How to remove the bleeder resistor in microwave capacitors.

Picture of How to remove the bleeder resistor in microwave capacitors.
In this instructable, we will discuss how to remove the bleeder resistor from the medium sized metal can capacitors such as those found in microwaves. This will not work for all capacitors. Some have an internal resistance which cannot be removed. The Samsung units, like those pictured below, are known to contain a removable resistor.

Please note that this is extremely dangerous, not to mention messy. If the resistor isn't working in the first place, chances are that the capacitor will already be holding a potentially lethal charge. Removing them ensures that it will be capable of holding a lethal charge. ALWAYS short the terminals before working with a capacitor. This is about as dangerous as climbing telephone poles. I don't recommend that anyone try this. Enter at your own risk!
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Step 1: Gather Necessary Tools

Picture of Gather Necessary Tools
Here is what we will need for the task:

0.99 The capacitor(s) you're going to mutilate of course
1. Nibblers or some type of cutting tool (the ones I used were purchased at Radio Shack)
2. RTV Silicone sealant (automotive section)
3. A work surface, preferably outside, that you don't mind getting full of nasty smelling oil and
brake cleaner
4. Brake Cleaner (rubbing alcohol may be substituted, but it won't work nearly as well)
5. Side Cutters
6. Mineral Oil (optional in case too much of the original oil is spilled)

Step 2: Hack open the capacitor

Picture of Hack open the capacitor
The first step is to open the capacitor. Using the nibbler, cut all around the top of the can. Try to keep it upright to minimize the loss of oil. All that is needed is to cut down through the first layer of metal and move to the next spot. Strong hand muscles are definitely a requirement.

Step 3: Pop the Top

Picture of Pop the Top
Now once you have cut all the way around, the top should just pop right off. Grab the terminals and pull. If it doesn't come off, that means you need to do more nibbling.
kill-a-watt7 years ago
I don't want to be the safety nazi, but you brought up the possibility that the bleeding resister has already failed open, and the fact that the cap may already hold a charge. Shouldn't we short the terminals first, just in case?
Hopefully those attempting this will know that already, but I'll add it just in case.

What are you after in removing the internal resistor of a capacitor?

Anyway, my problem is a busted microwave oven capacitor of these specs:

AC 0.82µF ±4%b


from an old Whirlpool with mechanical knob controls microwave oven.

I am having a hell of a time finding a replacement.

Can it be repaired at all.

With the resistor in there, I would need a powerful transformer to charge the capacitor. With it removed, it can be charged by something much weaker, such as a flyback driver.

For your capacitor, if you are sure that is what the problem is, it doesn't have to be an exact replacement. Anything that is equal to the voltage and farad rating or greater will work. For instance a 2400V 1µF capacitor will work just fine. I think that is a much more common size.

Thanks for your kind attention.

If I may, you sure are adventurous, because now I know that the internal bleeder is to dissipate the charge inside, so that it is safe or safer for repair people to service the oven.

Your purpose is to be able charge the capacitor faster with the internal bleeder resistor removed?

Well, that is adventurous, and also perhaps you would rather also save money from not having to buy a quick charging capacitor?

I am not any electronic engineer or hobbyist, etc., but you are one study of a stubborn what I might call a re-cycler -- it takes all kinds, though.

Glad to meet you, and thanks for the conversation.

Yes. Cheap capacitors are what this is all about. That and being able to charge them with a lighter, smaller, safer power supply. Though the caps themselves are still very dangerous when charged.

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.

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.

I started reading about repairs of microwave ovens in the internet, and
came to the conclusion that most likely the power capacitor is the

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?

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

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

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.

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

e-Mail sent.

Kirk6 months ago

Maybe you could pot it.

guruji13 years ago
Hi Lightning stalker I have another capacitor AWI cp618 made in korea what about these? Do they have bleeders underneath like the samsung?
guruji13 years ago
Is there another way to destroy the bleeder maybe or what if one puts other resistors in parallel to lessen effect so that one don't have to do this whole job?.
Thanks for sharing.
The Lightning Stalker (author)  guruji13 years ago
If you drill a hole in just the right spot it might break the bleeder in half, but its location is different on each capacitor. If you have some identical capacitors, you could take the one apart and then do this with the rest when you have located the bleeder resistor. You however risk getting metal shavings inside where they could cause shorts and you have to be careful not to go too deep. Probably a sharp tool like an awl would be a better way to do it. Then make sure the hole is clean and put some silicone on there.
guruji13 years ago
I've did this today . When I openend mine I broke the two contacts and soldered them back. Although I've put glue and silicone around still I think same as Zak to solder around better.
HoldOnTight3 years ago
Yea, i too missed the point of WHY would someone want to remove an internal resistor? What would the end product be used for? I suggest adding the reason you are trying to accomplish your goal to the start of the 'ible. What is the "bigger problem" as KillAWatt asked???
Zak7 years ago
I would suggect using oil from a donor capacitor, not engine oil. I'd fear the additives in engine oil might have a bad effect. As for the silicone, wouldn't it be possile to solder the capacitor shut? Finally, some really old ovens use an external resistor. Those are obviously the easiest to remove :)
The Lightning Stalker (author)  Zak7 years ago
No, it is not possible to solder the capacitor shut for two reasons. First, heating the capacitor makes the oil come out all over and make it impossible to get a reliable solder joint, and second, the bottom part of the can is usually aluminum which is impossible for solder to stick to. As for your other question, this is mineral oil, not engine oil. It is likely superior to the oil that is already in the capacitor.
But when you look at a capacitor that hasn't been hacked, you see how the lid is bent around the bottom part. Can't you just pry it up, and then bend it back in place?
ReCreate6 years ago
what if some one got shocked by one of those capacitors fully charged?
The Lightning Stalker (author)  ReCreate6 years ago
Their whole body would jump and it could possibly stop their heart.
Fun Fun Fun
The Lightning Stalker (author)  goeon6 years ago
It's happened to me. My arms flailed and I couldn't breathe for a couple seconds. I got a gash on my hand when it hit something. Luckily my heart didn't stop that time.
your heart dident stop "that time" Your heart stoped before???:P
The Lightning Stalker (author)  goeon6 years ago
It may have, but not from electric shock.
fuzvulf6 years ago
If children's toys from china have lead in them then whenever you work with scavenging from electronics using precaution against chemicals and carcenogens is always a good idea. That said. Old external AC units are also a good source of fairly large caps. Making friends with the local trade school electronics professors is also a good Idea. I made a contribution to their electronics club and got invited to their fund raising auction. Picked up a couple of shunt wound DC motors, a freqency generator, and a box full of assorted rediculously sized capacitors for less than I spend a week on soda and candy bars. Automotive epoxy like JB Weld works well for closing the can back up. They actually are almost as useful as altoids tins when working with slightly larger projects. One of our instructors managed to pry a can open insert a potted circuit and reclose the can to simulate an intermittent failure condition during hands on lab. Nice instructable.
The Lightning Stalker (author)  fuzvulf6 years ago
Thank you. I might try something like that.
GreenDay7 years ago
I can't really see it from the pictures, but what is the voltage and ferrad capacity of the capacitor?
The Lightning Stalker (author)  GreenDay6 years ago
It's quite readable at the original size. Just click on the i in the top left corner of the picture. Then on the page that comes up, under the picture you'll see, "original file:" the dimensions in pixels, and file size. Click on the dimensions and it brings the picture up at original size.
triggernum56 years ago
Great instructable, but what you need is a video showing what could go wrong here.. Its a big step up from most electricity based instructables that your typical uneducated kid is going to try blind
As I said above. Enter at your own risk.
Yea, but all instructables seem to say that.. This one though that warning shouldn't be taken lightly if ppl don't know exactly where the dangers are prior to reading this.. Just stressing the point, I learned good stuff about some cap internals from your write-up..
kill-a-watt7 years ago
hey, what the heck are you doing with these things once you have removed that bleeder resister anyway?
Double that question... I'd like to know... let me guess, capacitors for a HF unit for a home-fabricated GTAW unit (aka, TIG)? but even then, you wouldn't need bleeders out... hmm...
btop generz7 years ago
I was thinking that too. Maybe a tesla coil? Seems logical...
The Lightning Stalker (author)  btop7 years ago
I suppose they could be although there are 3 reasons not to use them: they're a bit large, not quite enough voltage, and probably have a high inductance which is undesirable in a Tesla coil. A low quality unit could be possible though...
Looks highly dangerous, but still, good Instructable. But you should have more than just three or four pictures, one of them being repeated over and over again.
Yes, sorry about that. It's the only picture I have which shows the relevant parts. The pictures are from a few months ago when I was actually doing this.
Oh, hahaha. No problem, it's okay. I always make videos and never upload them onto YouTube a long time after they're made.