# 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:** 20\ **Page:** 1
**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, 5:06am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/1 "2004-10-10T05:06:27Z")
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? ---
**Author:** ![unclviny](https://avatars.discourse-cdn.com/v4/letter/u/e274bd/32.png) [@unclviny](https://boards.straightdope.com/u/unclviny)\ **Post date:** [October 10, 2004, 5:22am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/2 "2004-10-10T05:22:06Z")
I don’t have any practical advice for you, would you like a lame-o joke instead? Why do they call it a “flyback” Because when you touch it you flyback across the room. Seriously, be VERY careful with TV’s, those Capacadiditators and things hold some serious charges (don’t ask). Unclviny ---
**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, 5:30am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/3 "2004-10-10T05:30:31Z")
is there a safe way to discharge one for certain, short of throwing it in a lake? I don’t want to ruin the DVD player, I want it to be an aquarium that plays DVDs ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [October 10, 2004, 5:39am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/4 "2004-10-10T05:39:08Z")
Yeah, leave it unplugged for about a week. You’ll be fine. ---
**Author:** ![Ruby](https://avatars.discourse-cdn.com/v4/letter/r/13edae/32.png) [@Ruby](https://boards.straightdope.com/u/Ruby)\ **Post date:** [October 10, 2004, 5:39am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/5 "2004-10-10T05:39:16Z")
Am I just being whooshed? An aquarium…that plays DVD’s? 😕 ---
**Author:** ![AmbushBug](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ambushbug/32/4600_2.png) [@AmbushBug](https://boards.straightdope.com/u/AmbushBug)\ **Post date:** [October 10, 2004, 5:45am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/6 "2004-10-10T05:45:12Z")
I work with some people who install & remove CRTs (from slot machines) and they had a technique for discharging them. I’d suggest taking it to a TV repair shop and offering them $5 to discharge it for you. One of these coworkers of mine said (urban legend brewing here?) that not only can they hold a charge for a while, but there was one occurrence when a monitor unit that was discharged was put on a (metal) shelf for several months, and it built up a charge again over time, from transient & ambient static electricity. To the detriment of the technician who was sure that the (electron) gun wasn’t loaded 😃 ---
**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, 5:46am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/7 "2004-10-10T05:46:40Z")
it’ll be approximately 5 gallons, will be using a whisper 10 hanging over the side and an airstone for all the filtration needs lighting will be a single 20 watt power compact standard-socket 50/50 bulb I will seal off the bottom of the unit so that salt and other such doesn’t affect the DVD player thanks! ---
**Author:** ![aerodave](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@aerodave](https://boards.straightdope.com/u/aerodave)\ **Post date:** [October 10, 2004, 5:51am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/8 "2004-10-10T05:51:17Z")
Do flat panels even have the same problem as CRTs? I wouldn’t be surprised if you didn’t find any giany capacitors in a non-CRT screen. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [October 10, 2004, 5:55am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/9 "2004-10-10T05:55:26Z")
> [@audilover](#): > > Do flat panels even have the same problem as CRTs? I wouldn’t be surprised if you didn’t find any giany capacitors in a non-CRT screen. I think he means a flat tube type, rather than a flat panel type. That’s the way I read it, at least. ---
**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, 5:58am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/10 "2004-10-10T05:58:55Z")
it is a flat tube, yes a flat panel wouldn’t have enough room for fish ---
**Author:** ![aerodave](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@aerodave](https://boards.straightdope.com/u/aerodave)\ **Post date:** [October 10, 2004, 6:22am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/11 "2004-10-10T06:22:02Z")
How’s the tube supposed to work if it’s got fish in it? That electron beam can’t be good for them. You did say this thing would be playing DVDs, after all. ---
**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, 6:39am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/12 "2004-10-10T06:39:09Z")
you don’t need the tube to play DVDs, it has video/audio out jacks on it I will set the aquarium DVD player on a table near the living room’s TV, it will be used to play DVDs and output the picture onto the living room TV while also containing fish, live rock, and hopefully some LPS corals 🙂 ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [October 10, 2004, 6:44am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/13 "2004-10-10T06:44:08Z")
> [@AmbushBug](#): > > One of these coworkers of mine said (urban legend brewing here?) that not only can they hold a charge for a while, but there was one occurrence when a monitor unit that was discharged was put on a (metal) shelf for several months, and it built up a charge again over time, from transient & ambient static electricity. To the detriment of the technician who was sure that the (electron) gun wasn’t loaded 😃 I doubt it was from static electricity. When you discharge something like a large capacitor or inductor then let it sit for a while, it “recovers” some of the lost charge. It’s not defying physics or anything, and in fact the equations it follows are very similar to what happens with heat. If you take a really hot brick and cool it down to room temp by dumping cold water on it, if you let it sit for a while the temp will slowly creep back up a bit as heat stored on the inside of the brick works its way to the outside. The same sort of thing happens with electrical devices. Lots of technicians have been bit by devices that were “discharged.” It’s not a UL. A lot of devices these days have bleeder resistors in them, but the moment you start depending on bleeder resistors is when one fo the little buggers is going to fail open and not do its job. ---
**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, 6:45am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/14 "2004-10-10T06:45:06Z")
so…your answer is that it’s never safe? ☹ ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [October 10, 2004, 9:51am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/15 "2004-10-10T09:51:22Z")
- - - I will pray for your fish; too much heat is bad for them. - But anyway: what you do is you need physical access to the [big] power supply capacitor[s] _leads_, and then you need to short each of the capacitor leads to (another) electrical ground with a resistor in line with the shorting wire. Just leave the shorting wire clipped on for a minute or two, and do every lead. The resistor can be 30K to 50K or so, a 1/4-watt will do fine. * * * - And I’ve never ever ever ever heard that capacitors could significantly “recharge” themselves up, after being discharged. And I’ve never ever heard that inductors could store any charge. But that’s just me. -With transformers you can get _capacitance_ between different windings, but an inductor only has one winding, which is… one long piece of wire. By what mechanism does the charge manage to polarize at opposite ends of this wire on its own? ~ ---
**Author:** ![gregongie](https://avatars.discourse-cdn.com/v4/letter/g/919ad9/32.png) [@gregongie](https://boards.straightdope.com/u/gregongie)\ **Post date:** [October 10, 2004, 10:05am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/16 "2004-10-10T10:05:20Z")
From what I’ve read, keeping a 5 gallon marine aquarium is near to impossible, especially if you intend to keep corals. I’d advise against it, unless you’re a pro. ---
**Author:** ![levdrakon](https://avatars.discourse-cdn.com/v4/letter/l/49beb7/32.png) [@levdrakon](https://boards.straightdope.com/u/levdrakon)\ **Post date:** [October 10, 2004, 11:07am UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/17 "2004-10-10T11:07:52Z")
Wow. I hope you’re at least going to use a ground fault interrupter at that outlet, and include a drip loop in the power cord, in case of a leak. Aren’t salt water aquariums usually on the cool side? Are you sure you want your DVD player heating up the aquarium? And what **gregongie** said. Maybe you could start with a couple freshwater guppies? ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [October 10, 2004, 1:43pm UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/18 "2004-10-10T13:43:53Z")
I’d be more concerned about the inevitable dripping from aquarium cleaning / feeding / maintenance / etc. getting into the guts of the DVD. Spilled water always goes downhill and it likes to get into small crevices where it’ll take days to evaporate. I predict a long an ddifficult process to build the aquarium, followed by DVD death within a week or two. ---
**Author:** ![MC\_E](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@MC\_E](https://boards.straightdope.com/u/MC_E)\ **Post date:** [October 10, 2004, 2:02pm UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/19 "2004-10-10T14:02:10Z")
> [@DougC](#): > > - > - > - I will pray for your fish; too much heat is bad for them. > > - But anyway: what you do is you need physical access to the [big] power supply capacitor[s] _leads_, and then you need to short each of the capacitor leads to (another) electrical ground with a resistor in line with the shorting wire. Just leave the shorting wire clipped on for a minute or two, and do every lead. The resistor can be 30K to 50K or so, a 1/4-watt will do fine. > > * * * > > - And I’ve never ever ever ever heard that capacitors could significantly “recharge” themselves up, after being discharged. And I’ve never ever heard that inductors could store any charge. But that’s just me. -With transformers you can get _capacitance_ between different windings, but an inductor only has one winding, which is… one long piece of wire. By what mechanism does the charge manage to polarize at opposite ends of this wire on its own? > ~ I worked for a comapany that designed some really cool stuff that relied on high-voltage electrical discharge (20-30kV). We had the big capacitors that were about the size of a kitchen trash can. When we took a device apart, we had to hard-wire the leads of the capacitor together to prevent any charge from building up. We forgot one time and found a capacitor that sat unshorted for about two weeks. When we did short it (safely) we got a spark the would have definitely knocked you across the room, if not worse. The capacitor had definitely been shorted immediately before we took the system apart, so it built back up somehow. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [October 10, 2004, 2:13pm UTC](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446/20 "2004-10-10T14:13:47Z")
I’m not sure how CRTs are designed today, but when I was a kid we followed a simple procedure to discharge a TV’s high voltage: 1. Unplug TV and remove rear cover. 2. Grab a long skinny screwdriver and an insulated wire with an alligator clip on each end. 3. Clip one end of the wire to someplace on the metal chassis (i.e. “circuit common” or “ground”). 4. Clip the other end of the wire to the screwdriver’s metal shaft. (With the above arrangement, the screwdriver becomes a “grounding rod,” i.e. anything you touch inside the TV with the screwdriver will be shorted to circuit common.) 1. Look at the CRT. You will notice a thing that looks like a rubber suction cup attached to the glass. 2. While holding the insulated end of the screwdriver with one hand, carefully shove the pointy end of the screwdriver under the suction cup thingy. In other words, don’t touch or try to remove the suction cup; just shove the tip of the (grounded) screwdriver under the seal, between the cup and glass. Keep pushing the screwdriver until the tip makes contact with the electrode, which is located in the center of the suction cup. The HV will be discharged when the tip of the screwdriver makes contact with the electrode. Anyway, this is how you discharge a conventional CRT… [Next page](https://boards.straightdope.com/t/how-long-for-a-tv-to-discharge-before-i-can-gut-it/268446.md?page=2)