# How long for a TV to discharge before I can gut it? **URL:** \ **Category:** Factual Questions\ **Created:** [October 10, 2004, 5:06am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446 "2004-10-10T05:06:27Z")\ **Posts on this page:** 6\ **Page:** 2
**Author:** ![Dan\_Turk](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dan\_Turk](https://boards.straightdope.com/u/Dan_Turk)\ **Post date:** [October 10, 2004, 2:46pm UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/21 "2004-10-10T14:46:59Z")
I have a 2.5g marine tank with thriving corals, inverts, and a fish…a 5g tank does not scare me. Heat will not be an issue, many things can be taken care of with fans and peltier coolers 🙂 thanks for the advice, everyone ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [October 11, 2004, 12:24am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/22 "2004-10-11T00:24:44Z")
**Dan Turk** : [Here](http://repairfaq.ece.drexel.edu/sam/tvfaq.htm#tvsafdis) is a complete description of how to _safely_ discharge a TV set. Note that it specifically rules out certain things that have mentioned in this thread so far. If you do not have the experience, equipment and understanding to follow these directions _under no circumstances should you attempt it_. As for leaving it unplugged, try 6 months. I’ve seen big charges coming from sets that have been unplugged at least a month. ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [October 11, 2004, 12:56am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/23 "2004-10-11T00:56:27Z")
> [@DougC](#): > > - And I’ve never ever ever ever heard that capacitors could significantly “recharge” themselves up, after being discharged. > ~ One of the experiments that was performed in my basic electronics course was to attach a multimeter to an electrolytic capacitor and charge the capacitor with a DC power supply. After the capacitor was fully charged, the power supply was removed and the terminals on the capacitor were momentarily short-circuited, discharging the capacitor. As soon as the short was removed, you could see the measured voltage slowly rising on the multimeter. The instructor didn’t explain why it happened, he wanted to demonstrate that a capacitor can be a shock hazard even after it had been discharged if a bleeder resistor was not present or had failed open. ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [October 11, 2004, 9:38am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/24 "2004-10-11T09:38:08Z")
> [@](#): > > …After the capacitor was fully charged, the power supply was removed and the terminals on the capacitor were momentarily short-circuited, discharging the capacitor. As soon as the short was removed, you could see the measured voltage slowly rising on the multimeter… - **mks57** - - - Shorting with just a simple conductor (or a screwdriver) is the _wrong way to do it_. If you do that, the voltage really only “bounces” back and forth between the plates of the capacitor, because there’s really not much resistance in the shorting wire. And your screwdriver (if you used that for shorting purposes) can end up slightly welded across a couple steel contacts. That is why I said that you should use a _high-value resistor_ in the line you use for shorting, and leave the shorting line in place for a couple minutes. Just like those instructions that **ftg** linked to–they tell you to use a resistor in the shorting line, and to leave the resistant shorting line in place “for a few seconds”. ~ ---
**Author:** ![mks57](https://avatars.discourse-cdn.com/v4/letter/m/b9bd4f/32.png) [@mks57](https://boards.straightdope.com/u/mks57)\ **Post date:** [October 11, 2004, 10:00am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/25 "2004-10-11T10:00:14Z")
> [@DougC](#): > > - > - > - Shorting with just a simple conductor (or a screwdriver) is the _wrong way to do it_. If you do that, the voltage really only “bounces” back and forth between the plates of the capacitor, because there’s really not much resistance in the shorting wire. And your screwdriver (if you used that for shorting purposes) can end up slightly welded across a couple steel contacts. That is why I said that you should use a _high-value resistor_ in the line you use for shorting, and leave the shorting line in place for a couple minutes. Just like those instructions that **ftg** linked to–they tell you to use a resistor in the shorting line, and to leave the resistant shorting line in place “for a few seconds”. > ~ This was a classroom demonstration of a phenomenon and a hazard. It wasn’t supposed to be an example of an operational procedure. ---
**Author:** ![spingears](https://avatars.discourse-cdn.com/v4/letter/s/ebca7d/32.png) [@spingears](https://boards.straightdope.com/u/spingears)\ **Post date:** [December 16, 2004, 3:25pm UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/26 "2004-12-16T15:25:47Z")
> [@Dan Turk](#): > > 20" flat screen that I want to gut and turn into an aquarium that plays DVDs. > How long should I leave it unplugged so I can be sure it’d be safe to operate on? This is a CRT? Don’t take chances. Discharge the CRT first with a grounded wire. The phosphors on the inner face of the tube may prohibit the use as an aquarium as fish are senstitive to any toxic chemicals. [Previous page](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446.md?page=1)