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Thread: Hazards of capacitors

  
  1. #1
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    Hazards of capacitors

    Quote Originally Posted by gapajeff View Post
    .....Anyways today I found an old vacuum, 2 compressors and an old well pump. Also driving home found a microwave, and 2 really old TV's. Which I plan on tearing apart for the transformers.....
    (Bold added)

    From Wikipedia (The article is heavy on the math and science involved, but the important part is at the very end):

    Hazards and safety



    Capacitors may retain a charge long after power is removed from a circuit; this charge can cause dangerous or even potentially fatal shocks or damage connected equipment. For example, even a seemingly innocuous device such as a disposable camera flash unit powered by a 1.5 volt AA battery contains a capacitor which may be charged to over 300 volts. This is easily capable of delivering a shock. Service procedures for electronic devices usually include instructions to discharge large or high-voltage capacitors. Capacitors may also have built-in discharge resistors to dissipate stored energy to a safe level within a few seconds after power is removed. High-voltage capacitors are stored with the terminals shorted, as protection from potentially dangerous voltages due to dielectric absorption.

    Some old, large oil-filled capacitors contain polychlorinated biphenyls (PCBs). It is known that waste PCBs can leak into groundwater under landfills. Capacitors containing PCB were labelled as containing "Askarel" and several other trade names. PCB-filled capacitors are found in very old (pre 1975) fluorescent lamp ballasts, and other applications.
    I remember hearing a story, back when I was a kid (and really old TVs were brand new TVs), of somebody who was killed messing around inside a TV. At the time, I thought that must be BS, cause everybody knows things are safe once you unplug them. Sometime later, I learned about capacitors, and that it's really possible to get shocked by an unplugged eletrical device.

    I'm certainly not enough of an electrician or appliance person to know anything more specific, but it seems worth mentioning...

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    I'm not an electrician but this can happen. I know with old A/C units, you can get electrocuted by a capacitor after its been off a while. I don't know what capacitors look like in a TV, but I'm going to have to really check when I tear them apart. With A/C units and outdoor units, they are very easy to handle as long as you don't touch the upper part of it.

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    It's my understanding from watching a few youtube videos that you can take an insulated tool and short it across the terminals to discharge.

    Are capacitors recyclable/worth recycling?

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    Yea usually I either just cut the wire with insulated side cutters, or I'll take my channel locks and grab a piece of copper to go over the 2 terminals. I'd also like to know if they are worth recycling. I've been just throwing them on the "scrap" pile

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    there is a "suction cup" looking thing on the tube... If you take a screw driver and pop that out with a screw driver, you are effectively shorting it, and you should be fine from that point on. I have taken apart at least 100 of those things, and for most of them, I don't even do it. Its nothing to worry about unless you are pulling apart a crt that has been just been on.

    Most capacitors should just go in the shred pile. I think most of them are aluminum, but they are filled with oil, called a "dielectric", and that oil makes up most of their weight. If you want, you can try selling the big ones (like what I talk about below) on Ebay, but that market is already flooded with them.

    If have ever taken apart a microwave, there is also a BIG capacitor in there (as well as a BIG transformer). There is just as much of a possibility of electrocuting yourself from scrapping out a microwave as there is when scrapping out a CRT. attached is a picture of the capacitor from a microwave:
    Last edited by TheMetalizer; 12-03-2010 at 11:15 PM.

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    Which is the reason why when I see tvs I only am concerned about snipping the power cord. And for Microwaves I just scrap the entire thing as my local yard will take it as number 2.

    Im just starting out and dont have the room yet but in a couple of weeks I will have a shed and will start sorting more.

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    Ahh...but there's copper in them there microwaves. Last one I tore down had 2 lbs.

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    My father-in-law is a master electrician, and we got to talking about these one night. He said if you hit the power button on/off 2-3 times, it releases any electrical charge leftover.

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    Cool

    If your unsure, just take an insulated pliers or screwdriver and short out the cap's. In rare instances they have been known to recharge themselves somehow, long after being unplugged. Can cap's are small soup-can looking things inside tv's. They can range in size from 1/4" diameter up to 2"diameter. There is usually a - mark on them to designate the negative side.

    Here is a pic. of a line of Electrolytic capacitors.
    Last edited by Mechanic688; 07-21-2011 at 09:21 AM.

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    Agree with posters i deal with capacitors all the time. I am a journey man hvac installer. New capacitors will not discharge like the old ones. Just dont take them apart there is no need any way. The old capacitors can be discharged just by arching the two posts if you have a dual capacitor. Make sure you go from c to both of the other posts. Other wise one will still be charged. Likewise the only way to shock yourself with one is to ground both posts. And yes your skin will ground it. lol Be careful scrappers and thanks for the info on the microwaves ive been turning them down.

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    Quote Originally Posted by TheIrrationalist View Post
    there is a "suction cup" looking thing on the tube... If you take a screw driver and pop that out with a screw driver, you are effectively shorting it, and you should be fine from that point on. I have taken apart at least 100 of those things, and for most of them, I don't even do it. Its nothing to worry about unless you are pulling apart a crt that has been just been on.

    Most capacitors should just go in the shred pile. I think most of them are aluminum, but they are filled with oil, called a "dielectric", and that oil makes up most of their weight. If you want, you can try selling the big ones (like what I talk about below) on Ebay, but that market is already flooded with them.

    If have ever taken apart a microwave, there is also a BIG capacitor in there (as well as a BIG transformer). There is just as much of a possibility of electrocuting yourself from scrapping out a microwave as there is when scrapping out a CRT. attached is a picture of the capacitor from a microwave:
    I'm glad I found this thread, I just yesterday tried to cut open my first capacitor so I could recycle the aluminum and FREAKED out when fluid started leaking out - I had no idea what it was, I thought it was bad stuff!!

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    It's just a hi voltage oil kind of like a mineral oil.
    thanks for the info on the microwaves ive been turning them down.
    I'd walk across the street for them and carry them on my back if I had to. Really nice big transformers in them, definitely worth tearing into.

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    I love microwaves. So easy to take apart and so much copper !! Not as easy as box fans and ceiling fans which are my favs, but pretty easy...can't see just getting .o95 for them !! Not me !!! I might even walk down the street a ways M688.

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    I have a feeling the microwave caps have a chemical similar to mosqito repellant, thats just a guess by the smell & some writing on the case. Googled & found nothing.

    Diaryl ethan or something like that is printed on the caps.
    Last edited by eesakiwi; 09-24-2011 at 11:01 PM.


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