Instructables

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!
 
Remove these adsRemove these ads by Signing Up

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

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

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.

Step 4: Remove the Bleeder

If your capacitor is equipped with a standard bleeder resistor, you will find it making a connection between the two terminals just under the "cap". On these it was under the paper flap as in the picture below. These Samsung types use a special high voltage thin ceramic resistor. Either bend it back and forth until the metal fatigues, or cut it out with the side cutters. You can throw them away, but I save them for interesting things.

Step 5: Slop the Slop

Now that the bleeder is removed, add some mineral oil if the oil level fell below the top of the paper down inside. Put the "cap" back on and spray the brake cleaner all over the outside to remove all traces of oil. The RTV won't stick properly if there is any trace of oil on the outside. I alternate between spraying and wiping with Kleenex.

Once it's clean and dry, slop the RTV around the seam to seal things back up. It should look like the picture below. Put it somewhere out of the sun and where it won't be getting hotter to dry. If the temperature of the capacitor increases now, it will force the oil out of the seam and make a channel through the RTV and leak. You might need to brake clean and RTV several times like I did to eliminate all the oil leaks. All done! Enjoy your new extremely dangerous capacitor toy thing. When not in use, you would be wise to keep the terminals shorted with alligator clips or a jumper wire with disconnects on the ends like I have below.
kill-a-watt6 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.
Kirk21 hours ago

Maybe you could pot it.

guruji12 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?
Thanks
guruji12 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)  guruji12 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.
guruji12 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.
Thanks
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???
Zak6 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)  Zak6 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?
ReCreate5 years ago
what if some one got shocked by one of those capacitors fully charged?
The Lightning Stalker (author)  ReCreate5 years ago
Their whole body would jump and it could possibly stop their heart.
Fun Fun Fun
The Lightning Stalker (author)  goeon5 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)  goeon5 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)  fuzvulf5 years ago
Thank you. I might try something like that.
GreenDay6 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)  GreenDay5 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-watt6 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 generz6 years ago
I was thinking that too. Maybe a tesla coil? Seems logical...
The Lightning Stalker (author)  btop6 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.