaged. Voltage in the bad one was only about half volt lower than the good one.Tried it, works like a charm. :-)
Thank you for the video. Very helpful.
Thanks for the video. Was wondering why the new diode had the same infinite resistance both directions as my old one. You kept me from buying yet another diode thinking they were bad.
Glad it helped
Cool video shot, thanks for sharing it with us, well done :)
thanks .... helps a lot. good presentation!
Nice video. I was able to conclusively test my diode.
Thank you for sharing this great video.
I am impressed with your creativity! You are connecting the voltmeter in series with the battery and the diode. You are measuring voltage drop on the voltmeter.
in theory you can deduct that voltage (6.7V) from 9V (the battery) to come up with the voltage drop on the diode (2.3V). In reality, since the voltmeter's resistance is very high, few megaohms, the flowing current is just few microamps. So the calculated voltage drop is out of the working range of the diode.
To measure the voltage drop of the diode, connect a 100 Ohm, or so, resistor in series with the diode and the battery. Then measure the voltage on the diode (between the cathode and anode).
yes indeed would be interesting to see the volt drop with a 1 kohm resistor as a load. It is not a high resistance diode as such as it is probable a diode stack maybe 3 off 0.7 volt diodes in series to share the high reverse emf Tthis would give about 2.1 volts drop
Thanks for your, really learn a lot
Great video. I’m subscribing to this channel.
Thank you for showing this it’s very cool how you can do it , it would be even better if we can sea the all connections or small diagram how yo connect that battery.
Thanks for sharing dryer repair..
thank you very educative.
Thank you for this video. 2 quick questions. If the reading on volt meter is higher than 9 is there a problem then? If it is still good, I have another issue, I put a new capacitor in, and the diode is good. Microwave works but fan and doesnt work. What could this be? Fan spins freely. Thank you
If the manufacturer does not offer capacitor or diode parts for the machine can they be purchase as generic parts?
Nice job
Good one, did not know that one.
thanks nicely explained
The steps to troubleshoot the diode is excellent, but the 9V connection and the DVM connection are not fully visible.
Thanks for your vids..... Sorted mine out.... Turned out to be a blown fuse on the HT side
alright, now show me how to test the magnetron. sweet video, very thorough.
WhirlPool microwave MH1150XMB3. I replaced the magnetron and diode, however when I started the unit, it ran about 10 seconds, blew a fuse (?), and had a burning smell. Does the microwave have low and high circuits? Can I test both these circuits and the circuit that fails the test has the bad wiring? Can you tell me where to test these circuits?
Thanks, any help would be greatly appreciated
Jim
Hi Mr.fix it goodday!im so proud of you,to give a info n help those people need to fix their prob.especially for electrical prob.also me,im asking n help too about my concern for my Genset,?Bosco Generator,2000 watt,How can i fix it n how it prevent the prob.having a overload sign light on?but the engine still running in good condition,even i did not put or connect any unit can be use?,hopefully u can give me a time to discuss for what the solution of my prob.be solve..im really appreciated it. Tnks..Godbless...
Thank you for putting this together for everyone. It's very helpful. It'd be great if your "intro" wasn't almost 90 seconds long. (The actual content is only 8 minutes long, so your "intro" is 15% of your total video. For a TV episode--of course, which I know this is not--that is the equivalent of an 8 minute intro.)
well at least you can fast forward like it was DVR
Too funny.
thank you bro.
Thanks sir.great.
Can you use just a multimeter if the meter has a ohm range of 0 - 20M Ohm
Thank you
Sir, i have some issues with my microwave oven. I have replaced the busted fuse with the same rating as with the old one but for some reason, the new one was also blown up. When I have replaced it and plugged the microwave, everything goes fine. But when I started cooking, the microwave will start to blow the fuse up.
Sir Does magnetron has a polarity or if I connect in reverse will it blow up and is there any way to find its polarity
Thank You!!!!!!!!!
Don't mean to be picky but in electronics class, I was taught that the opposite of the cathode was called an "an ode" instead of "a node", otherwise you did very well!
When my microwave turns on it blows the microwave fuse right away the capacitor check fine what will the problem be.
Thanks
Not Always. The HV Diode is usually the cause as to why the Microwave does not heat the contents. The HV Capacitor will cause the HV Diode to fail when it shorts out internally. This is why it is a good idea to check both the Diode and the Capacitor, Although the diodes are large in size, they can only handle around 1/2 A (500 mA). They are designed to block between 6KV and 15KV when the polarity is reversed. and will eventually breakdown on there own. -MrFixit
? Do you mean rectify ac waveform supply that reverses polarity
MR fix it ... I have being following some of your microwave related tutorias with great results.
Now , I wonder if you.d take upon the challenge of showing us how to install dial controls on a microwave that came with a digital but hard to find control pannel.
I have a vagge idea of how to do it , but would sure apreciate seing someone who knows how to perform such a hack.
Sir my microwave oven is not heating may you tell me what are the probable faults in that so that i may check all the points
Does this test works with all microwave HV Diode, Thanks.
(sigh) I really wish I knew that forever ago. Thanks
Why didn’t you connect the diode the other way…. To test in the diode setting you check, both ends switching the terminals. One will come through with voltage. The other way will come through with OL. You only did one direction and saw the OL. I believe that’s how you check it with the diode function on the multimeter. I guess the point is you don’t need the battery, although that works too - when you have a diode test function on your multimeter like you do.
Can you please what caused the high voltage diode to short out explode
What would happen if you leave the diode not connected in your microwave.
Does the magnetron still fire microwaves?
Thank you nice video and info. please tell me that CAN WE REPLACE BAD MAGNETRON WITH GOOD ONE OF ANY MICROWAVE OVEN
The magnetron can be replaced but has to match the one in the microwave, however, buying a new Microwave is cheaper.
@@ESRepair thanks
Thanks for this great tutorial Sir. Just want to point out one thing. OL for ohms stands for Open loop or broken circuit. For volt reading OL means Over limit. Cheers
An "Open loop" is Over Limit on the Ohms scale.
Most instructive video - very cool [the intro tho, is way too long - jmo]. Kudos sir!
i have a sharp carousel micro, it has power to the digital screen and the light comes on. the turntable doesnt turn and ii dont hear any sound when i turn it on, no fan nothing what could it be?
My G.E. OTR microwave oven has an intermittent problem. It works for a few minutes, then it starts making a loud "CLACK-CLACK-CLACK-CLACK-CLACK" that sends the cats running from the kitchen at top speed. Last night, it did this after 4 minutes and then tripped the GFCI outlet. Can someone suggest the most likely faulty part?
Thanks
ty
I didn't understand what numbers represented a bad diode and what represented a good diode in a microwave oven. Could you explain? Obviously, I am a novice.
Sir my microwave oven is Amana there is display but it can't start please give suggestion thank you
Thank you sir
Is the HV Diode the most common thing to go out in a microwave?
Can we use a 1.5V torch cell (instead of 9 V dry cell) In which case may we expect a voltage drop of, say, about 0.5V across the diode?
You will see no voltage from 1.5V battery because the voltage drop on this diode is 2.8-3V. However you can use 12V battery from your car or simply use the battery charger .
what if the tester shows ~2-3v, not ~6v, meanwhile the diode drop is ~3 v. ? is it ok ? Thank you.
When testing microwave diode the multimeter connections are not clearly shown
Your're Welcome. -MrFixit
My fluke meter can test these accueately on the anode/diode test selction. Most multimeters that run off of a 9v naruarlyy can test hv caps normally without the extra external 9v. Just put it on dioide test. Put leads one direction. Flip them opposite direction. Done.
Hi , my microwave [ G.E. ] does not heat, and makes a loud hum [ and also sounds like its struggling a bit ] which is how you described a failed diode , but are those also the symptoms of a failed capacitor ? are they likely to fail together ? thanks, Will
not always, but usually it's one or the other. -MrFixit.
I have tested all the parts but everything seemd ok. My display didnl light up. Eventually i heated the microcontroller on the board with a heat gun and let it cool.After that - magic. At least for now :) Probably some connection was loose. The oven was in a balcony with rapid temperature changes when open the door at winter. Maybe this cause the bad connection. Thanks for the video !!
helpfull
Isn't common or always that the diode is connected to the negative side of the capacitor. I believe that the diode goes with the white wire on the cap.
Thanks for the video but i cant see your meter displays.
Turn your monitor on.
There is a lot of mis-information in the comments section of this vid. When you here a loud humming and the microwave produces no heat, the problem is typically a bad magnatron. Contrary to what is stated in the comments. The simplest way to determine the problem is with an amp meter. With the microwave turned on, if your current draw is 2 amps or less, you have a problem in the low voltage(120 volt) side of the microwave. This is typically a door switch or control board issue. If your current draw is 3 - 6 amps, it means the high voltage transformer and the capacitor are both good, and your problem is either the magnatron, or the high voltage diode(more times then not it is the magnatron). If your amp draw is 50 amps or something very high like that, its usually the capacitor bad. A typical properly functioning microwave will draw between 12 -16 amps, depending on house voltage and wattage of microwave,
That's all good and well, but you do not explain how to differentiate between a failed magnetron and diode. Therefore you have not answered the question.
There are a ton of videos that show you how to check the diode. Unlike a typical diode, for this high voltage diode you have to connect it in series with a 9 volt battery. Watching a video on it is a lot easier then trying to explain it. Having said that, I typically replace both the mag and the diode together, as the diode is a very low cost item, if it turns out the problem was a bad mag. For the sake of a $5.00 part I don't want to have to pull the microwave down and tear apart again.
Thanks, that makes sense.
+billy bob Would you please read my post at the top of this forum? I have taken several measurements in every possible configuration in an attempt to figure out why my fuse blows. I'm really not interested in replacing parts blindly as it can get expensive. Perhaps you can decipher things based on my test results. Thanks.
billy bob
hi there, I didn't get the results of reversing the orientation of the diode. When it drops to mv and fluctuate in the meter does that mean it's good? You just mentioned it's high resistance but what should be the result for a working diode? Thank you
The results is current only flows in one direction. Yes, If the diode show no current flow in the reversed direction then the Diode is good. Often times the meter would show millivolts due to natural leakage of the material that makes up the diode.
Thanks. Great video
where can i order a sharp carousel capacitor diode
Dear sir,
I have microwave oven.when it is on from quick start ,its sparking from magnatron.
this is magnatron fault or high voltage transformer fault.
please advice.
Saman(sri lanka)
Saman Wijeratne The magnetron will need replaced. Magnetrons have an insulator inside to prevent arcing of the high voltage has failed. -MrFixit
I had to give it thumb's up just because of the intro.
I have two comments:
1. Since you haven't shown all the connections, it's impossible to see exactly what you're measuring.
2. It makes a lot more sense to measure the current through the diode. It should be zero in one direction and high in the other. That tells you it's working, no matter what the voltage drop is.
You sound like you know what you're doing.
It was difficult to see what he was doing with his connections.
With a new 9 volt battery mine measures 1.42.
Flip it around and the volt meter says zero.
I'm wondering if 1.42 going through it is high enough to start the micro heating or if that needs to be higher and the diode is shot.
Here is my trouble, I hope you read it and tell me what I should do, and I want to tell you that you are such a kind guy.
In my case, I have tested the diode and it is bad, because the resistance is infinite from either one end to the other and vice versa.
Now, I like to ask you, why has the diode gotten bad?
And also please read the background of the trouble.
I also understand that the internal bleeding resistor of the capacitor is supposed to dissipate the charge when the oven is disconnected from the mains, but just the same repair persons should still take the caution of the routine discharge procedure before handling the capacitor…?
Background of the trouble.
I have replaced a busted capacitor of the following specs:
2100VAC 0.82mF +-4%
with one of these specs:
2100VAC 0.84mF +-3%.
The original trouble was that I started to use the oven one morning and it did not show any activity whatsoever.
As I had a similar trouble some months back and I fixed it by replacing the blown fuse, this time I did the same procedure but nothing occurred with the oven except a slight vibrating fart noise: no smell of burning, no visible sign of any burning, and the new fuse got blown up.
So I started reading about repairs of microwave ovens in the internet, and came to the conclusion that most likely the power capacitor is the culprit.
So I removed it and tested it, yes it is busted.
Next I bought the replacement capacitor as I described above, and installed it, what happened now?
The same thing happened as before: a slight vibrating fart noise, and the new fuse also got blown up, but no smell of burning, no visible sign of burning.
At this point I said to myself that I hope the new capacitor did not get busted now; but I have not removed it, not yet, to test it -- saying to myself that I had better do more reading in the internet.
My question is the following: if it is not the capacitor that is the culprit, what is the most likely candidate for the same trouble as before, i.e., what part(s) should be replaced?
Since I have a lot of time in my hand, and I also already now use another oven, so it is just a matter of some sort of adventure to fix it, and plus that with it fixed I will again have a reserved oven.
Hope you will draw from your years of experience and give me some tips, and I have not yet taken out the new capacitor to see whether it is also now busted -- what do you say, from your years of experience with microwave oven repairs?
Thanks a lot in advance, and also again for the massive information in your website.
Marius de Jess
mdejess(@)gmail.com
+Marius Dejess -- Since the original diode showed as open (no current path) in either direction, it failed as a fuse would, and probably for the same reason: excessive current being drawn. A shorted filter capacitor is the next cheapest suspect part, and would indeed pull way more current directly to ground than should be going across it, taking the fuse almost immediately.
If after replacing that big electrolytic (the polarity *was* right upon repair, right?) then you're pretty much down to either the magnetron or the HV transformer. If you're paying retail for parts, then replacing either of those parts can approach the cost of a whole new machine. If you're going to be doing lots of repairs on gear that runs HV, it wouldn't hurt to keep a spare power transformer or two around, with different ranges of outputs (or a Variac to control the input, thereby varying the output). Magnetrons are pretty specific as to the application, both electrically and physically.
As has been already pointed out, always discharge all leads/terminals to chassis ground with a "hot stick" -- I use a chopstick with a 100-ohm, 10-watt resistor heatshrunk to the side, one lead of the resistor to clip onto ground, and the other lead sticking out past the far end of the chopstick to touch to hot spots. A screwdriver with a tip you don't really care about can be used, too, as long as you've got the shaft of the tool well insulated. And keep your other hand in a back pocket as you do this -- no sense having your body, full of salt water, as the most direct path to ground.....
Hope this helps. And thanks for the OP's video. With the possible exception of a lack of explanation of just what *should* be seen in the voltage drop test to qualify as a good diode (which he covered in a replay soon after posting), the info is great for someone who has a modicum of common sense and an adventuresome spirit about fixing stuff inexpensively around the home that, without moving parts, may not be obvious to the average handyman.
Cheers & 73
Does anyone think a cut wire to the plug the microwave is plugged in will fry it ? Fuse is good
even on line I cant see them advertised.... anywhere.
how many volts does that diode hold? im going to use a high voltage transformer, but i think it wont be enought. help me
Many of these diodes can handle up to 12kV @ 500mA.
you have connected two digital multimeters but how is connected not clear
hi where can I get a Samsung microwave HV diode 2CL 4512 H44 from?
that sparking light coming from magnatron nozzle.
Ok, so if you have a voltage drop from 9v to 6.6 does that mean the diode is good or bad?
it means the diode is good. -MrFixit
@@ESRepair .......I think ESRepair and MrFixit are shorted !!! Both Butt welded together !
I just tested my diode with a new 9 volt battery and it shows about 4 volts one direction is that to low?
It seems good.
I have a problem with my microwave If the diode is connected to earth it will cut off the fuse but if the diode is not connected the fuse will not cut off and the microwave will not get hot why
Helpful video. Unfortunately, the HV diode was ok, so it's not going to be such an easy fix :(
I tested a micronde Diode. I found 536 in one side and - 536 in the other, what means please.?
536 What? If the diode is conducting in both directions then it is bad and needs replaced. The diode should only conduct in ONE Direction
Can you tell me if there is no heating and a loud humming noise what that is a sign of?
Either the HV Capacitor is shorted, the HV Diode is Shorted, or the The HV Transformer is shorted.
sounds promising then if it is not the the magnetron?
If it's the Magnetron, it would sound like bacon cooking in the frying pan.
Ok, we gonna do some of your tests. Thank you so very much for your time and patience to answer my questions. I really appreciate it! God Bless You.
@@SpringfieldLARealtor If the HV cap inside your unit is alive and well, the voltages present in there will kill you instantly... I hope you're familiar with proper HV safety procedures / have a `chicken-stick` discharge resistor and know how to use the same. Handle it like an armed landmine until you're _sure_ it's been discharged.
hi ... Are there any way to repair the magnetron ??
Magnetron is a Valve / Tube, like in old-time radios (or more accurately, like small radar units). Once cooked, they're cooked :)
You sound like you know what you're doing.
It was difficult to see what you were doing at times with your connections.
With a new 9 volt battery mine measures 1.42.
Flip it around and the volt meter says zero.
I'm wondering if 1.42 going through it is high enough to start the micro heating or if that needs to be higher and the diode is shot.
At $5 to $20 dollars for a diode replacement it may be wise to start ripping open a few dead microwaves and saving some key components. New microwaves can be bought on sale for $30 to $50 dollars so it may not be worth it to sink $20 bucks into an old microwave.
Use 960 sumwa analog multimeter use 10k scale for checking microwave decide easily
First of all anyone working on a MW needs an amp meter in the power to see what its doing. We always used a megger to check the HV diodes, and for the other components unless you have an LCR meter to check the cap we used some used known good components off the shelf. A DVOM won't do you much good with the HV circuit. 3 to 5 amps is the filament current, then the Mag kicks in and the current ramps up to 15 or 20 amps. If you have a loud hum and all the HV components are ok its probably the tube.
it will either bet the HV transformer or the Magnetron. MrFixit
My LG Microwave stopped heating (internal bulb is not working either even after replacing the bulb).........would this be a faulty diode?
Stacy Webb No the diode has nothing to do with that side. check the ceramic fuse that says 10A inside the unit, and the plug top. A microwave will still show time/ clock , light and fan run, etc even with a faulty diode. make sure above all else that you unplug, leave for 10 mins and cross the terminals to ground with a sheathed screwdriver High risk of Death here !!! 3000 to 6000 and higher volts.
Paul Orbinson your capacitor can hold a charge so ground all terminals first and stay away from the magnetron , just looking for signs of fault can straight away show it is gone. burns or cracks or any smoke damage etc is a dead giveaway otherwise if it looks good it usually is.
It was the thermostat.........which was odd because all of the suggested diagnostics I came across on RUclips and other places, not one said anything about the t'stat.
Stacy Webb yeah I did that test before I got to the diode. just put the circuit tester across the stat, if it rings your good. I cant get a diode for my samsung ME 731K its Sept 14 model, I would never buy another thats for sure.
So what do you do if you've only got one multimeter ????
+Ivan Short connect a 9V battery and a 1k-ohm resistor to the HV Diode, the resistor will act as the test load. Connect +9V to the Anode, the Cathode to the resistor, then resistor to -9V. Measure the battery voltage. Now measure the voltage across the resistor. You should see about a 6V drop in voltage. Now if you reversed the Diode so it conducts in the opposite direction, you should get 0V across the resistor.. -MrFixit
Just try to obtain a replacement part. Good luck, you'll need it.
microwave diodes on amazon, 6 for $5.
9 volt dc is rather too low for testing a diode which is supposed to handle 5,000 volts. I would use at least a 2,000 volt source. The test demonstrated is appropriate for diodes used in 12 vdc circuits, not 5,000 volt circuits.
+Odouls77 Completely correct, sir. Also, I would like to point out that the Vf (forward voltage drop) is proportional to the current and voltage passing through the junction, and is affected by the PN junction temperature. V = (kT/e) Ln(I/I naught) Where as: I = forward output current e =electron charge k = Boltzmann's constant T = temperature in kelvin V = forward voltage
So as you can see, the drop Vf may be correct at 9.6 volts, but at 450 or some other arbitrary value, the drop may in fact be completely out of specification. Remember, always refer to the manufacturers data sheet for the proper IVT curves!
Would of been nice to see a schematic first.
My diode passes the test. But when it's connected the fuse blows. Any suggestions?
+Jake Jones Check your door switches, you may have a bad switch. -MrFixit
+ESRepair All my switches/connections test good. Two normally open and one normally closed. The microwave draws 55 amps thus blowing the fuse. When I disconnect (only) the diode from the frame, it draws about 5 amps. When I disconnect only the magnetron (everything else connected) it draws 55 amps. When everything is connected EXCEPT the single wire that goes from the transformer to the capacitor OPPOSITE the side that the diode is connected, it draws 5 amps. When I disconnect everything except
the diode and the transformer wire to capacitor opposite the diode it draws 55 amps.
Summed up: if the transformer to capacitor wire opposite the diode is connected AND the diode is connected, it draws 55 amps no matter if any or all the other wires are connected. These readings are approximates only so that you can know when the problem is happening. Also, just to rule it out, I am using a new diode.
[note: I am a HVAC tech, so you can be certain of my diagnosis]
Jake Jones bad h.v transformer
Put some foil paper on it.
@@danitzaayala8988 Turns out it was the transformer. Whoda thunk. Anyway, I barely remember making this post. But for what it's worth, the microwave has been working like a champ ever since (YEARS). And it gets used several times a day. Best part about it, just push the door closed (no handle) and press a lever down to open. Plus, it has NO (annoying/useless) TURNTABLE! Ahhh, the good ole days....
BTW anyone know the exact fwd bias voltage of these diodes?
The Voltage Drop on HV microwave Diodes is usually 3V. -MrFixit