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I am planning a movie set which will contain old circuit boards from TVs, VCR's and other old electronics. The plan is to go to several Goodwill stores and buy up all of the TV's and such that they have, open them up and integrate them into the set. There is an electrical danger here due to charges still present on large capacitors. What is the best way to quickly and effectively remove these charges? Dunking these devices in a salt water bath seems like a good idea (we do not need for these devices to work.) If so, are there things we need to be aware of? If not, is there a better recommendation?

We will be getting around 60 items, so finding and discharging all of the capacitors individually could be a big problem.

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    \$\begingroup\$ I think storing them for a day in a mildly humid atmosphere will be more than enough. \$\endgroup\$ – Wouter van Ooijen Oct 15 '15 at 21:06
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    \$\begingroup\$ CRT TV's can retain charge for longer than that. More like a week after last use. \$\endgroup\$ – Fizz Oct 15 '15 at 21:23
  • \$\begingroup\$ youtube.com/watch?v=B3bRy1FO_fA or youtube.com/watch?v=UsL-rAUKswQ shows the usual procedure for CRT when you still care about it working. Alas I don't know what is the typical procedure is for disposal/recycling. \$\endgroup\$ – Fizz Oct 15 '15 at 21:34
  • \$\begingroup\$ I'd be more worried about the lead (Pb). \$\endgroup\$ – Andy aka Oct 15 '15 at 22:22
  • \$\begingroup\$ that is a bit scary. Unfortunately, I may not be working with the most tech proficient people on earth :/ \$\endgroup\$ – Hoytman Oct 15 '15 at 22:34
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I feel that giving all of the items a salt water bath is probably the best option for your circumstances.

However. Do not dispose of the water carelessly afterwards. There may be traces of lead and other nasties in it. Find some sort of hazardous waste disposal company and get them to get rid of it (it may cost you a few $$ but it will be quick and fairly safe if you are careful, rubber boots might be a good idea). Also, I have no idea how well sealed up everything is inside them but some of the capacitors might not be shorted by the water properly, if you don't go digging through things that look like they may act as a sealant and you make sure you get all of the air pockets out when you give them a bath I think you should be OK however.

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They sell "wands" to do this sort of thing (Google for "electric discharge wand") but you can make your own. It's just a wire with a clip on one end that you can touch to one end of the capacitor. The wire goes through a resistor to a clip on the other end for hooking up to the other side of the capacitor.

The trick is to find the right resistor value and size but that can be calculated judging by the size of the capacitor and how quickly you want them to discharge.

Of course, you don't want to be handling that with your bare fingers so ...

And with that last line, I have to stop cause it's been far too long since I've done that.

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  • \$\begingroup\$ Yeah, but this too time consuming for what he wants. He doesn't need them working. \$\endgroup\$ – Fizz Oct 15 '15 at 22:31
  • \$\begingroup\$ @RespawnedFluff There is no quicker way to do it except a dangerous short. This is the only safe way to do that. \$\endgroup\$ – Rob Oct 15 '15 at 23:07
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I'm going to say that it is ok to dunk each component in a salt water bath. It salt water will short out all of the caps and neutralize any lost over charges. This is fast and generally effective against and charged component that a person may accidentally touch later.

This method is fast and effective for items that you don't want to function anymore.

Be sure to wear gloves and don't come in contact with the water at any point during the activity.

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  • \$\begingroup\$ Lots of luck with the "don't come into contact with the water" bit. I predict a mess, greatly enhancing your probablity of getting a shock if anything is charged up. \$\endgroup\$ – Ecnerwal Nov 9 '15 at 0:52
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    \$\begingroup\$ Chances of you getting a shock due to charged capacitors in salt water is very low, unless you take your fingers close to (in between) the leads of charged cap. This video explains why. \$\endgroup\$ – Whiskeyjack Nov 16 '15 at 11:41

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