Ahhh brough back fond memories that did, I got some of my coolest hair styles from not discharging anode caps properly when i was younger...back then some teenagers got high on smoking and drinking...others like me got high on leaded solder fumes and anode cap shocks 😂
Back in the 60s, I was a sophomore in high school, I helped my uncle repair tvs and radios and they all had tubes. We did the right thing when discharging non-working CRTs and used a resistor to the positive and negative part of the CRT. We set the discharged CRTs on the floor waiting to take them to the dump. We labeled them discharged and when I grabbed one days later I found out they recharge themselves and I now have that experience burned into my memory. By the way, I am now a retired Electrician and never forgot about how static electricity gets into everything! I was trained in micro miniature repair and was very thankful to live though that experience at a young age.
Yesterday I found out capacitors recharge themselves even if you supposedly completely discharge them (can't remember the video on that), so as a CRT is basically a capacitor, it seems, then it will recharge itself too. Cool to know, I didn't think on that. Ok, then I stopped liking the idea of discharging it and feeling safe if it will charge up a bit again 😄.
@chu Harry What do you mean? Charge a capacitor up to full capacity, then short-circuit its terminals and remove the short and measure the voltage - you'll see it rise again (Not to its maximum, of course - at least from what we currently know of our Universe xD). The charges don't get back through the terminals - it's from inside. I don't remember the reason though. To oppose the change? (As Nature likes) No idea.
I spent almost thirty years putting off putting my hands inside a CRT chassis. This video was finally the one that gave me the confidence to understand exactly what to do-and exactly why. Also didn’t die, thanks!
remember boys and girls when discharging a crt always make sure to wait 30 mins and then discharge once more and thank you to retro recipes for making such an easy to follow guide to discharging crts
Not quite correct. Normally you should do it through resistor to avoid sparks and big current which can damage sensitive parts. The other thing is grounding your self. Not everything was said right. Those wrist grounding belts normally have 1M ohm(million ohm) resistor between your body and ground. If something is wrong with ground wiring in your installation, then your fridge is one million times (about) more dangerous than grounding wrist belt (if made correctly).
@mophus Actually the resistance from that top corner ground lug to the logic board is quite good, and there's virtually no chance of damage to the board. however back in the day some people would connect to the chassis instead of the ground lug that I showed, and the distance between that and the logic board is less because it is nearer. As a result Apple released a discharge tool with a resistor built-in because people were connecting to the wrong ground point and damaging the board as you say. If you connect where I connected I've never heard of this causing damage. As for the wrist strap, I cannot and would not want to state in my video that every wrist strap on the Internet is safe. The point is that you do not need to ground yourself at all. That was really what I was aiming to demonstrate. There is no need for a ground of any kind. Therefore wrist straps are a moot point. Cheers.
@@mophus6461 I used a resistor in my self-made discharging tool at first as well, then I had an interesting conversation with a professional tv repair guy who advised to leave the resistor out. The benefit is that you have visual and audible feedback when discharging properly. Easy way to be sure it worked. I found that quite convincing. I had the same worries about damaging components but he said that if you use a ground close to the screen (like the lug), he never experienced anything bad happening to other components.
Memory munchers, I hope you like this simplified layperson explanation. Please remember it's not not intended for electronics engineers nor to go into a lot of detail, it's just an analog-TV analogy! Thanks to Jan, David, & Stanford's Tom Lee. Oh & needless to say, watch the whooole video before commenting about the video below, and cheerio! 👍🕹️ Your friend in retro, Perifractic
I'm sorry but i am still pretty sure that this is not the complete explanation and there are still some dangers present. When the monitor is connected to ground, the negative terminal of the capacitor is referenced to ground and for the sake of argument, let's say that the positive terminal is offset 200 volts from the ground referenced negative terminal. If you short the capacitor while the negative terminal is ground referenced, both terminals will be referenced to ground. HOWEVER, when the reference to ground is removed, the voltage will equalize between the two terminals, ending up at 100 volts with reference to ground. You still see a spark and the potential is halved but this can still do some damage.
I'm not a professional either and i may be wrong but i have spent countless hours studying electronics and safety should come first. The only way i can see which would make this safe is if the negative terminal of the capacitor is actually biased to negative 100 volts and the positive to positive 100 volts so that they equalize towards 0. But this is a big if, depending on the design of the monitor.
Question regarding the decharing tool: Do you need any kind of specific cable type for the grounding (the one with the crocodile clamp you connect between the screwdriver and the ground lock)?
Side note: Discharge large capacitors and CRTs using the one hand behind your back method. Once you've connected up your discharge croc clip lead, place the other hand behind your back and leave it there while you're trying to complete the discharge. In the event you do manage to shock yourself, it reduces the risk that the shock will travel from arm to arm to ground, and thus across your heart.
Very true. I do mention this in one of the popup titles, but there's a lot of info there. Another good way is to stick your hand in your pocket like Alanis, thus reducing the instinct to bring it out to give yourself a... hand. 👍🕹
Yep. This is actually a method that I was taught. In certain situations, the hand behind your back reminds you not to make your body the thing that completes the circuit.
I'd be wearing hand gear that has high electrical resistance. Of course, you can still be shocked wearing rubber gloves; electrical resistance is never, not ever 100%. It's impossible. Also, don't stand on carpet or anything that is electrically conducive in any capacity. Static cling is electricity, after all...
just don't touch the tube with both hands, anyway I got shocked by the CRT one time time it's a pretty good jolt but not enough to really hurt you. I've also seen techs get shocked by the high voltage, 25,000 volts and they were not hurt. but never play around with it.
It is important to know that capacitors, especially CRT's can rebuild a charge even after being discharged. It is safest to be aware of this phenomenon and understand how to mitigate it (maybe keep the capacitor shorted out while working on it with power disconnected).
Even though I can never see myself ever having to discharge a CRT I still find your vids bloody entertaining sir! and now everyone knows how to do it correctly ;)
I really appreciate that you went out of your way to make sure this had correct information in it, while also being respectful of the confusion--I remember you asked a week or so ago in a social media group we're both in if the TH-cam comments had a point at all, and everyone was appalled! How could someone possibly think leaving the mains connected was okay?! But regardless, you presented the info accurately and respectfully enough here, and we're thankful you took the time.
I'm trying to restore my parent's old RCA from the late 80s/early 90s and been researching about discharging CRTs for the past month. Needless to say, this video really helped me out after being confused after reading various comments. The only thing I'm dreading is cleaning up all the dust/tobacco/possible pathogens that's accumulated over nearly 3 decades. It isn't pretty and will probably require me to clean thoroughly with a toothbrush lol Thanks for this video, you made it at the perfect time for me :D
So this video, the 8 bit guy, and a couple others made me immediately buy an empty classic case that already had the screen removed. I’m not dying for my retro computer DIY project. Thanks for saving my life!
Nice Video ...It all went a bit Electroboom for a second LOL ....Well I am an electrical engineer.....no ..really...I am ..you're method of discharging is spot on .... It should also be noted that a lot of older CRT's have so called 'live chassis' .. which just means they have a non isolated Power supply on the main PCB ...which in turn means large parts of the main PCB and often the chassis its screwed to is referenced to the mains supply ....On CRT's like that the metal Chassis is not designed to be connected to ground at all...another reason not to go poking around in CRT's unless you have unplugged them and waited a while ....stay safe people please.
I think people don't realize that you're discharging the HT capacitors by shorting them to themselves and as the negative side of those capacitors is connected to chassis ground - the way you're doing it will work. however the real correct way is to use a load resistor across the capacitor terminals to avoid damaging sensitive components on your board but even so that's rare and frankly I just do the "make a big spark" version
Correct. In fact Apple's own repair docs used to say to connect to the exact ground lug on the corner of the screen that I used. That is because there's more resistance between that and the logic board then there is between the chassis and the logic board. It's simply further away. You are correct if you connect to the chassis there may be a small chance of damage. That's why Apple released a discharge tool which was basically a screwdriver with a resistor built-in, as you say. 👍🕹️
I see so many backseat/armchair amateur electronics experts in retro repair vid comment sections with ignorant or seemingly totally made up information that it just became a silly prospect to try to correct them all.
My hand was sucked by the electronics and my body was stiff until the energy went through me. Then I fell to the ground. Unfortunately, I did not have superpowers after that, but luckily I remained the idiot I've always been.
RetroRGB sent me here. Great video! This makes so much more sense to me now than any other way it's been explained. I'm not that into electronics, just curious really. But now if someone holds a gun to my head to make me discharge a CRT, I know how to do it right (and why)! Now off to check out your other videos...
As someone in the process of restoring a Sony 20M4E and recently gone through the stressful disharge process, it's mad to see the plainly incorrect and dangerous comments from some people! I left it powered off for a week, cable disconnected and occasionally would press the power button to drain any charge left. Used a long insulated screwdriver, with good quality crocodile clips connected to the end of the tool and a ground point on the chassis. Also a pair of (expensive!!) insulated gloves and decent goggles. These things have bleed resistors but you can't be too safe. Even said goodbye to the dogs beforehand!!
Have you ever touched the side of a light switch when it is on? I have; nothing happens because the electric current is not being interrupted. It's when the switch is off that you can feel electric current. Yes, that is dangerous but on the switches I've done this experiment with (keep in mind that there are thousands of different switches and voltages as well as resistances), a small area will have enough voltage to induce vibrating sensations, akin to how a PlayStation DualShock controller feels when it vibrates lightly. It's kinda weird, and after some time, it will numb the area touching it, so don't hold your finger on that part for too long, and don't touch the area when turning the switch on or off. Again, this is an experiment to attempt but with extreme caution. Electricity is not a toy, kiddos (unless you're Nikola Tesla). Also, I cringed when I saw Björk touch the metal of the tube...of course, since the TV was already ready to disassemble, I imagine that the CRT was discharged in advance, long in advance. Hell, maybe the TV is just a prop, I dunno, lol That silly bit where you touched the anode and got 'zapped', ya got me with the unexpected loud volume; if you really had been zapped, we wouldn't of seen anything other than you retracting your finger (as well as spewing out a vulgarity slew lolz) and probably sucking on a fresh wound. I got zapped by my LCD monitor a few years back because I didn't have a grounded power cable for it and I touched the metal part of the display connector when trying to find it from behind. Left about an eighth-inch deep incision in my index finger, that did. Hurt for a damn week, to boot, akin to that of a deep wood splinter. I'd rather feel the vibrations of a powered-off light switch plate than ever deal with ungrounded electronics again, lolz
Nice video Peri Sim...Chris Fra...err friend. I was about to post on your your May 11 video but then I searched the internet just to make sure I wasn't off my rocker and found no evidence that you needed to plug it in. So nice to finally see the explanation of why. I've discharged a few in my younger days and did have the plug in the wall with power turned off and then immediately unplugged it as I got to work. But yes, that does seem kind of dumb now that I think of it since if there was a problem with the on/off switch...zap. At least I was safe enough to not touch it with my bare hands and only had one hand on the unit. I swear back in the early 90's I had a Mac repair kit that came with a wrist strap ground that plugged into the power cord (i.e. it had just the one ground wire poking out).
I've actually started discharging my CRTs via a high voltage meter after once suggesting on Reddit that someone plug in the AC cord for grounding prior to a screwdriver discharge and being swiftly corrected. Logic being that a high voltage probe acts as a several mega-ohm resistor to the chassis, and provides a slow, no-spark discharge that you can watch via the needle on the meter. For some reason my logic prior to this was, "I want to be grounded, and I want the CRT chassis to be grounded so that we are at the same potential during the discharge" when in reality, if I had taken a second to think it through, I would have realized that I'd be at the same potential as the CRT chassis as soon as I'd touched it anyway, making a discharge without anything being connected to earth perfectly safe (and in fact, if I am *not* grounded, that eliminates a path through my body by which the discharge could happen anyway). Just one of those weird gaps in my thought process (and I studied electronics in college) that I needed some extra help to fill in.
I´m forced to admit, even though I was following along your detailed explanation, I literally jumped backwards in horror when that spark happened. You got me good. I actually thought you shocked yourself for a second!!! Damn you!! :D :P Anyway, thanks for making this video and for pointing us to a useful piece of literature on the subject matter.
Hahaha, damn you got me there, I lumped. hahaha. This was such a good EP man. Fantastic. That smooth silky 12 cylinder engine you call a brain is really running at the top of its game. keep it coming.
Thanks for keeping a lid on the panic. CRTs are absolutely dangerous, and should be handled with care, but they aren't going to kill you if you don't make yourself part of the circuit.
they aren't going to kill you, I've been doing this since 1965 when I took classes in high school. problem is when you get shocked you jump away from it, I probably would have dropped a CRT but I was wise enough to have my dad help me load it into the car that day. I got a pretty good jolt but it won't kill you.
For all the people who think that both Chris and David or Jan Beta or many other people who are dedicated to this; they are wrong ... maybe u are wrong, because the physical Earth is not the same as the ground! As explained in the video, is a CRT a large capacitor? Yes, but I prefer to call it a Leyden bottle. Of course, the Leyden Bottle is the primitive capacitor, so yes, it is a capacitor. And the CRT is connected to the ground of the device, not to the physical earth. All switching mode power supplies are separated into two sections, the hot area and the cold area. The hot area is where they come from (without isolating, of course) the live, the neutral and the physical EARTH of your outlet. But the cold zone is isolated (in most of the time, in the old televisions there is a hot chassis and no, they are not isolated), but in modern Power supplys are isolated and there is a positive voltage, GND or 0V and, sometimes, a negative tension. So GND Ground It is not the same as Earth. 0V is not necessarily the absolute zero but it is a return path for the circuit to close. These grounds are also called floating earths since what they do is to be floating a little above the voltage they should be at, 0 Volts . If you look in any psu, a most of the times a blue 1kv Y1 disk ceramic capacitor is located between Earth and Earth for high frequency voltages or transient parasitic voltages. If you connect the Earth with the ground, something may explode or blew up
Huh, peeps talking about what they don’t know, that’s never happened before. I was a trained electronics repair tech at one time and this is a tried, true, classic, sensible, informed, scientifical, and safe way.
When discharging caps I usually use a big resistor to go easy on a cap itself again it is a drastic way of doing that, 100 % effective tho I'll admit. To be honest I never was 100% sure where the charge goes if you short tube as you've shown, so I've always directed it to ground prong on power outlet....
@@RetroRecipes absolutely no need whatsoever.. it really made me laugh.. thank you.. yes, Git is still widely said in the north of the UK or is it said widely?
And always discharge it to the CRT itself directly (the frame around the bell or the black conductive paint), and not the circuit chassis/ PCB ground, as some CRT monitors/televisions may have circuits that measure the beam current connected between the CRT bell and the main ground, and you might damage that.
I have an old rubber handle screw driver I soldered a wire to then heat shrink wrapped it up to the end leaving about 1cm then put a mains plug on the other end wired into the earth,in the UK we have 3 pin plugs I took the live and natural pins out just leaving the earth, I just plug it into the wall socket and discharge the CRT that way I leave it on for about 10 mins because they do have a habit of slightly recharging, I've had the odd small shock where I haven't kept it on long enough.
How can they 1) sponsor so many youtubers, 2) deliver stuff for near free? It is either a Chinese governement spying agency to collect electronics IP, or the TH-camrs are sponsored with almost nothing just like 5 free PCBs.
Awesome video! Another safe way to allegedly discharge the tube is to let it sit, unplugged, for 24hrs. It will slowly discharge naturally this way. I make no promises. An unsafe way is to discharge it with your tongue while grounded. Don't mention this method to Björk.
Tbh listening to bjork is super relaxing. About the discharge of CRTs, thank you for the info tbh, bc we all know how the internet works ad you can't be sure about nothing lol
As one of the people quoted in those responses, but NOT among those who suggested leaving it plugged in... Those kids suggesting to leave it plugged in are thinking of modern day ATX power supplies that have a toggle switch on the back. The switch disables the power leads but leaves ground/earth connected. But this doesn't apply to old PSU's like a classic Mac, or anything else without that switch. On the other hand... This whole video is based on a theory that shorting, with the heat and light from a small spark supposedly discharging an entire a lethal load, is better than sending it to earth. It usually works... in theory. You should be advising people to get their ground/earth wiring checked up to code by a licensed electrician, rather than merely insinuating their home is wired incorrectly.
I took my TV apart in the 90s and stuck my finger under that plug thing your sticking your screwdriver in on the tube and it gave me a right bloody good electric shock! Damn hurt, I thought I'm never gonna try and fix a TV again! Also once my dad had bodged cable extension onto our TV and sometimes cause it was loose the TV used to lose power so I tried to fiddle with the junction block one day whilst it was plugged in and got 240Volts through me...Pow, I flew across the living room!
Yes, CRTs are capacitors, indeed. But its not the electrons themselves that are converted to heat or light when you short a capacitor, it is the _potential energy of the charge_ (electric potential difference between poles). The electrons are simply rushing from the negative pole into the positive one, releasing energy. Also, not all capacitors have fixed polarity, as you implied early on, that's electrolytic capacitors only (including tantals etc).
Nice cracking vid! Happy what you unearthed your findings pointing the risks of beeing the referance ground! Other wise Robin would say holey smokes Batman!
Before watching this video I envisioned a mushroom cloud forming over the remnants of retro recipes headquarters... a good thing turned out far less drastic than imagined. :) Björk... she was touching.... oops....
I can still remember my old electronics teacher in High School Mr. LaSavio ( who wasn't allowed to call us idiots, so he called us Quiche eaters!) showing us how to work on CRT TV sets (yes this was a long time ago), of course me being the know it all was working around the fly back transformer with a large screwdriver. I then proceeded to short the cathode on the picture tube with said screwdriver, resulting in me being blinded and thrown backwards across the room! Then you heard across the room a very angry Mr. La Savio yelling "You Quiche Eater!" I looked pretty stupid on top of a crushed trash can ( yup, it was a metal one) holding a melted screwdriver!
The negative is the painted on, black coating on the outside of the back of the picture tube. It is called an aquadag coating and conducts electricity to the chassis!
Same thing with PSU. Pull the power cord when it's turned on. You will see that the energy is gone. But of course short it too if you can't wait for days. Measure before doing anything more.
Yes, I've learned something new :-) Every day's a school day! That ElectroBOOM moment though, gave me a jolt like I'd just touched the tube!! Thank's for potentially saving my life ;-) Oh and love Björk, she's as mad as a hatter and the world is a better place for her.
You got me on your fake spark! I jumped!
So you were The 8-Bit High? ...I'll get my coat.
I’m glad I’m not the only one. Although the crt didn’t stop any hearts that scene might have.
That fake spark was well done!
The 8 bit guy RULES!
Ahhh brough back fond memories that did, I got some of my coolest hair styles from not discharging anode caps properly when i was younger...back then some teenagers got high on smoking and drinking...others like me got high on leaded solder fumes and anode cap shocks 😂
Back in the 60s, I was a sophomore in high school, I helped my uncle repair tvs and radios and they all had tubes. We did the right thing when discharging non-working CRTs and used a resistor to the positive and negative part of the CRT. We set the discharged CRTs on the floor waiting to take them to the dump. We labeled them discharged and when I grabbed one days later I found out they recharge themselves and I now have that experience burned into my memory. By the way, I am now a retired Electrician and never forgot about how static electricity gets into everything! I was trained in micro miniature repair and was very thankful to live though that experience at a young age.
Yesterday I found out capacitors recharge themselves even if you supposedly completely discharge them (can't remember the video on that), so as a CRT is basically a capacitor, it seems, then it will recharge itself too. Cool to know, I didn't think on that. Ok, then I stopped liking the idea of discharging it and feeling safe if it will charge up a bit again 😄.
@chu Harry What do you mean? Charge a capacitor up to full capacity, then short-circuit its terminals and remove the short and measure the voltage - you'll see it rise again (Not to its maximum, of course - at least from what we currently know of our Universe xD). The charges don't get back through the terminals - it's from inside. I don't remember the reason though. To oppose the change? (As Nature likes) No idea.
@chu Harry Oh, ok, cool to know. Will see more about that when I can. Thanks!
@chu Harry aactuallllyyy
6:52, I nearly jumped out of my chair. :(
same
And not funny
me too!
same here jaja, it was a better scare than most modern horror movies.
yap me too. almost had a heart attack...
I spent almost thirty years putting off putting my hands inside a CRT chassis. This video was finally the one that gave me the confidence to understand exactly what to do-and exactly why. Also didn’t die, thanks!
Pure luck I guess ...lol
Im sure the ones that did die will be sure to come back here and let us know...oh, wait....
remember boys and girls when discharging a crt always make sure to wait 30 mins and then discharge once more and thank you to retro recipes for making such an easy to follow guide to discharging crts
This is the correct way to do it! Listen to what Björk says, she's a professional! (Yes, Peri you got it right, too...)
Cheers mate. It's true, I read it in a Danish book this morning.
So that's the correct way. But I like the Jan Beta way better: destroy the plastic case with a drill THEN discharge the screen ;)
Not quite correct. Normally you should do it
through resistor to avoid sparks and big current which can damage sensitive parts.
The other thing is grounding your self. Not everything was said right. Those wrist grounding belts normally have 1M ohm(million ohm) resistor between your body and ground. If something is wrong with ground wiring in your installation, then your fridge is one million times (about) more dangerous than grounding wrist belt (if made correctly).
@mophus Actually the resistance from that top corner ground lug to the logic board is quite good, and there's virtually no chance of damage to the board. however back in the day some people would connect to the chassis instead of the ground lug that I showed, and the distance between that and the logic board is less because it is nearer. As a result Apple released a discharge tool with a resistor built-in because people were connecting to the wrong ground point and damaging the board as you say. If you connect where I connected I've never heard of this causing damage. As for the wrist strap, I cannot and would not want to state in my video that every wrist strap on the Internet is safe. The point is that you do not need to ground yourself at all. That was really what I was aiming to demonstrate. There is no need for a ground of any kind. Therefore wrist straps are a moot point. Cheers.
@@mophus6461 I used a resistor in my self-made discharging tool at first as well, then I had an interesting conversation with a professional tv repair guy who advised to leave the resistor out. The benefit is that you have visual and audible feedback when discharging properly. Easy way to be sure it worked. I found that quite convincing. I had the same worries about damaging components but he said that if you use a ground close to the screen (like the lug), he never experienced anything bad happening to other components.
Bjork's dad is a prolific electrician and wrote books on the subject. No surprise she knows a bit about electricity.
Wow that’s amazing
"You shouldn't let poets lie to you."
Words to live by.
OK, I'm not ashamed to admit you actually scared the Hell out of me with that spark....lol. Doesn't help that I had the volume up too loud.
"Attach to scrotes for additional thrill seeking value"
👌🏾🤣🤣🤣🤣🤣🤣
Memory munchers, I hope you like this simplified layperson explanation. Please remember it's not not intended for electronics engineers nor to go into a lot of detail, it's just an analog-TV analogy! Thanks to Jan, David, & Stanford's Tom Lee. Oh & needless to say, watch the whooole video before commenting about the video below, and cheerio! 👍🕹️
Your friend in retro, Perifractic
I'm sorry but i am still pretty sure that this is not the complete explanation and there are still some dangers present.
When the monitor is connected to ground, the negative terminal of the capacitor is referenced to ground and for the sake of argument, let's say that the positive terminal is offset 200 volts from the ground referenced negative terminal.
If you short the capacitor while the negative terminal is ground referenced, both terminals will be referenced to ground.
HOWEVER, when the reference to ground is removed, the voltage will equalize between the two terminals, ending up at 100 volts with reference to ground.
You still see a spark and the potential is halved but this can still do some damage.
The safest solution would be to connect ONLY the ground-pin of the power connector to the ground-pin of an outlet.
I'm not a professional either and i may be wrong but i have spent countless hours studying electronics and safety should come first.
The only way i can see which would make this safe is if the negative terminal of the capacitor is actually biased to negative 100 volts and the positive to positive 100 volts so that they equalize towards 0.
But this is a big if, depending on the design of the monitor.
As stated in your video, APPLE-professionals supply their view on how to best discharge a MAC-CRT.
This is not necessarily true for all CRT's.
Question regarding the decharing tool: Do you need any kind of specific cable type for the grounding (the one with the crocodile clamp you connect between the screwdriver and the ground lock)?
Side note: Discharge large capacitors and CRTs using the one hand behind your back method. Once you've connected up your discharge croc clip lead, place the other hand behind your back and leave it there while you're trying to complete the discharge. In the event you do manage to shock yourself, it reduces the risk that the shock will travel from arm to arm to ground, and thus across your heart.
Very true. I do mention this in one of the popup titles, but there's a lot of info there. Another good way is to stick your hand in your pocket like Alanis, thus reducing the instinct to bring it out to give yourself a... hand. 👍🕹
@@RetroRecipes Ah, I must have missed it! :)
Yep. This is actually a method that I was taught. In certain situations, the hand behind your back reminds you not to make your body the thing that completes the circuit.
I'd be wearing hand gear that has high electrical resistance. Of course, you can still be shocked wearing rubber gloves; electrical resistance is never, not ever 100%. It's impossible. Also, don't stand on carpet or anything that is electrically conducive in any capacity. Static cling is electricity, after all...
just don't touch the tube with both hands, anyway I got shocked by the CRT one time time it's a pretty good jolt but not enough to really hurt you. I've also seen techs get shocked by the high voltage, 25,000 volts and they were not hurt. but never play around with it.
I had a glass of cold Coke in my hands as the sparks flew, and so did the Coke all over my chair and pants.
Lol OMG I am so sorry! 🙇
It is important to know that capacitors, especially CRT's can rebuild a charge even after being discharged. It is safest to be aware of this phenomenon and understand how to mitigate it (maybe keep the capacitor shorted out while working on it with power disconnected).
OMG I never seen a younger version of Bjork. She's so damned adorable.
Who is she anyway? Never seen or heard of her.
th-cam.com/video/htobTBlCvUU/w-d-xo.html
@@RetroRecipes Don't forget this classic, I love Björk th-cam.com/video/yvgVsxaqYgA/w-d-xo.html
@@RetroRecipes I never saw this one. Thanks!
looks like a boy, my dude
6:50 I got scared so badly I jumped in my bed 😆😆
Even though I can never see myself ever having to discharge a CRT I still find your vids bloody entertaining sir! and now everyone knows how to do it correctly ;)
Good explanation. I'm a jedi level CRT restorer and approve this message & Bjork of course.
I really appreciate that you went out of your way to make sure this had correct information in it, while also being respectful of the confusion--I remember you asked a week or so ago in a social media group we're both in if the TH-cam comments had a point at all, and everyone was appalled! How could someone possibly think leaving the mains connected was okay?!
But regardless, you presented the info accurately and respectfully enough here, and we're thankful you took the time.
I'm trying to restore my parent's old RCA from the late 80s/early 90s and been researching about discharging CRTs for the past month. Needless to say, this video really helped me out after being confused after reading various comments.
The only thing I'm dreading is cleaning up all the dust/tobacco/possible pathogens that's accumulated over nearly 3 decades. It isn't pretty and will probably require me to clean thoroughly with a toothbrush lol
Thanks for this video, you made it at the perfect time for me :D
So this video, the 8 bit guy, and a couple others made me immediately buy an empty classic case that already had the screen removed.
I’m not dying for my retro computer DIY project. Thanks for saving my life!
Nice Video ...It all went a bit Electroboom for a second LOL ....Well I am an electrical engineer.....no ..really...I am ..you're method of discharging is spot on .... It should also be noted that a lot of older CRT's have so called 'live chassis' .. which just means they have a non isolated Power supply on the main PCB ...which in turn means large parts of the main PCB and often the chassis its screwed to is referenced to the mains supply ....On CRT's like that the metal Chassis is not designed to be connected to ground at all...another reason not to go poking around in CRT's unless you have unplugged them and waited a while ....stay safe people please.
I was wincing while watching that clip and hoping Björk wouldn't end up getting zapped.
Same
I think people don't realize that you're discharging the HT capacitors by shorting them to themselves and as the negative side of those capacitors is connected to chassis ground - the way you're doing it will work. however the real correct way is to use a load resistor across the capacitor terminals to avoid damaging sensitive components on your board but even so that's rare and frankly I just do the "make a big spark" version
Correct. In fact Apple's own repair docs used to say to connect to the exact ground lug on the corner of the screen that I used. That is because there's more resistance between that and the logic board then there is between the chassis and the logic board. It's simply further away. You are correct if you connect to the chassis there may be a small chance of damage. That's why Apple released a discharge tool which was basically a screwdriver with a resistor built-in, as you say. 👍🕹️
@@RetroRecipes I built one of them when I was a young engineering student but it quickly fell out of use because it wasn't as fun
I find that if you do the "cord yank" method demonstrated, there isn't a big spark and it's less likely to damage anything.
I see so many backseat/armchair amateur electronics experts in retro repair vid comment sections with ignorant or seemingly totally made up information that it just became a silly prospect to try to correct them all.
Oh, I love Björk... so cute 😍
Bjork: I read that in a Danish book this morning. 😂
Your zap prank literally made me flinch lol
Me too. Funny how that works.
You honestly scared me with that edited bit there, good thing you know how to discharge CRTs in a secure way 😱
I love the way you gently silenced those self proclaimed engineers!
Aww, Bjork is so cute. "The Department of Redundancy Department" lol.
i have once discharged a CRT through my body. It was awesome.
Might I ask how it felt?
My hand was sucked by the electronics and my body was stiff until the energy went through me. Then I fell to the ground. Unfortunately, I did not have superpowers after that, but luckily I remained the idiot I've always been.
RetroRGB sent me here. Great video! This makes so much more sense to me now than any other way it's been explained. I'm not that into electronics, just curious really. But now if someone holds a gun to my head to make me discharge a CRT, I know how to do it right (and why)! Now off to check out your other videos...
I laughed at the comments you put at the start. UNPLUG IT!!! PULL OUT THE CORD!
Thanks for this one. I've always been confused as to where to ground my CRT's to and always been afraid of doing it wrong with the cable unplugged.
As someone in the process of restoring a Sony 20M4E and recently gone through the stressful disharge process, it's mad to see the plainly incorrect and dangerous comments from some people! I left it powered off for a week, cable disconnected and occasionally would press the power button to drain any charge left. Used a long insulated screwdriver, with good quality crocodile clips connected to the end of the tool and a ground point on the chassis. Also a pair of (expensive!!) insulated gloves and decent goggles. These things have bleed resistors but you can't be too safe. Even said goodbye to the dogs beforehand!!
Have you ever touched the side of a light switch when it is on?
I have; nothing happens because the electric current is not being interrupted. It's when the switch is off that you can feel electric current. Yes, that is dangerous but on the switches I've done this experiment with (keep in mind that there are thousands of different switches and voltages as well as resistances), a small area will have enough voltage to induce vibrating sensations, akin to how a PlayStation DualShock controller feels when it vibrates lightly. It's kinda weird, and after some time, it will numb the area touching it, so don't hold your finger on that part for too long, and don't touch the area when turning the switch on or off.
Again, this is an experiment to attempt but with extreme caution. Electricity is not a toy, kiddos (unless you're Nikola Tesla).
Also, I cringed when I saw Björk touch the metal of the tube...of course, since the TV was already ready to disassemble, I imagine that the CRT was discharged in advance, long in advance. Hell, maybe the TV is just a prop, I dunno, lol
That silly bit where you touched the anode and got 'zapped', ya got me with the unexpected loud volume; if you really had been zapped, we wouldn't of seen anything other than you retracting your finger (as well as spewing out a vulgarity slew lolz) and probably sucking on a fresh wound. I got zapped by my LCD monitor a few years back because I didn't have a grounded power cable for it and I touched the metal part of the display connector when trying to find it from behind. Left about an eighth-inch deep incision in my index finger, that did. Hurt for a damn week, to boot, akin to that of a deep wood splinter.
I'd rather feel the vibrations of a powered-off light switch plate than ever deal with ungrounded electronics again, lolz
6:50 I think this is a perfect jumpscare for me. I was literally shocked!
Haha you’re welcome?
It's a capacitor you did the right thing. Ground it to itself. The so called engineer is full of it perri.
Had me at "phophor coating"🤣
That spark scared the heck out of me. But your video was very clear and informative, so I'll let it slide. Stay safe ✌
Nice video Peri Sim...Chris Fra...err friend. I was about to post on your your May 11 video but then I searched the internet just to make sure I wasn't off my rocker and found no evidence that you needed to plug it in. So nice to finally see the explanation of why. I've discharged a few in my younger days and did have the plug in the wall with power turned off and then immediately unplugged it as I got to work. But yes, that does seem kind of dumb now that I think of it since if there was a problem with the on/off switch...zap. At least I was safe enough to not touch it with my bare hands and only had one hand on the unit. I swear back in the early 90's I had a Mac repair kit that came with a wrist strap ground that plugged into the power cord (i.e. it had just the one ground wire poking out).
I've actually started discharging my CRTs via a high voltage meter after once suggesting on Reddit that someone plug in the AC cord for grounding prior to a screwdriver discharge and being swiftly corrected. Logic being that a high voltage probe acts as a several mega-ohm resistor to the chassis, and provides a slow, no-spark discharge that you can watch via the needle on the meter. For some reason my logic prior to this was, "I want to be grounded, and I want the CRT chassis to be grounded so that we are at the same potential during the discharge" when in reality, if I had taken a second to think it through, I would have realized that I'd be at the same potential as the CRT chassis as soon as I'd touched it anyway, making a discharge without anything being connected to earth perfectly safe (and in fact, if I am *not* grounded, that eliminates a path through my body by which the discharge could happen anyway). Just one of those weird gaps in my thought process (and I studied electronics in college) that I needed some extra help to fill in.
Ahh... Reddit... 🤦♂️
I love this moment! NEW Retro Recipes Video ! WOW!
Awww 🥰 all the Little houses 🏘 🤗🤗🤗
Why did I just so much.
Like I've literally never flinched so hard from a video.
Scared the crap out of me when you did your little editing thing! I jump in my chair. LOL
"If Björk doesn't give you an ASMR, nothing will."
I was *very* afraid for her. I love her. Don't do that to my heart ever again.
(I love your channel
I´m forced to admit, even though I was following along your detailed explanation, I literally jumped backwards in horror when that spark happened. You got me good. I actually thought you shocked yourself for a second!!! Damn you!! :D :P
Anyway, thanks for making this video and for pointing us to a useful piece of literature on the subject matter.
Thanks for the shout out on ZZap! :D
It was nothing compared to the shout out I gave when I was actually zapped ⚡🤣
Hahaha, damn you got me there, I lumped. hahaha. This was such a good EP man. Fantastic. That smooth silky 12 cylinder engine you call a brain is really running at the top of its game. keep it coming.
Thanks for keeping a lid on the panic. CRTs are absolutely dangerous, and should be handled with care, but they aren't going to kill you if you don't make yourself part of the circuit.
they aren't going to kill you, I've been doing this since 1965 when I took classes in high school. problem is when you get shocked you jump away from it, I probably would have dropped a CRT but I was wise enough to have my dad help me load it into the car that day. I got a pretty good jolt but it won't kill you.
@@cat-lw6kq why was the case off
@@cat-lw6kq These feel like getting shocked by a horse fence
For all the people who think that both Chris and David or Jan Beta or many other people who are dedicated to this; they are wrong ... maybe u are wrong, because the physical Earth is not the same as the ground!
As explained in the video, is a CRT a large capacitor? Yes, but I prefer to call it a Leyden bottle. Of course, the Leyden Bottle is the primitive capacitor, so yes, it is a capacitor. And the CRT is connected to the ground of the device, not to the physical earth. All switching mode power supplies are separated into two sections, the hot area and the cold area.
The hot area is where they come from (without isolating, of course) the live, the neutral and the physical EARTH of your outlet. But the cold zone is isolated (in most of the time, in the old televisions there is a hot chassis and no, they are not isolated), but in modern Power supplys are isolated and there is a positive voltage, GND or 0V and, sometimes, a negative tension.
So GND Ground It is not the same as Earth. 0V is not necessarily the absolute zero but it is a return path for the circuit to close. These grounds are also called floating earths since what they do is to be floating a little above the voltage they should be at, 0 Volts . If you look in any psu, a most of the times a blue 1kv Y1 disk ceramic capacitor is located between Earth and Earth for high frequency voltages or transient parasitic voltages. If you connect the Earth with the ground, something may explode or blew up
6:51 i litreally almost fell of my chair you actually got me
Hearing Björk say "just swallow and swallow" made my day. Thank you.
Huh, peeps talking about what they don’t know, that’s never happened before. I was a trained electronics repair tech at one time and this is a tried, true, classic, sensible, informed, scientifical, and safe way.
When discharging caps I usually use a big resistor to go easy on a cap itself again it is a drastic way of doing that, 100 % effective tho I'll admit. To be honest I never was 100% sure where the charge goes if you short tube as you've shown, so I've always directed it to ground prong on power outlet....
you git!! i jumped out my chair when you got zapped!! HAHAHAH
Git. Now there's a word I haven't heard in a long time! Also, sorry 🙇
@@RetroRecipes absolutely no need whatsoever.. it really made me laugh.. thank you.. yes, Git is still widely said in the north of the UK or is it said widely?
And always discharge it to the CRT itself directly (the frame around the bell or the black conductive paint), and not the circuit chassis/ PCB ground, as some CRT monitors/televisions may have circuits that measure the beam current connected between the CRT bell and the main ground, and you might damage that.
I'm going to be honest, I find this video super satisfying and educational to watch, even though I will probably not work on a CRT.
I have an old rubber handle screw driver I soldered a wire to then heat shrink wrapped it up to the end leaving about 1cm then put a mains plug on the other end wired into the earth,in the UK we have 3 pin plugs I took the live and natural pins out just leaving the earth, I just plug it into the wall socket and discharge the CRT that way I leave it on for about 10 mins because they do have a habit of slightly recharging, I've had the odd small shock where I haven't kept it on long enough.
I always feel you're holding back with the "PCB Wayyy!" delivery.
Lol really?!
But with free global delivery you can bet they're not holding back! #ad
How can they 1) sponsor so many youtubers, 2) deliver stuff for near free? It is either a Chinese governement spying agency to collect electronics IP, or the TH-camrs are sponsored with almost nothing just like 5 free PCBs.
6:51 - THAT SCARED THE POSITIVE CHARGE OUT OF ME!!!!!!!! 🔋
Awesome video! Another safe way to allegedly discharge the tube is to let it sit, unplugged, for 24hrs. It will slowly discharge naturally this way. I make no promises. An unsafe way is to discharge it with your tongue while grounded. Don't mention this method to Björk.
Correct, over 1-2 days the energy dissipates into the environment. The screwdriver trick just speeds it up. 👍🕹️
Always been totally in love with Björk
She is kyuute, sure.
6:52 I almost had a Heart-attack!
First time I've seen anything from this channel-I didn't know Whispering Bob Harris had a retro tech channel! Nice.
Still haven't forgiven you for the finger slice joke.... Now 6:51 -- Jolted in my chair!
Sorry! 🙇
Tbh listening to bjork is super relaxing. About the discharge of CRTs, thank you for the info tbh, bc we all know how the internet works ad you can't be sure about nothing lol
I like how you teach something without being condescending like a certain other YT'er. :-)
As one of the people quoted in those responses, but NOT among those who suggested leaving it plugged in...
Those kids suggesting to leave it plugged in are thinking of modern day ATX power supplies that have a toggle switch on the back. The switch disables the power leads but leaves ground/earth connected. But this doesn't apply to old PSU's like a classic Mac, or anything else without that switch.
On the other hand... This whole video is based on a theory that shorting, with the heat and light from a small spark supposedly discharging an entire a lethal load, is better than sending it to earth.
It usually works... in theory.
You should be advising people to get their ground/earth wiring checked up to code by a licensed electrician, rather than merely insinuating their home is wired incorrectly.
I saw Bjork live, and she convinced me Magic is REAL...
Seems there are really entertaining repair manuals out there!
So many "experts" out there :-) Greetings, Doktor64!
Jeez I jumped on the chair and I shivered during the fake Zap!
Jeezoos, I watched this again and AGAIN, I jumped on the chair, darn! LOL
I took my TV apart in the 90s and stuck my finger under that plug thing your sticking your screwdriver in on the tube and it gave me a right bloody good electric shock! Damn hurt, I thought I'm never gonna try and fix a TV again! Also once my dad had bodged cable extension onto our TV and sometimes cause it was loose the TV used to lose power so I tried to fiddle with the junction block one day whilst it was plugged in and got 240Volts through me...Pow, I flew across the living room!
Yes, CRTs are capacitors, indeed. But its not the electrons themselves that are converted to heat or light when you short a capacitor, it is the _potential energy of the charge_ (electric potential difference between poles). The electrons are simply rushing from the negative pole into the positive one, releasing energy. Also, not all capacitors have fixed polarity, as you implied early on, that's electrolytic capacitors only (including tantals etc).
Only your voice gives me tingles, my king !
Nice cracking vid!
Happy what you unearthed your findings pointing the risks of beeing the referance ground!
Other wise Robin would say holey smokes Batman!
Before watching this video I envisioned a mushroom cloud forming over the remnants of retro recipes headquarters... a good thing turned out far less drastic than imagined. :)
Björk... she was touching.... oops....
I spilled an entire cup of coffee over myself at that fake zap
This is the best video I have ever seen.
I can still remember my old electronics teacher in High School Mr. LaSavio ( who wasn't allowed to call us idiots, so he called us Quiche eaters!) showing us how to work on CRT TV sets (yes this was a long time ago), of course me being the know it all was working around the fly back transformer with a large screwdriver. I then proceeded to short the cathode on the picture tube with said screwdriver, resulting in me being blinded and thrown backwards across the room! Then you heard across the room a very angry Mr. La Savio yelling "You Quiche Eater!"
I looked pretty stupid on top of a crushed trash can ( yup, it was a metal one) holding a melted screwdriver!
You just solved a problem that bugged me for a long time. Thanks
and you just gave me a slight heart attack here 6:50
The negative is the painted on, black coating on the outside of the back of the picture tube. It is called an aquadag coating and conducts electricity to the chassis!
Very nice job done sir. You got my heart blown.
You got me with that 6:52.
Sorry!
Oh, you pulled an ElectroBoom :)
I learned something from that video. Thank you.
Same thing with PSU. Pull the power cord when it's turned on. You will see that the energy is gone. But of course short it too if you can't wait for days. Measure before doing anything more.
Very useful advice from Bjorkyfractic and your good self 😊
Yes, I've learned something new :-) Every day's a school day! That ElectroBOOM moment though, gave me a jolt like I'd just touched the tube!! Thank's for potentially saving my life ;-) Oh and love Björk, she's as mad as a hatter and the world is a better place for her.
Long live Electroboom
Thanks for that! I've been wondering why all the TH-camrs were doing it "wrong" but it seemed to work anyway...?!? LOL
«GOT THAT! OUT WITH THE CORD!» cause «I ain’t got no time for fools, Sucka!” @Nostalgia Nerd’s quote of Mr.T!!
Admittedly, trusting my life to the opinion of a stranger on the internet is not something I'm eager to do.
6:50 - almost got a heart attack, thanks
6:50 Oh you bastard, you got me good there lol
Where did you find this Björk footage? It's... just... priceless!
Good question. I had known about it for many years and had always wanted to do a video about CRTs. The two just came together finally.
Thank you. I love the application of fact over a knee-jerk reaction based on insufficient or inaccurate information. :-)
I couldn't have said it better Pauline 👍🕹
You're very welcome. Can't wait to see it all finished. :-)
"I read that in a Danish book.... this morning..."