Hope the video was helpful! If you need some tools recommendations check below Quality meter to test voltage of capacitors - amzn.to/3x7P5eL High Voltage Discharge Stick amzn.to/3x4BuVt Drivers to use around high voltage - amzn.to/3j8zweN
Question: Blower unit capacitor in my Bryant forced air heater might be bad. So… before I attempt to remove it, how long after cutting off all power to unit, will it take to discharge on its own? An hour? A day? Thanks in advance for your response.
@@john-robert1961 Not sure, but if it was me I would turn it off. Then go measure it with my multimeter. Then I would wait a few minutes and check it with my multimeter again (voltage setting). See if it's discharging on its own and how fast.
@@HTMWorkshop thank you kindly for your rapid response. Naturally, I would turn off the main wall switch that connects to the unit, before even attempting to test anything. I will do the voltmeter test, followed by the capacitor test. I’m glad that I have encountered your video earlier this evening, it’s very informative.
@@john-robert1961 Back in the day, it's amazing how many people went POKING around (INSIDE) those old VACUUM TUBE TV's with a SCREWDRIVER!🤯😁😆😂🤣😂 BEFORE properly discharging the Capacitors! What a SURPRISE they received!😆😂🤣
Electrical burns can definitely hurt. Hope your ok, glad your learning from your mistakes! “The only real mistake is the one from which we learn nothing.” HF
@@HTMWorkshop it still hurts after 1 day and I have a massive boil but I still need to see how to discharge these 450v I work with I repair consoles and they have 2 of these big capacitors I saw something on the internet to connect a light bulb to alligator clips and discharge it that way but I wasnt successfully in riggin something up so I just used the old screw driver but they discharge extremely dangerously in my opinion and I dont want to blow one up in the system.....
@@176cgna Yeah a screwdriver is just releasing the energy very quickly (and that means things can get hot), you need a good high Watt resistor (and decently high resistor, depends on how many Farads you are dealing with and how quick you want to discharge - has to due with time contact of an RC circuit). Most incandescent light bulbs are rated for 60W, and have a pretty low resistance of 120 ohms, so for a 450 V source you are roughly looking at around 3.75 Amps (most bulbs are rated around 0.5 amps). So not a great solution for high voltages. Some places sell high voltage discharge sticks for about twenty bucks if you want a profesional solution. But if you can find a high watt (2 W or greater with a resistance of around 100 kohms, that should work, just may take a while to discharge depending on your capacitors)
@@HTMWorkshop ah ok ima look for that tool I dont care about price and I work with these capacitors enought to warrent the purchase of a professional tool
My trick for those 200V or 400V capacitors is to use a lightbulb with wires soldered to it and just discharge it using the bulb, best to use an old fashion one with wire inside it, really useful when you are dealing with such voltage.
For as long as I can remember, my dad keeps a lightbulb on some wires in his tools, which he uses to test circuit completion when doing house electrical work. Of course he first finds the live phase with a tester, and then checks with the lightbulb to be sure the ground is also connected. Why not use a voltmeter you say? Well he says, "I don't have a third hand to hold it with".
@S Wong it can but only for low current situations! Most LED's can take around 20mA so you do not want to exceed the max current (or else your LED will turn into a fuse - which is not the end of the world since most LED's are cheap but it may fool you into thinking your capacitor is discharged when in reality you just fried the LED).
I came to send this video to my neighbor. I once saw a dog lick a charged capacitor by mistake while a parent was getting tools to repair an opened microwave. The dog was flung off and hurt pretty bad. It stuck with me. I was walking by this morning when I saw a guy taking a microwave apart. I asked if he discharged the capacitor first. When he said the what now? I told his wife please get him away from it. He will get hurt! I then sent them your video. DAMN People! Come on!
Great video! I wish they explained things this well when I was in school. They probably did I just didn't get it at the time. Age is not always a bad thing! Thanks for the info.
they cover it indirectly if that is of any constellation. For my CompTIA A+ they said that if you get trained to work on televisions you will be taught how to properly discharge the capacitors, then in electrical they explained the relationship between resistors, capacitors, and time. Then throughout electrical they regularly explain that oftentimes steps often considered not recommended are the safest way to do tasks while implying that shorting a connection is sometimes the case. Never once do they explicitly teach anything about properly discharging a capacitor but by the end you have tons of hints. So for this reason I am very happy to learn the specific recommended process for the first time and as such I would very much like to thank the video author.
I really learned a lot from this video and I sincerely thank you. I hope you make a video teaching how to safely discharge a higher voltage capacitor-not necessarily the 2100V type, but the 200V to 400V range might be helpful. For reference regarding the 2K capacitors, it may add perspective for people to realize that the electric chairs used in the electrocution of condemned prisoners typically delivered around 2,000V. Granted, they were higher amperage (7 to 10A) and the charge was delivered for several seconds, but it gives us an idea of the seriousness of 2,000V.
Always cut the trailing ends of strings off when you change them was good advice I was given. 1: So you don't blind someone and 2) They can penetrate electrical equipment!
I've been dealing with caps for decades, so I didn't learn anything new from the video, but I was highly impressed with your teaching style, calm and steady and looked like you prepared well. It is obviously aimed towards beginners, and you reduced the topic to its essential elements, and explained them simply. I was hoping to see what you had to say about BIG caps, I worked at a 500 Kilowatt shortwave station. Can't say "my loss" as I enjoyed watching your video. 73deK1WXY
Anything involving high voltage. Current transformers...If the secondary has no load, the secondary voltage can soar to very high voltages. Won''t explain why here, google it. Large batteries...Watch your jewelry. If metal watch band or bracelet shorts out a large amperage battery, you will not be electrocuted, but may get an impression of the jewelry BURNED INTO YOUR WRIST. Can and has happened to people reaching up under the dashboard fiddling with stuff up under there. A ring contacting the battery terminal on the rear of the starter switch melted a friend's wedding ring into his finger, ouch. Any one else got any suggestions?
Very good video and explanation, i once thought about touching one of capacitors even though it was only 25v and at that time i didnt know what those things were and well i have to say thank god i didnt touch them and thank god it wasnt a high voltage capacitor (didnt know what was going through my mind at that time xd)
Thank for the knowledge sir I really appreciate it. One of my relatives son telling about his experience about electronics and then he told us about capacitor thing and tell us how dangerous it can be that's why I am here to gain knowledge.
I have three microwave capacitors rated at 2100V sitting around my house not yet discharged! Just realized I'm lucky to be alive, and that is why I am watching this video.
Usually, they have resistors built in to discharge themselves. But, it's always a bad idea to rely on one point of failure with big caps. Capacitors can also spontaneously develop a charge to do dielectric re-absorption. I personally like to keep them permanently shorted out with alligator clips like that, just in case!
I use solder wick to discharge or verify discharge if not in circuit. I have a 8 Ohm 10 W resistor (used for ESU testing) I use for board discharges (with jumper wires of course)
🤔Interesting. I have not used solder wick for that application, but I see n no reason not to as long as you are ok with a quick discharge. Nice tip if your doing board work and some handy. The 8 ohm resistor would definitely be a good discharge resistor. Out of curiosity what test are you doing on the ESU with the resistor?
I have read through some of the comments. I have worked around 400 volt lines and higher as a research scientist. Around 400 volts, there is an invisible charge cloud or corona about these lines and devices connected to them. If one is grounded, burns, neurological and brain damage and death can result without direct contact. An kindly older electrician told me this when I was 24 or 25. He saved me injury and death many times over.
Good point - yeah I use to work with 1-10kV and your right (everything even air becomes a conductor at some point and ions can form). I use to do some electrospinning back in the day, and it takes advantage of that very effect.
Thanks - depends on what type of power the potentiometer can take. The resistance is good - but if you run to much current (at a high voltage.. remember Power = current x voltage) then you may burn up the potentiometer. I would not recommend it for discharging very very high voltage things - but my guess is for most applications it would be just fine since it is just a high resistance - and therefore low current.
Thanks for this this informative video! I need to remove a very old high power xenon lamp igniter and want to do so safely and not get knocked on my butt!
Thanks for the video. I’m looking for an example that explains what size resistor is needed, or should be used with, the capacity trying to be discharged?
Hmm - I don't exactly have a video on that. I do have a blog that may be helpful here htm-workshop.com/how-to-discharge-capacitors-safely/. Also I know in a couple of the comments for this video I explained some specific resistor choices for caps. The key is understanding the power the resistor can take and how fast you want to discharge the cap. P = IV or V2/R , so don't exceed the power rating of your resistor or you will fry it - also the time it takes is based of the time constact for a capacitive resistor circuit ruclips.net/video/JcrlL8YN6VQ/видео.html. A 10W 1MOhm resistor may be a good place to start but it is very conservative (for most circuits)
Also, as a note, that resistor is 5 watts which means it can take higher power. (Little resistors are 1/4 W or even 1/8 W. Not sure what surface mounted ones are rated at.)
Haha hey, you have the same oscilloscope and multimeter as me lol. Always nice to see another Tack Life user out there. In my opinion they make pretty great equipment for the low cost they charge.
Hello, great video. A question: is it enough to have any resistor to discharge any capacitor ? I mean, can I have only one size so I can use it with a small capacitor or with a large one ?
resistance too high and it won't discharge. resistance too low and it will melt or catch fire. it matters, you can't just use any. it will depend on both the voltage and the capacitance of that specific capacitor.
Theoretically yes if pacing is not needed (there are some arrhythmia that require shock to be delivered at a specific time). That does not mean it's a good idea - since in practice you would want to size the capacitor correct, make sure there is appropriate contact with the skin (so as not to burn the body), make sure you did not discharge to much power into the power. It is possible but not advisable. Also there are different waveforms that are better than others for starting the heart - but a single capacitor can not control that. So in theory yes - in practice no.
@@davidvankeuren6575 My wife and I had been discussing repairing our microwave oven as a DIY project on an old GE Spacemaker 1400 microwave. After reading about multiple instances of fatal microwave repair projects; we've decided that it will be safer to take it to an appliance repair shop. I am sorry to hear about what happened to your friend.
This was some great presentation of information thank you. I am not strong in electronics but I am studying up to disassemble a digital camera that has a flash, and the manual states to discharge before taking of a certain part at these points. However it does not state which items I'd need. From my understanding are these ceramic resistors so big that I can order the same one I see you use or another video that I should be okay to use it for most "safe" capacitors, or do I have to do some math to match a capacitor every time? I guess my question is more of an is it "a rule of thumb" question, as I'd assume its always safe to calculate what you're working with.
Good question - I don't have a good rule of thumb for which resistor to select - if you select one that is to high it may take forever to discharge and if select one that is to low your going to pull too much wattage (and fry your resistor or worse). I recommend calculating the power and the time constant if your going to discharge things yourself for high large voltage large farad caps. But if the voltage is below 24 (or even 100 V) in most cases your not in trouble and if the capacitance is in nF or uF that is pretty low so it will discharge pretty fast. I don't work around a lot of equipment I am willing to do general rules (to expensive to replace) but if the equipment is not to expensive I would use a 1 Mohm high wattage (20 W resistor) or something like this amzn.to/3yIYoRx. Hold that on the leads to discharge for a little while, then check it with a multimeter to see how much voltage has dropped, if its going to slow get a lower resistance and try again. Hope that helps a bit.
Thanks! What res is recommended and up to what voltage cap? And is it alright to touch the leads of that res when doing that? Also is a discharge pen recommended for higher voltage?
That depends a lot on the situation - for instance do you just want to discharge the capacitor or do you care about keeping the circuit integrity and capacitor working afterwards. A very consdervative basline is around 24 V - I don't mind touching 24 V shorted but if you discharge a 24V cap fast it may damage the circuit around it (depends on the situation). In practically I wouldn't mind discharging a 500 V capacitor if it had a small capacitance and a insulated handle - but that is getting more risky and could easily damage the circuit. It really has to do with your risk tolerance and what your comfortable with but always best o err on the side of safety if you don't have a good grasp on the circuit and your own risk.
One thing you forgot to discuss, is dielectric absorption. It can cause capacitors that have been discharged to regain some charge after some time, amd could lead to a nasty surprise.
Do the microwave capacitors tell you how long it takes to bleed out that voltage once they are unplugged? I'm guessing a few seconds. Still makes me nervous.
I don’t think the manual will tell you...but your probably right. Assuming all is working correctly. Best to unplug, check with a voltmeter then do a quick discharge to be extra safe.
@@raybradshaw8444 It would depend on what kind of wattage the resistors could take. Maybe a 1 MOhm resistor ... but it could take some time to discharge depending on how many farads. Often you see 100 kOhms used in high voltage discharge sticks.
@@HTMWorkshop as a basic sum it took 15sec with a 50kohm (3 R in a sting) tool on 300v, and 30sec with a 100kohm (6 resistors in a sting) on 300v, so dum math says 300secounds with the 100kohm so 5mins for 3000v. i just dont know if my little 100kOhm Tool will handle 3kv and not melt like a icepop, lol
@@raybradshaw8444 It just depends on what the resistor is rated for power wise - is it a high Watt resistor? The higher the resistors the slower the current will move so you can use lower watt resistors (its a tradeoff between power the resistor can handle and time it takes t discharge). You have to check both.
I never discharged a capacitor by shorting it with a screwdriver. Instead, I used a 40W incandescent lamp with a bare wire. I connected this lamp to the capacitor terminal during which it will light up briefly and then fades
Great video, would have liked to see how to test the charge. I know you can use a multimeter, but they are very sophisticated alien-like devices. I don't know what setting(s) are proper for what scenarios.
Thanks - by charge were you interested in measuring voltage or capacitance? You can check out this multimeter video on our channel if you want ruclips.net/video/BxVbLKd5Kk4/видео.html
@@HTMWorkshop I'm just concerned about residual electric during electronics repair thru simple replacing of parts. For example, people say computer power supply units can have a deadly charge in them for a long time. How can you really know without testing them? I assume that's the only other major thing to look out for, aside from making sure the device is unplugged of course. Thanks for the link.
@@lakecityransom I have worked on quite a few computers - I have not seen to many capacitors dangerous enough to pose an issue. I have often heard that if you disconnect the power then hold the hard reset for about 10 seconds you can discharge any remaining charge in the supply - but I would be surprised if that was even necessary. I would be more worried about damaging computer components through ESD than getting shocked by a computer that is unplugged - most everything in a computer runs on low voltage - except the power supply. I mean it's possible you have some sort of super cooled computer with crazy fans and motors that are not normally included but most parts are low voltage. If your just changing boards or ram you really don't have to worry about getting shocked (just unplug the power cord since the line voltage is the only real thing to worry about). Now I am assuming your not dealing with a CRT screen computer - if you have a computer that old then yes you do need to worry about a high voltage capacitor (but only for the CRT screen).
@@HTMWorkshop Oh for sure I've worked with computers a lot. I actually mean working within the PSU unit itself. There are cases of teenagers dying if you Google on that. The most common reason to open one up is the PSU fan's bearing goes bad and starts making a lot of rattle. Its simply a matter of replacing it with another standard 80mm or 120mm case fan. However, you do have to open it up and all the parts are in there tightly so it is concerning to attempt unhooking one and putting the other one in. I replaced a water intake control on a washing machine the other week and was questioning once again how safe I was being without testing components for residual electricity, but I did get the job done lol...
@@lakecityransom Yes it is possible - many psu utilize capactive reactance to step down mains - I believe those are suppose to be designed with a bleed capacitor - but I am not sure. You should be ok to replace the fan - just be careful around any caps that read over 20 V. I would imagine the fan should only have a couple connections or more likely a single molex connector. Which should be safe to unhook and change out. If you want to be extra safe you just make sure to take your meter and put it into voltage mode - then measure across the capacitor legs - and make sure the voltage is low. Always good to take of jewelry and use one hand as much as possible to reduce risks but I would imagine its fairly safe unless your really messing around near the caps (and even those should discharge pretty quick if the circuit is setup correctly).
Awsome video although I like to have the same setup you have transformer and rectifier can you posted the design setup so I can do the same on my little lab. appreciated... thank you;.
to be honest I am not sure - wish I could be more help. you should be able to use any DC supply and high voltage transformer for the type of walk through shown - but if you needed to worry about power/current of the device that may get tricky to make sure you down draw to much power.
Yes in general, if you had multiple sources for example you could use 200 V sources you could put them in series to create a 400 V source - but your still ultimately using a 400 V source
iit is not because the max voltage supported by the capacity is 400V that you will charge it at 400V, this is the max allowed DC + AC ripple voltage supported by the cap.
Good question, depends on how how fast you need to discharge the capacitor. Time constant is a key factor to determine how long it will take, time constant = RC. So if you had a 1 uF capacitor and a 1 MOhm resistor it would take 1000 seconds. You can always use a lower resistance value but then you have to make sure you resistor wattage is not exceeded. P = IV or Vsquared/R. So if you have a 1000 kV capacitor and a 1 kOhm resistor you would be dealing with 1000 W! if you used a 1 MOhm resistor you would be dealing with 1 W. High resistance value are safer in a sense but you have to make sure you wait long enough. Hope that helps
@@HTMWorkshop Thank you, but i'm still a little confused. What unit represent Time constant (second?), R (kOhm or Ohm), C (uF or F), V (kV or V), and what is I? Let say i need to discharge a 400V 60uF capacitor in 60 seconds, i'll need a 0.4W 1kOhm resistor? I can't seem to work out the formula, can you help me with that? Thank you very...very much.
@@mrdzin1209 Time constant is in seconds - you have to make sure R and C are in the base unit (ohms and farads). I is current. You will discharge that capacitor much faster than 60 seconds with that setup but you will need a 160 W resistor (I am doing those calculation pretty quick but I believe that is correct). You probably are not taking into account the unit prefixes for the first part. For the power calculation you need to make sure you square the voltage and then divide by resistance
@@HTMWorkshop Thank you, it's very helpful. And you're right about my setup, it would need a 160w resistor and discharge in 0.36 seconds (so a 16w 10kOhm resistor in 3.6s would be much more efficient). I believe you do that calculation in your head and that's freaking amazing.
Sounds like you got it, always a good idea to check with a voltmeter after discharging to verify. Or if that is not an option use a screwdriver to discharge any remaining charge (better to have a damaged board than a damaged hand)
@@HTMWorkshop Thank you! If the wires of 1 resistor are not long enough, could I use 1 wire from 2 different resistors to discharge the capacitor still?
@@grooty6434 Im not exactly sure what you mean - you can use two resistors in series - yes. There must be a path between the leads of the capacitor - what you put in between determines how fast the discharge (based off resistance mainly) - see more info on time constant of caps for how long it will take
You look like a master. Can you just point me in the right direction? I have a Mark Levinson no.27 amp. When I turn it on I heard a strong pop on the right speaker and then the unit went into protection mode. Even time I turn it on after that the power switch would pop back to off. Same result with all cables off with only power plugged in. The power light still lights, fuse is good. Can anyone give me some guidance? Thanks
Not sure on that one - sounds like some sort of current issue. Honestly, I would be looking in the user manual to see the reason for protection mode - start narrowing them down one by one to see if any of the suggested corrections work. My guess is you may have already tried that but can't say I'm familiar with that amp.
Wanted to ask a question in regards to discharging using a ceramic resistor like you did in this video, I noticed when you were discharging you still had part of your finger on the metal bit of the resistor, Is that safe to do so?, Also does it matter what polarity the resistor is to the capacitor?, I'm assuming it doesn't have polarity and doesn't matter which way you discharge it, whether its face down or face up. Lastly do both the legs of the resistor have to make contact with the legs of the capacitor at the same time for discharging? TIA
Resistors do not have polarity and yes both legs of the resistor must touch both legs of the capacitor to discharge. As far as if its safe to have your finger touch the metal part - the answer is maybe but best practice is NOT to touch it. Certain voltages are perfectly safe but if you are not that familiar with safe voltage I would just stay on the safe side.
why not use resistor to discharge capacitor that has high voltage if you are holding the ceramic part? what would you suggest to use to discharge over 1,000 volt capacitor when usually equipment insulated for just 1,000? thanks
You definitely can use a resistor but you need to make sure you get one with an appropriate wattage rating. You can reduce the power with a higher ohm resistor but then the higher the resistance the slower the discharge. I would use one of those high voltage discharge sticks I have in the description otherwise you can size out the resistor you need if you have a bunch of high wattage one - but for most people they don't want to bother with doing the calculation
Do you have to touch both leads / connections of the capacitor? And the shock happening in what is between the leads? Or is it a matter of charge being able to go to ground? In which case, is only one of the leads actually dangerous (the one with electrons at it's disposal to send out)?
Usually, yes between leads. Touch current is going to be negligent unless one of the leads of the capacitor is already grounded (in which case if you touch the other lead it can still discharge). In other words caps are not by nature grounded but if you connect one lead to ground then the other lead is going to be dangerous (if its at high voltages)
What about using gloves to prevent shocks/electrocution? Like those that linemen wear for their work. These gloves might be too cumbersome to wear all the time but I imagine they could be useful to have when in doubt
Yes you definitely could - but you can still damage the electronics if you are discharging the cap near the board. So that only works well if you either don't care about the device or if you have already removed the cap.
I have an old shortwave diathermy machine (Mettler 300) that seems to be malfunctioning, tubes seem to get hot (tubes have been changed as I first guess) but the coil doesn't seem to be hot. Under the lid are 2 separate capacitors (each set has 5 separate 28pf 5kv in joined parallel -- for 140pf 5kv each). I suspect these capacitors failed. To the look everything else seems okay and to the eye some capacitors appear to have cracks in them. These capacitors (10 in total) are ceramic disc capacitors. Warnings on the inside of the equipment to not work on it. No videos/aricles anywhere on how to discharge these. Machine has been unplugged for months.
Could be the issue, very high voltage. Yeah a lot of manufacturers say not to work on their equipment - this is more of a legal issue that a technical issue. The OEM is trying to protect themselves legally more than anything. I am sure they would tell you only a certified person should work on their equipment and tell you that it costs thousands of dollars to take the training. The capacitors are probably are not charged up, but better safe than sorry. I would use a high voltage discharge stick to see, ideally with an indicator LED. Then you can use your meter to confirm no voltage and try the repairs. But of course the OEM warranties and such will all be invalid but I am guessing that is already the case. I don't know who you work for but obviously they would need to be comfortable with the repairs and risks of repair.
You kinda made me feel at ease saying "it wouldn't be a serious shock" but I know I should still be cautious. I came from a microwave video and that thing is 2100V.
So I have 4 Caps that are in the power supply circuit of a stereo processor. It's 19.5V AC feeding 35V 470uf Caps. I need to replace them as a few have begun to leak. Do I need to worry about discharging them before un-soldering them from the circuit?
20 V is pretty safe, 35 V is still pretty safe but on the edge of possible issues. I personally would not worry but if you want to be extra safe I would just use a screwdriver to discharge them (or some other piece of metal)
Not sure - depends on who made it and how well it holds up to the stress of the discharge. You can always charge it back up and see if it holds a charge. Very well could still be good - do you see any visible damage? What are you using it for?
My only accident when I opened a throwaway film camera with flash. I wanted to see what it was like inside and I shorted the cap. That was interesting.
Same happened to me, disassembled one to play around with the flash with my brother and I guess I shorted a capacitor, because I got quite an interesting shock in my arm
Great video. I now realize that I may have gotten very lucky by not killing myself with the microwave capacitor I have been handling. I'll be much more cautious with those in the future.
Update: I also realized that I smashed the hell out of the Bryllium ceramic surrounding the microwave magnatron. I didn't die immediately from Berylliosis, but I probably took 30 years off my life. Happy scrapping folks!
Can’t you just wait a certain amount of time and they’ll discharge? I’m going to recap a Nikko amp and it will be unplugged for at least a week. Can the big caps hold a charge that long?
In most cases that can work but in some cases the cap may be very big and the discharge may take a while. In some systems there is not a bleed resistor to help discharge the cap when the device is off (depends on the device and application)
If you disconnect an amplifier (ie: 500w ClassD stereo and/or subwoofer amp with toroidal) approx. how long till all the capacitors discharge to a safe condition all on their own?
It depends on how big the capacitor and how big the bleed resistor is... best thing to do is measure it with your multimeter in voltage mode to see if there is any charge left
what about 50v 6800uf capacitor? got 2 of those and 4 25v 1000uf capacitors in an amplifier board that i wanna take apart. it hasn't been plugged in for months
Well I would think the capacitors probably fairly safe (but that is a guess I don't know what your board looks like) - I would just check them with a voltmeter. If they read 0 volts then you know they are already discharged. If not, use a high ohm resistor to slowly discharge them to protect the electronics. My guess is they are already discharged.
Well, I assume you mean in an off state (meaning not used to power anything), in that case it depends on the amount of leakage current. So if you had 1 Farad of capacitance fully charged you could figure out the time constant using t = Resistance * Capacitance. So you would need to know the effective resistance for the leakage circuit. Then multiply the time constant by 5 to get the effective discharge time...or you could just charge it up... then measure the voltage over time and see when it starts to drop (more of trial and error type method). Here is a general video on the time constant if your interested ruclips.net/video/JcrlL8YN6VQ/видео.html
@@HTMWorkshop it’s an Xbox brick power supply I had to ask first ! 2 in there are 200v 450f and 4x 16v capacitors as well ! Did not know if over time or if I needed a resistor to drain them but it did over time apparently
Well if you calculate the power at 450V and 220 ohms I get 920 W - so your going to exceed your resistor power capacity - choose I higher ohm resistor to reduce the W
V = I * R --> I = V / R P = I * V --> P = V^2 / R P = 450^2 / 220 = 920 W R = V^2 / P R = 450^2/25 = 8100 ohm So, you need at least 8100 ohms to safely discharge that capacitor. Just get yourself a 10,000 ohm resistor and that should do it.
Whoa hey you need to amend this video full stop. To whoever ends up on this video looking to discharge a capacitor, DO NOT EVER TOUCH THE LEADS WITH YOUR BARE HANDS--- NO MATTER WHAT THE SIZE. Never, never ever ever holy shit. Ok let me clear somethings up here for those who happen to watch this and notice this comment: 1- A volt wont kill you. Voltage is best explained along with amperage when trying to be practical about it. This explanation isn't accurate from a scientific standpoint per se, and I wont go into the science here, but for the sake of what happens to you when you're electrocuted, I think this works great and it's practical: An amp is the actual electricity. Imagine a marble, that's our amp. If the marble is on the ground, holding still, we're at zero volts. That marble won't move. Now I lift the marble and drop it. Instead of thinking of how high and comparing that to voltage, instead think of the voltage as "how hard" that marble hit's the ground when I drop it. So, 10v wont hit very hard, but 120v or 240v can hit you hard enough to blow you off a ladder. But, that "how hard" part can't kill you without the amperage(marbles), which is what's actually dangerous. If that marble is on the ground at zero volts and I were able to somehow reach down and grab it, I'm gonna get messed up. 1.a- 1 thousand amps at .001v will kill you dead- full stop. Like a steam roller moving slowly and, if you can conceive it, softly over your body. I mean it's not really slow or soft obviously, this shit moves at the speed of light in reality. But you get the idea here I hope. You're still 100% dead. But .000000001 amps at 1 Million volts probably won't do terribly much to ya in the end. That's like just one of the tires off of a micro machine toy hurled at you really super hard and fast. Probably very few scenarios where that kills you outright yea? Though, and this is important, don't take that for granted either because the electrical system that keeps your body functioning isn't insulated. We're made mostly out of water and we've all got a pretty good salt content so our bodies are pretty great conductors. And our super exposed electrical system that keeps us ticking doesn't like disturbances. Like....at all. Amperage is why I suppose I don't need to list anything else to explain why you don't mess about with capacitors if you're not 100% certain what you're doing. That loaded spring allegory that he used was kinda on the money, but that spring is amps. A capacitor discharges amperage. The voltage on a capacitor is irrelevant when considering how dangerous it is. They're all dangerous. A 10v capacitor has enough amperage to disrupt the sinus rhythm of your heart without you feeling it or noticing it. You can put yourself in A-fib without noticing it until it's too late. You can compare you're heart to a blower fan on a furnace. Our sinus rhythms(the full process behind each heart beat) are like the balance that is in place on those fans. If those fans end up off balance, the motor will eventually trash itself. Same goes with your heart. If you disrupt your sinus rhythm, your heart will start to break down and it will eventually fail prematurely unless it's caught during a physical. In which case, depending on how long you were in A-fib, your heart may be so badly damaged that you require extensive medical treatment ranging from ablation (where they have to open you up and make little cuts on your heart and then try to shock it back into rhythm), to a pacemaker and if you think your insurance is going to make that process easy for you.... well... that should go without saying, no? Also, the average survival rate after that point is about 5 years. And, speaking from what I've personally witnessed, you can walk around for a good 10 years being in A-fib without being aware of it or even having a doctor noticing it/catching it and that's about all you need to completely trash your heart. So don't touch capacitors with your god damn fingers. Don't do it. You don't need to feel the shock for it to kill you. I can tell this poster is pretty experienced and definitely very knowledgable , but man I wish they were just a little bit more concerned about the potential for life altering mistakes/death involved here. And, honestly, if I were you OP I'd go get an ECG asap if you've been touching these lower capacitance capacitors on the regular. All it takes is 1 shock to throw you out of rhythm just a little bit. And that little bit has a snowballing effect in the end. And, again, you don't need to be able to feel it. Also, don't discharge anything over 50v with a screw driver. They make capacitor discharge pens that are tailored for different size capacitors. Those are a pretty safe bet. Another option is to simply disconnect the capacitor and leave it be for a while. You'd have to look up the time needed for the size you've got, but eventually it should discharge on it's own. However, the only way to tell when it's done discharging is to either test with a voltmeter or a discharge pen. Hope I didn't come off so abrasive here that my points were lost, but OP, for really reals man, I'd go see a cardiologist if I were you just to get checked up on. It's not a guarantee that you absolutely will throw off your hearts sinus rhythm with a shock, no matter what size, but it is very much a possibility no matter how small that shock is and that's all you need to properly fear these components. Honestly, it's the small shocks that you don't immediately go to the hospital for that are more dangerous than the big ones that knock you out. At least when you're knocked out and you wake up in the hospital, they've already made sure your heart's working normally. Bit that little nip from that low voltage system that you didn't even think about could be a ticking time bomb
If by safe you mean for people, yes it is relatively safe for the the operator. However depending on the board electronics you want to be careful not to damage any part of the board. Make sure you understand the function of the capacitor before discharging to be safe for both the operator and the device.
who watched this after got shocked by a capacitor ? LOL I was trying to fix my laptop charger, and got shocked and indeed the capacitors are responsible for that. I am gonna call 911
By "touching it" do you mean touching both terminals at the same time, or getting shocked by only touching 1 terminal. Can you be more specific? I have an Ampeg svt I am going to take to a tech but I need to educate myself and do it eventually.
You could potentially get shocked by only touching one terminal. It has to do with potential difference - so if you touched the terminal that is at a high voltage with respect to ground (aka the potential of where your touch feet or other path to low voltage if another part of your body is touching something). Current would travel from the touched terminal to the low voltage drain. This is one reason that people where high resistance rubber shoes or something of that nature to reduce the chance of large currents running through your body. It's also why line workers (or birds for that matter) can touch high voltage power lines and be safe (there is no easy, low resistance, path to ground). If you need to touch a lead on the capacitor the best thing would be to drain it first, then verify there is no potential difference with a voltmeter.
Is there a reason they don't put some kind of international hazard warning, like a skull and crossbones, or at least a stop sign, on all high output capacitors?
Well its hard to draw a line in the sand and say this one is hazardous and this one is not - depends on a lot of factors. Its a good idea though and I do see some high voltage stuff marked (not quite like that but definitely a hazard warning)
The microwave capacitor shows 0.7 uF. I know the voltage is high (if charged high), but the capacity is low (?) even if the miniscule time period is enough to stop a heart. Please comment. Thx.
Hope the video was helpful! If you need some tools recommendations check below
Quality meter to test voltage of capacitors - amzn.to/3x7P5eL
High Voltage Discharge Stick amzn.to/3x4BuVt
Drivers to use around high voltage - amzn.to/3j8zweN
Question: Blower unit capacitor in my Bryant forced air heater might be bad. So… before I attempt to remove it, how long after cutting off all power to unit, will it take to discharge on its own? An hour? A day?
Thanks in advance for your response.
@@john-robert1961 Not sure, but if it was me I would turn it off. Then go measure it with my multimeter. Then I would wait a few minutes and check it with my multimeter again (voltage setting). See if it's discharging on its own and how fast.
@@HTMWorkshop thank you kindly for your rapid response. Naturally, I would turn off the main wall switch that connects to the unit, before even attempting to test anything. I will do the voltmeter test, followed by the capacitor test. I’m glad that I have encountered your video earlier this evening, it’s very informative.
@@john-robert1961 Back in the day, it's amazing how many people went POKING around (INSIDE) those old VACUUM TUBE TV's with a SCREWDRIVER!🤯😁😆😂🤣😂 BEFORE properly discharging the Capacitors! What a SURPRISE they received!😆😂🤣
I just discharged a 450v to the palm of my hand let's say I have 2 boils now and pain.... that's why I am checking this video out....
Electrical burns can definitely hurt. Hope your ok, glad your learning from your mistakes! “The only real mistake is the one from which we learn nothing.” HF
@@HTMWorkshop it still hurts after 1 day and I have a massive boil but I still need to see how to discharge these 450v I work with I repair consoles and they have 2 of these big capacitors I saw something on the internet to connect a light bulb to alligator clips and discharge it that way but I wasnt successfully in riggin something up so I just used the old screw driver but they discharge extremely dangerously in my opinion and I dont want to blow one up in the system.....
@@176cgna Yeah a screwdriver is just releasing the energy very quickly (and that means things can get hot), you need a good high Watt resistor (and decently high resistor, depends on how many Farads you are dealing with and how quick you want to discharge - has to due with time contact of an RC circuit). Most incandescent light bulbs are rated for 60W, and have a pretty low resistance of 120 ohms, so for a 450 V source you are roughly looking at around 3.75 Amps (most bulbs are rated around 0.5 amps). So not a great solution for high voltages. Some places sell high voltage discharge sticks for about twenty bucks if you want a profesional solution. But if you can find a high watt (2 W or greater with a resistance of around 100 kohms, that should work, just may take a while to discharge depending on your capacitors)
@@HTMWorkshop ah ok ima look for that tool I dont care about price and I work with these capacitors enought to warrent the purchase of a professional tool
@MyMate Leyto35 Thanks!
My trick for those 200V or 400V capacitors is to use a lightbulb with wires soldered to it and just discharge it using the bulb, best to use an old fashion one with wire inside it, really useful when you are dealing with such voltage.
Good visual indicator - although I prefer to use a couple lightbulbs in series for something as high as 400 V.
For as long as I can remember, my dad keeps a lightbulb on some wires in his tools, which he uses to test circuit completion when doing house electrical work. Of course he first finds the live phase with a tester, and then checks with the lightbulb to be sure the ground is also connected.
Why not use a voltmeter you say? Well he says, "I don't have a third hand to hold it with".
@S Wong it can but only for low current situations! Most LED's can take around 20mA so you do not want to exceed the max current (or else your LED will turn into a fuse - which is not the end of the world since most LED's are cheap but it may fool you into thinking your capacitor is discharged when in reality you just fried the LED).
@@HTMWorkshop this was a very in-depth explanation. Thank you!
Just curious doesn't the filament have to heat up first before it offers resistance? Do use a 400 watt bulb?
I came to send this video to my neighbor. I once saw a dog lick a charged capacitor by mistake while a parent was getting tools to repair an opened microwave. The dog was flung off and hurt pretty bad. It stuck with me. I was walking by this morning when I saw a guy taking a microwave apart. I asked if he discharged the capacitor first. When he said the what now? I told his wife please get him away from it. He will get hurt! I then sent them your video. DAMN People! Come on!
Great video! I wish they explained things this well when I was in school. They probably did I just didn't get it at the time. Age is not always a bad thing! Thanks for the info.
Great comment, so true.
they cover it indirectly if that is of any constellation. For my CompTIA A+ they said that if you get trained to work on televisions you will be taught how to properly discharge the capacitors, then in electrical they explained the relationship between resistors, capacitors, and time. Then throughout electrical they regularly explain that oftentimes steps often considered not recommended are the safest way to do tasks while implying that shorting a connection is sometimes the case.
Never once do they explicitly teach anything about properly discharging a capacitor but by the end you have tons of hints. So for this reason I am very happy to learn the specific recommended process for the first time and as such I would very much like to thank the video author.
I really learned a lot from this video and I sincerely thank you.
I hope you make a video teaching how to safely discharge a higher voltage capacitor-not necessarily the 2100V type, but the 200V to 400V range might be helpful.
For reference regarding the 2K capacitors, it may add perspective for people to realize that the electric chairs used in the electrocution of condemned prisoners typically delivered around 2,000V. Granted, they were higher amperage (7 to 10A) and the charge was delivered for several seconds, but it gives us an idea of the seriousness of 2,000V.
Yeah 2000V is high - yes 200 and 400 V are often used to start motors and fans (things that need high torque). Good idea.
That’s is fuccking painful for 2000 V and 1-10 A. Holyshitttt.
I'll never go anywhere near the insides of my guitar amp, and now I know why, instructive video, thanks
Apart from changing a tube, I'll leave it to someone competent. I'm too forgetful to mess with the innards of an amp and would die probably
Always cut the trailing ends of strings off when you change them was good advice I was given. 1: So you don't blind someone and 2) They can penetrate electrical equipment!
I remember fixing tvs and vcrs It's good to have the knowledge
I've been dealing with caps for decades, so I didn't learn anything new from the video, but I was highly impressed with your teaching style, calm and steady and looked like you prepared well. It is obviously aimed towards beginners, and you reduced the topic to its essential elements, and explained them simply. I was hoping to see what you had to say about BIG caps, I worked at a 500 Kilowatt shortwave station. Can't say "my loss" as I enjoyed watching your video. 73deK1WXY
Are there any other components you should be carefull with?
Anything involving high voltage.
Current transformers...If the secondary has no load, the secondary voltage can soar to very high voltages. Won''t explain why here, google it.
Large batteries...Watch your jewelry. If metal watch band or bracelet shorts out a large amperage battery, you will not be electrocuted, but may get an impression of the jewelry BURNED INTO YOUR WRIST. Can and has happened to people reaching up under the dashboard fiddling with stuff up under there. A ring contacting the battery terminal on the rear of the starter switch melted a friend's wedding ring into his finger, ouch.
Any one else got any suggestions?
@@robertstessel8780 Thanks for the great answer! Will keep this in mind.
Very good video and explanation, i once thought about touching one of capacitors even though it was only 25v and at that time i didnt know what those things were and well i have to say thank god i didnt touch them and thank god it wasnt a high voltage capacitor (didnt know what was going through my mind at that time xd)
Excellent explanation. Likely saved me from getting hurt today.
Good to hear!
Thank for the knowledge sir I really appreciate it.
One of my relatives son telling about his experience about electronics and then he told us about capacitor thing and tell us how dangerous it can be that's why I am here to gain knowledge.
Thanks, very well explained. I’m gonna be much more cautious taking electrical/electronic stuff apart going forward.
I have three microwave capacitors rated at 2100V sitting around my house not yet discharged! Just realized I'm lucky to be alive, and that is why I am watching this video.
RUclips can save you. Thank god I watched that video about what grenades do.
Usually, they have resistors built in to discharge themselves. But, it's always a bad idea to rely on one point of failure with big caps. Capacitors can also spontaneously develop a charge to do dielectric re-absorption. I personally like to keep them permanently shorted out with alligator clips like that, just in case!
@@HTMWorkshop - Excellent explenations for capacitors. I didn't know that they could charge on their own. Thanks
@@HTMWorkshop l
How did we get here
I use solder wick to discharge or verify discharge if not in circuit. I have a 8 Ohm 10 W resistor (used for ESU testing) I use for board discharges (with jumper wires of course)
🤔Interesting. I have not used solder wick for that application, but I see n no reason not to as long as you are ok with a quick discharge. Nice tip if your doing board work and some handy. The 8 ohm resistor would definitely be a good discharge resistor. Out of curiosity what test are you doing on the ESU with the resistor?
@@HTMWorkshop Covidien FT10, Force triad etc need to detect a patient load in order to energize
Thanks for this video demotration, really a life saver for people like me who has zero knowledge in electronics.
Glad it helped!
fantastic video sir. I wish I had an electronics teacher like this in high school.
I have read through some of the comments. I have worked around 400 volt lines and higher as a research scientist.
Around 400 volts, there is an invisible charge cloud or corona about these lines and devices connected to them. If one is grounded, burns, neurological and brain damage and death can result without direct contact. An kindly older electrician told me this when I was 24 or 25. He saved me injury and death many times over.
Good point - yeah I use to work with 1-10kV and your right (everything even air becomes a conductor at some point and ions can form). I use to do some electrospinning back in the day, and it takes advantage of that very effect.
Useful video 👍. Can i use a 20M ohm potentiometer to discharge it?
Thanks - depends on what type of power the potentiometer can take. The resistance is good - but if you run to much current (at a high voltage.. remember Power = current x voltage) then you may burn up the potentiometer. I would not recommend it for discharging very very high voltage things - but my guess is for most applications it would be just fine since it is just a high resistance - and therefore low current.
Thanks for this this informative video! I need to remove a very old high power xenon lamp igniter and want to do so safely and not get knocked on my butt!
Hope it goes well!
You are a great teacher! The video was great to watch. Thank you.
Thanks for the video. I’m looking for an example that explains what size resistor is needed, or should be used with, the capacity trying to be discharged?
Hmm - I don't exactly have a video on that. I do have a blog that may be helpful here htm-workshop.com/how-to-discharge-capacitors-safely/. Also I know in a couple of the comments for this video I explained some specific resistor choices for caps. The key is understanding the power the resistor can take and how fast you want to discharge the cap. P = IV or V2/R , so don't exceed the power rating of your resistor or you will fry it - also the time it takes is based of the time constact for a capacitive resistor circuit ruclips.net/video/JcrlL8YN6VQ/видео.html. A 10W 1MOhm resistor may be a good place to start but it is very conservative (for most circuits)
You made this so easy to understand. Great channel
thanks!
after getting taserd by that 400v in my laptop ac adapter while trying to repair it via replacement.. I'm here to learn to discharge that thing
Yikes! hope the video helped! Stay safe.
Also, as a note, that resistor is 5 watts which means it can take higher power. (Little resistors are 1/4 W or even 1/8 W. Not sure what surface mounted ones are rated at.)
Great video, thank you for taking the time to make it!
Haha hey, you have the same oscilloscope and multimeter as me lol. Always nice to see another Tack Life user out there. In my opinion they make pretty great equipment for the low cost they charge.
Excellent video! Very underrated! well explained! Thank you very much sir 😄
Thank you!
Thanks for sharing im almost have a heart attack when i saw the spark when you discharge the capacitor 🤣🤣
Hello, great video. A question: is it enough to have any resistor to discharge any capacitor ? I mean, can I have only one size so I can use it with a small capacitor or with a large one ?
resistance too high and it won't discharge. resistance too low and it will melt or catch fire. it matters, you can't just use any. it will depend on both the voltage and the capacitance of that specific capacitor.
nice educational video thanks . the microwave capacitor: could that start someone's heart if there wasn't a set of paddles near by?
Theoretically yes if pacing is not needed (there are some arrhythmia that require shock to be delivered at a specific time). That does not mean it's a good idea - since in practice you would want to size the capacitor correct, make sure there is appropriate contact with the skin (so as not to burn the body), make sure you did not discharge to much power into the power. It is possible but not advisable. Also there are different waveforms that are better than others for starting the heart - but a single capacitor can not control that. So in theory yes - in practice no.
Nice so not a great idea to do this but good information for the zombie apocalypse lmao ....
@@MF-sy7zq That is probably the perfect way to say it... haha
my friend was killed by a microwave capacitor
@@davidvankeuren6575 My wife and I had been discussing repairing our microwave oven as a DIY project on an old GE Spacemaker 1400 microwave. After reading about multiple instances of fatal microwave repair projects; we've decided that it will be safer to take it to an appliance repair shop.
I am sorry to hear about what happened to your friend.
This was some great presentation of information thank you. I am not strong in electronics but I am studying up to disassemble a digital camera that has a flash, and the manual states to discharge before taking of a certain part at these points. However it does not state which items I'd need. From my understanding are these ceramic resistors so big that I can order the same one I see you use or another video that I should be okay to use it for most "safe" capacitors, or do I have to do some math to match a capacitor every time?
I guess my question is more of an is it "a rule of thumb" question, as I'd assume its always safe to calculate what you're working with.
Good question - I don't have a good rule of thumb for which resistor to select - if you select one that is to high it may take forever to discharge and if select one that is to low your going to pull too much wattage (and fry your resistor or worse). I recommend calculating the power and the time constant if your going to discharge things yourself for high large voltage large farad caps. But if the voltage is below 24 (or even 100 V) in most cases your not in trouble and if the capacitance is in nF or uF that is pretty low so it will discharge pretty fast. I don't work around a lot of equipment I am willing to do general rules (to expensive to replace) but if the equipment is not to expensive I would use a 1 Mohm high wattage (20 W resistor) or something like this amzn.to/3yIYoRx. Hold that on the leads to discharge for a little while, then check it with a multimeter to see how much voltage has dropped, if its going to slow get a lower resistance and try again. Hope that helps a bit.
Coldn't actually see the resistor discharge technique but I got the gist, thanks!
Thanks! What res is recommended and up to what voltage cap? And is it alright to touch the leads of that res when doing that? Also is a discharge pen recommended for higher voltage?
That depends a lot on the situation - for instance do you just want to discharge the capacitor or do you care about keeping the circuit integrity and capacitor working afterwards. A very consdervative basline is around 24 V - I don't mind touching 24 V shorted but if you discharge a 24V cap fast it may damage the circuit around it (depends on the situation). In practically I wouldn't mind discharging a 500 V capacitor if it had a small capacitance and a insulated handle - but that is getting more risky and could easily damage the circuit. It really has to do with your risk tolerance and what your comfortable with but always best o err on the side of safety if you don't have a good grasp on the circuit and your own risk.
One thing you forgot to discuss, is dielectric absorption. It can cause capacitors that have been discharged to regain some charge after some time, amd could lead to a nasty surprise.
Do the microwave capacitors tell you how long it takes to bleed out that voltage once they are unplugged? I'm guessing a few seconds. Still makes me nervous.
I don’t think the manual will tell you...but your probably right. Assuming all is working correctly. Best to unplug, check with a voltmeter then do a quick discharge to be extra safe.
@@HTMWorkshop microwaves capacitors are around 2kv - 4kv , what size/type resistor would be needed to safety discharge the capacitor?
@@raybradshaw8444 It would depend on what kind of wattage the resistors could take. Maybe a 1 MOhm resistor ... but it could take some time to discharge depending on how many farads. Often you see 100 kOhms used in high voltage discharge sticks.
@@HTMWorkshop as a basic sum it took 15sec with a 50kohm (3 R in a sting) tool on 300v, and 30sec with a 100kohm (6 resistors in a sting) on 300v, so dum math says 300secounds with the 100kohm so 5mins for 3000v.
i just dont know if my little 100kOhm Tool will handle 3kv and not melt like a icepop, lol
@@raybradshaw8444 It just depends on what the resistor is rated for power wise - is it a high Watt resistor? The higher the resistors the slower the current will move so you can use lower watt resistors (its a tradeoff between power the resistor can handle and time it takes t discharge). You have to check both.
I never discharged a capacitor by shorting it with a screwdriver. Instead, I used a 40W incandescent lamp with a bare wire. I connected this lamp to the capacitor terminal during which it will light up briefly and then fades
This what i'm thinking. Thank you.
Please make video on how to safely discharge the high voltage caps thanks
I was thinking that, useful vid but doesn't quite deliver as promised in the title!
Great video, would have liked to see how to test the charge. I know you can use a multimeter, but they are very sophisticated alien-like devices. I don't know what setting(s) are proper for what scenarios.
Thanks - by charge were you interested in measuring voltage or capacitance? You can check out this multimeter video on our channel if you want ruclips.net/video/BxVbLKd5Kk4/видео.html
@@HTMWorkshop I'm just concerned about residual electric during electronics repair thru simple replacing of parts. For example, people say computer power supply units can have a deadly charge in them for a long time. How can you really know without testing them? I assume that's the only other major thing to look out for, aside from making sure the device is unplugged of course. Thanks for the link.
@@lakecityransom I have worked on quite a few computers - I have not seen to many capacitors dangerous enough to pose an issue. I have often heard that if you disconnect the power then hold the hard reset for about 10 seconds you can discharge any remaining charge in the supply - but I would be surprised if that was even necessary. I would be more worried about damaging computer components through ESD than getting shocked by a computer that is unplugged - most everything in a computer runs on low voltage - except the power supply. I mean it's possible you have some sort of super cooled computer with crazy fans and motors that are not normally included but most parts are low voltage. If your just changing boards or ram you really don't have to worry about getting shocked (just unplug the power cord since the line voltage is the only real thing to worry about). Now I am assuming your not dealing with a CRT screen computer - if you have a computer that old then yes you do need to worry about a high voltage capacitor (but only for the CRT screen).
@@HTMWorkshop Oh for sure I've worked with computers a lot. I actually mean working within the PSU unit itself. There are cases of teenagers dying if you Google on that. The most common reason to open one up is the PSU fan's bearing goes bad and starts making a lot of rattle. Its simply a matter of replacing it with another standard 80mm or 120mm case fan. However, you do have to open it up and all the parts are in there tightly so it is concerning to attempt unhooking one and putting the other one in.
I replaced a water intake control on a washing machine the other week and was questioning once again how safe I was being without testing components for residual electricity, but I did get the job done lol...
@@lakecityransom
Yes it is possible - many psu utilize capactive reactance to step down mains - I believe those are suppose to be designed with a bleed capacitor - but I am not sure. You should be ok to replace the fan - just be careful around any caps that read over 20 V. I would imagine the fan should only have a couple connections or more likely a single molex connector. Which should be safe to unhook and change out. If you want to be extra safe you just make sure to take your meter and put it into voltage mode - then measure across the capacitor legs - and make sure the voltage is low. Always good to take of jewelry and use one hand as much as possible to reduce risks but I would imagine its fairly safe unless your really messing around near the caps (and even those should discharge pretty quick if the circuit is setup correctly).
Thats why i click on this video to safely discharge hig voltages ones!
Just curious does that open part at the top also conduct electricity?
Awsome video although I like to have the same setup you have transformer and rectifier can you posted the design setup so I can do the same on my little lab. appreciated... thank you;.
to be honest I am not sure - wish I could be more help. you should be able to use any DC supply and high voltage transformer for the type of walk through shown - but if you needed to worry about power/current of the device that may get tricky to make sure you down draw to much power.
Does a 400v capacitor need to have 400 volt source to charge it fully?
Yes in general, if you had multiple sources for example you could use 200 V sources you could put them in series to create a 400 V source - but your still ultimately using a 400 V source
Excellent! Many thanks for explaining this so clearly.
super useful video. Awesome addition while studying theory
Thanks!
Thanks for the education sir. I appreciate the video. I think I'll leave capacitors alone.
Ha - well maybe just stick to low voltage caps - they can be a lot of fun!
Very informative and well done. Ur a nice talker, gj good video :)
Great job but my question is that how can I change the capacitor after discharge please 🙏 sir
iit is not because the max voltage supported by the capacity is 400V that you will charge it at 400V, this is the max allowed DC + AC ripple voltage supported by the cap.
You are correct that the listed voltage is the max recommended voltage (any higher risks dialectic breakdown breakdown and could damage the cap)
How do you determine which resistor to use to discharge which capacitor?
Good question, depends on how how fast you need to discharge the capacitor. Time constant is a key factor to determine how long it will take, time constant = RC. So if you had a 1 uF capacitor and a 1 MOhm resistor it would take 1000 seconds. You can always use a lower resistance value but then you have to make sure you resistor wattage is not exceeded. P = IV or Vsquared/R. So if you have a 1000 kV capacitor and a 1 kOhm resistor you would be dealing with 1000 W! if you used a 1 MOhm resistor you would be dealing with 1 W. High resistance value are safer in a sense but you have to make sure you wait long enough. Hope that helps
@@HTMWorkshop Thank you, but i'm still a little confused. What unit represent Time constant (second?), R (kOhm or Ohm), C (uF or F), V (kV or V), and what is I?
Let say i need to discharge a 400V 60uF capacitor in 60 seconds, i'll need a 0.4W 1kOhm resistor?
I can't seem to work out the formula, can you help me with that? Thank you very...very much.
@@mrdzin1209 Time constant is in seconds - you have to make sure R and C are in the base unit (ohms and farads). I is current. You will discharge that capacitor much faster than 60 seconds with that setup but you will need a 160 W resistor (I am doing those calculation pretty quick but I believe that is correct). You probably are not taking into account the unit prefixes for the first part. For the power calculation you need to make sure you square the voltage and then divide by resistance
@@HTMWorkshop Thank you, it's very helpful. And you're right about my setup, it would need a 160w resistor and discharge in 0.36 seconds (so a 16w 10kOhm resistor in 3.6s would be much more efficient). I believe you do that calculation in your head and that's freaking amazing.
Sounds like you got it, always a good idea to check with a voltmeter after discharging to verify. Or if that is not an option use a screwdriver to discharge any remaining charge (better to have a damaged board than a damaged hand)
When you discharged the capacitor with the resistor, did you touch both metal wires of the resistor
with both metal parts of the capacitor?
correct (botht he anode and the cathode of the cap)
@@HTMWorkshop Thank you! If the wires of 1 resistor are not long enough, could I use 1 wire from 2 different resistors to discharge the capacitor still?
@@grooty6434 Im not exactly sure what you mean - you can use two resistors in series - yes. There must be a path between the leads of the capacitor - what you put in between determines how fast the discharge (based off resistance mainly) - see more info on time constant of caps for how long it will take
You know you're about to see some crazy stuff when the letters "DO NOT TRY THIS AT HOME" are on the screen. :)
Great video, professor 👍
You look like a master. Can you just point me in the right direction? I have a Mark Levinson no.27 amp. When I turn it on I heard a strong pop on the right speaker and then the unit went into protection mode. Even time I turn it on after that the power switch would pop back to off. Same result with all cables off with only power plugged in. The power light still lights, fuse is good. Can anyone give me some guidance? Thanks
Not sure on that one - sounds like some sort of current issue. Honestly, I would be looking in the user manual to see the reason for protection mode - start narrowing them down one by one to see if any of the suggested corrections work. My guess is you may have already tried that but can't say I'm familiar with that amp.
Wanted to ask a question in regards to discharging using a ceramic resistor like you did in this video, I noticed when you were discharging you still had part of your finger on the metal bit of the resistor, Is that safe to do so?, Also does it matter what polarity the resistor is to the capacitor?, I'm assuming it doesn't have polarity and doesn't matter which way you discharge it, whether its face down or face up. Lastly do both the legs of the resistor have to make contact with the legs of the capacitor at the same time for discharging?
TIA
Resistors do not have polarity and yes both legs of the resistor must touch both legs of the capacitor to discharge. As far as if its safe to have your finger touch the metal part - the answer is maybe but best practice is NOT to touch it. Certain voltages are perfectly safe but if you are not that familiar with safe voltage I would just stay on the safe side.
why not use resistor to discharge capacitor that has high voltage if you are holding the ceramic part?
what would you suggest to use to discharge over 1,000 volt capacitor when usually equipment insulated for just 1,000?
thanks
You definitely can use a resistor but you need to make sure you get one with an appropriate wattage rating. You can reduce the power with a higher ohm resistor but then the higher the resistance the slower the discharge. I would use one of those high voltage discharge sticks I have in the description otherwise you can size out the resistor you need if you have a bunch of high wattage one - but for most people they don't want to bother with doing the calculation
PS: Up to what voltage is the screwdriver method safe?
Really educational video, thanks!
Do you have to touch both leads / connections of the capacitor? And the shock happening in what is between the leads? Or is it a matter of charge being able to go to ground? In which case, is only one of the leads actually dangerous (the one with electrons at it's disposal to send out)?
Usually, yes between leads. Touch current is going to be negligent unless one of the leads of the capacitor is already grounded (in which case if you touch the other lead it can still discharge). In other words caps are not by nature grounded but if you connect one lead to ground then the other lead is going to be dangerous (if its at high voltages)
What about using gloves to prevent shocks/electrocution? Like those that linemen wear for their work.
These gloves might be too cumbersome to wear all the time but I imagine they could be useful to have when in doubt
Yes you definitely could - but you can still damage the electronics if you are discharging the cap near the board. So that only works well if you either don't care about the device or if you have already removed the cap.
I am replacing the two capacitors on my subwoofer amp. Both are 80V 6800uf. Can I use the screwdriver method to discharge them?
Yeah you should be fine, may spark a bit but your safe enough
I have an old shortwave diathermy machine (Mettler 300) that seems to be malfunctioning, tubes seem to get hot (tubes have been changed as I first guess) but the coil doesn't seem to be hot. Under the lid are 2 separate capacitors (each set has 5 separate 28pf 5kv in joined parallel -- for 140pf 5kv each). I suspect these capacitors failed. To the look everything else seems okay and to the eye some capacitors appear to have cracks in them. These capacitors (10 in total) are ceramic disc capacitors. Warnings on the inside of the equipment to not work on it. No videos/aricles anywhere on how to discharge these. Machine has been unplugged for months.
Could be the issue, very high voltage. Yeah a lot of manufacturers say not to work on their equipment - this is more of a legal issue that a technical issue. The OEM is trying to protect themselves legally more than anything. I am sure they would tell you only a certified person should work on their equipment and tell you that it costs thousands of dollars to take the training. The capacitors are probably are not charged up, but better safe than sorry. I would use a high voltage discharge stick to see, ideally with an indicator LED. Then you can use your meter to confirm no voltage and try the repairs. But of course the OEM warranties and such will all be invalid but I am guessing that is already the case. I don't know who you work for but obviously they would need to be comfortable with the repairs and risks of repair.
Excellent tutorial, thank you.
Glad it was helpful!
Best video on the subject, very informative, thanks.
Thank you!
very informative, thank you
Excellent video, thank you for the knowledge!
Thank you!
Thank you!
Thank you for your content. This video was very helpful
👍
Thanks. Great explanations!!
Outstanding video, thank you very much.
You kinda made me feel at ease saying "it wouldn't be a serious shock" but I know I should still be cautious. I came from a microwave video and that thing is 2100V.
Nice video man!
Thanks for this video, very helpful
Great video
So I have 4 Caps that are in the power supply circuit of a stereo processor. It's 19.5V AC feeding 35V 470uf Caps. I need to replace them as a few have begun to leak. Do I need to worry about discharging them before un-soldering them from the circuit?
20 V is pretty safe, 35 V is still pretty safe but on the edge of possible issues. I personally would not worry but if you want to be extra safe I would just use a screwdriver to discharge them (or some other piece of metal)
Sir , i have accidentally shorted a 70 mf , 400 V capacitor with a screw driver. my question is will it fully damage my capacitor?
Not sure - depends on who made it and how well it holds up to the stress of the discharge. You can always charge it back up and see if it holds a charge. Very well could still be good - do you see any visible damage? What are you using it for?
My only accident when I opened a throwaway film camera with flash. I wanted to see what it was like inside and I shorted the cap. That was interesting.
Yes, I remember a day when it was in vogue for people to take off the cases of those and then charge up the caps to see if they could shock people.
Bruh that happened to me yesterday, why I’m here watching this
Same happened to me, disassembled one to play around with the flash with my brother and I guess I shorted a capacitor, because I got quite an interesting shock in my arm
Ditto
Great video. I now realize that I may have gotten very lucky by not killing myself with the microwave capacitor I have been handling. I'll be much more cautious with those in the future.
Stay safe!
Update: I also realized that I smashed the hell out of the Bryllium ceramic surrounding the microwave magnatron. I didn't die immediately from Berylliosis, but I probably took 30 years off my life. Happy scrapping folks!
Thank you for your video man appreciate it
Thanks!
This helped me so much thanks my guy
Your welcome!
Can’t you just wait a certain amount of time and they’ll discharge? I’m going to recap a Nikko amp and it will be unplugged for at least a week. Can the big caps hold a charge that long?
In most cases that can work but in some cases the cap may be very big and the discharge may take a while. In some systems there is not a bleed resistor to help discharge the cap when the device is off (depends on the device and application)
If you disconnect an amplifier (ie: 500w ClassD stereo and/or subwoofer amp with toroidal) approx. how long till all the capacitors discharge to a safe condition all on their own?
It depends on how big the capacitor and how big the bleed resistor is... best thing to do is measure it with your multimeter in voltage mode to see if there is any charge left
what about 50v 6800uf capacitor? got 2 of those and 4 25v 1000uf capacitors in an amplifier board that i wanna take apart. it hasn't been plugged in for months
Well I would think the capacitors probably fairly safe (but that is a guess I don't know what your board looks like) - I would just check them with a voltmeter. If they read 0 volts then you know they are already discharged. If not, use a high ohm resistor to slowly discharge them to protect the electronics. My guess is they are already discharged.
How long can they hold charge for ?
Well, I assume you mean in an off state (meaning not used to power anything), in that case it depends on the amount of leakage current. So if you had 1 Farad of capacitance fully charged you could figure out the time constant using t = Resistance * Capacitance. So you would need to know the effective resistance for the leakage circuit. Then multiply the time constant by 5 to get the effective discharge time...or you could just charge it up... then measure the voltage over time and see when it starts to drop (more of trial and error type method). Here is a general video on the time constant if your interested ruclips.net/video/JcrlL8YN6VQ/видео.html
@@HTMWorkshop oh man appreciate it
@@HTMWorkshop just out a volt meter to it nada
@@HTMWorkshop it’s an Xbox brick power supply I had to ask first ! 2 in there are 200v 450f and 4x 16v capacitors as well ! Did not know if over time or if I needed a resistor to drain them but it did over time apparently
I have a physically large resistor. It is 220 ohms and 25 watts. What would the pros and cons of using this on a 450 volt capacitor be?
Well if you calculate the power at 450V and 220 ohms I get 920 W - so your going to exceed your resistor power capacity - choose I higher ohm resistor to reduce the W
V = I * R --> I = V / R
P = I * V --> P = V^2 / R
P = 450^2 / 220 = 920 W
R = V^2 / P
R = 450^2/25 = 8100 ohm
So, you need at least 8100 ohms to safely discharge that capacitor. Just get yourself a 10,000 ohm resistor and that should do it.
Whoa hey you need to amend this video full stop. To whoever ends up on this video looking to discharge a capacitor, DO NOT EVER TOUCH THE LEADS WITH YOUR BARE HANDS--- NO MATTER WHAT THE SIZE. Never, never ever ever holy shit. Ok let me clear somethings up here for those who happen to watch this and notice this comment:
1- A volt wont kill you. Voltage is best explained along with amperage when trying to be practical about it. This explanation isn't accurate from a scientific standpoint per se, and I wont go into the science here, but for the sake of what happens to you when you're electrocuted, I think this works great and it's practical:
An amp is the actual electricity. Imagine a marble, that's our amp. If the marble is on the ground, holding still, we're at zero volts. That marble won't move. Now I lift the marble and drop it. Instead of thinking of how high and comparing that to voltage, instead think of the voltage as "how hard" that marble hit's the ground when I drop it. So, 10v wont hit very hard, but 120v or 240v can hit you hard enough to blow you off a ladder. But, that "how hard" part can't kill you without the amperage(marbles), which is what's actually dangerous. If that marble is on the ground at zero volts and I were able to somehow reach down and grab it, I'm gonna get messed up.
1.a- 1 thousand amps at .001v will kill you dead- full stop. Like a steam roller moving slowly and, if you can conceive it, softly over your body. I mean it's not really slow or soft obviously, this shit moves at the speed of light in reality. But you get the idea here I hope. You're still 100% dead. But .000000001 amps at 1 Million volts probably won't do terribly much to ya in the end. That's like just one of the tires off of a micro machine toy hurled at you really super hard and fast. Probably very few scenarios where that kills you outright yea? Though, and this is important, don't take that for granted either because the electrical system that keeps your body functioning isn't insulated. We're made mostly out of water and we've all got a pretty good salt content so our bodies are pretty great conductors. And our super exposed electrical system that keeps us ticking doesn't like disturbances. Like....at all.
Amperage is why I suppose I don't need to list anything else to explain why you don't mess about with capacitors if you're not 100% certain what you're doing. That loaded spring allegory that he used was kinda on the money, but that spring is amps. A capacitor discharges amperage. The voltage on a capacitor is irrelevant when considering how dangerous it is. They're all dangerous. A 10v capacitor has enough amperage to disrupt the sinus rhythm of your heart without you feeling it or noticing it. You can put yourself in A-fib without noticing it until it's too late. You can compare you're heart to a blower fan on a furnace. Our sinus rhythms(the full process behind each heart beat) are like the balance that is in place on those fans. If those fans end up off balance, the motor will eventually trash itself. Same goes with your heart. If you disrupt your sinus rhythm, your heart will start to break down and it will eventually fail prematurely unless it's caught during a physical. In which case, depending on how long you were in A-fib, your heart may be so badly damaged that you require extensive medical treatment ranging from ablation (where they have to open you up and make little cuts on your heart and then try to shock it back into rhythm), to a pacemaker and if you think your insurance is going to make that process easy for you.... well... that should go without saying, no? Also, the average survival rate after that point is about 5 years. And, speaking from what I've personally witnessed, you can walk around for a good 10 years being in A-fib without being aware of it or even having a doctor noticing it/catching it and that's about all you need to completely trash your heart.
So don't touch capacitors with your god damn fingers. Don't do it. You don't need to feel the shock for it to kill you. I can tell this poster is pretty experienced and definitely very knowledgable , but man I wish they were just a little bit more concerned about the potential for life altering mistakes/death involved here. And, honestly, if I were you OP I'd go get an ECG asap if you've been touching these lower capacitance capacitors on the regular. All it takes is 1 shock to throw you out of rhythm just a little bit. And that little bit has a snowballing effect in the end. And, again, you don't need to be able to feel it.
Also, don't discharge anything over 50v with a screw driver. They make capacitor discharge pens that are tailored for different size capacitors. Those are a pretty safe bet. Another option is to simply disconnect the capacitor and leave it be for a while. You'd have to look up the time needed for the size you've got, but eventually it should discharge on it's own. However, the only way to tell when it's done discharging is to either test with a voltmeter or a discharge pen.
Hope I didn't come off so abrasive here that my points were lost, but OP, for really reals man, I'd go see a cardiologist if I were you just to get checked up on. It's not a guarantee that you absolutely will throw off your hearts sinus rhythm with a shock, no matter what size, but it is very much a possibility no matter how small that shock is and that's all you need to properly fear these components. Honestly, it's the small shocks that you don't immediately go to the hospital for that are more dangerous than the big ones that knock you out. At least when you're knocked out and you wake up in the hospital, they've already made sure your heart's working normally. Bit that little nip from that low voltage system that you didn't even think about could be a ticking time bomb
Can you safely discharge a capacitor using this method while it's still connected to a board?
If by safe you mean for people, yes it is relatively safe for the the operator. However depending on the board electronics you want to be careful not to damage any part of the board. Make sure you understand the function of the capacitor before discharging to be safe for both the operator and the device.
Very helpful ❤️
who watched this after got shocked by a capacitor ? LOL
I was trying to fix my laptop charger, and got shocked and indeed the capacitors are responsible for that. I am gonna call 911
By "touching it" do you mean touching both terminals at the same time, or getting shocked by only touching 1 terminal. Can you be more specific? I have an Ampeg svt I am going to take to a tech but I need to educate myself and do it eventually.
You could potentially get shocked by only touching one terminal. It has to do with potential difference - so if you touched the terminal that is at a high voltage with respect to ground (aka the potential of where your touch feet or other path to low voltage if another part of your body is touching something). Current would travel from the touched terminal to the low voltage drain. This is one reason that people where high resistance rubber shoes or something of that nature to reduce the chance of large currents running through your body. It's also why line workers (or birds for that matter) can touch high voltage power lines and be safe (there is no easy, low resistance, path to ground). If you need to touch a lead on the capacitor the best thing would be to drain it first, then verify there is no potential difference with a voltmeter.
Nice vedio..
Is there a reason they don't put some kind of international hazard warning, like a skull and crossbones, or at least a stop sign, on all high output capacitors?
Well its hard to draw a line in the sand and say this one is hazardous and this one is not - depends on a lot of factors. Its a good idea though and I do see some high voltage stuff marked (not quite like that but definitely a hazard warning)
Great video. Thanks for the explanation.
The microwave capacitor shows 0.7 uF. I know the voltage is high (if charged high), but the capacity is low (?) even if the miniscule time period is enough to stop a heart. Please comment. Thx.
Doing a neon job for another Dept…Going back and forth from alley to inside
Yikes! Sometimes we all learn lessons the hard way
Excellent. Thanks.
Glad you liked it!
Is it good or ok to replace 2200uf 35v with 2200uf 16v?
well I would say in general no - but its going to depend a lot on what the 35v capacitor is used for.
@@HTMWorkshop power supply I will go for 2200uf 50v then. Don't have 35v.
@@NengVang2007 I think that has a better chance of working - goodluck!
What would happen if you discharge a large capacitor by inverting it and pressing it into a wet sponge?
Very informative
this explains why i received a shock when i disassembled a disposable camera when i was a kid
Ha - yes i remember that trick. That was a good way to experience electric shock.