Reforming Capacitors - Everything you wanted to know
ฝัง
- เผยแพร่เมื่อ 5 มิ.ย. 2024
- Here are some ways to help me make more videos!
Reference material:
- www.tdk-electronics.tdk.com/d...
- chemi-con.com/wp-content/uplo...
- www.hb9aik.ch/notes/MIL-HDBK-...
Chapter titles(thanks to Forgotten Machines!):
0:00 Intro
1:09 How Capacitors Work
2:28 Aluminum Electrolytic Capacitors
3:57 Capacitor Lifecycle
5:33 Old Capacitor decomposition & reformation
7:48 Analog vs Digital (regulated) equipment
8:55 Reforming Standards
9:31 Equipment Needed
10:31 Basic Setup
11:19 Demonstration
12:56 Better Gear & Software/Web Interface
15:28 Capacitors Off Limits (for now)
16:15 When you should & should NOT Reform
17:49 Conclusion
18:48 Credits
Buy some Merch:
Merch: tech-tangents.creator-spring....
Leave a one time tip:
Paypal one-time: paypal.me/AkBKukU
Ko-fi: ko-fi.com/techtangents
Amazon Wishlist for Production Gear:
www.amazon.com/hz/wishlist/ls...
Become a monthly supporter:
Patreon: / akbkuku
TH-cam Membership: / @techtangents
Paypal Monthly: techtangents.net/support/
Other Links
TH-cam: / akbkuku
Twitch: / techtangents
Github: github.com/AkBKukU
Thingiverse: www.thingiverse.com/AkBKukU
Discord: / discord - วิทยาศาสตร์และเทคโนโลยี
This is also an issue with grossly overrated capacitors: If you use for example a 50V capacitor on a 5V power rail, it will initially work as intended, but with the operating voltage being so low the capacitor can't properly reform the oxide layer and will lose its formation over time. It's always a good idea to leave some safety margin for the eventual stray voltage spike, but too high is bad as well.
Wouldn't it just slowly approach being a 5V capacitor then with the oxide layer rebuilding at a much lower rate? The large safety margin will be gone after a (long) time, but I can't see why it wouldn't continue to be operational at the lower-than-designated voltage. Maybe I'm missing something, though?
Likewise, for filter caps, using 10,000 mfd to replace a 10 mfd may not be a good idea even if it seems like more filtering is better. Larger value capacitors have more current inrush when initially powered which can damage other parts of a circuit. It's not usually a problem, but it some power supply circuits it can be a problem.
@@ResonantBytes Notice that the reforming curve is just that, a curve. Since it's not linear, it can be difficult to predict how using a higher voltage cap will function in the long run. Generally speaking, a lot of time and effort goes into the engineering of most electronic circuits and the engineers often choose specific values and types of components for reasons that may not be immediately apparent. But, it's always a safe bet to replace a component with one of the same material type and values.
@@projectartichoke a lot of time and effort? I give you the salt bae meme with capacitors being sprinkled. Capacitors are often specifie based on prior experience and just industry tradition, and if it hasn't caused issues in engineering samples, that's it then, that's what it's gonna be. If this wasn't quite the optimal choice, well what are the odds that the commercial/useful life of device will exceed 5 years? It's going to be fine.
@@projectartichoke Agreed, it's hard to predict what happens exactly inside a certain cap if it's not used in a way that was tested.
But that doesn't convince me that there will be more problems when using a capacitor with significantly lower voltage than it's designed (and tested) for. In analog circuits that happens all the time e.g., when using an electrolytic cap to block DC from an AC signal. There the maximum voltage might only ever be reached in certain conditions, even only in fault conditions, but still they aren't failing more often than caps connected to a power rail. I'd argue it's even the opposite. Those caps might fail due to other reasons, especially heat and high currents, but if those are the limiting factors, I doubt the original argument about the influence of higher spec caps even more.
Yes it's not linear. But it doesn't have to be. It's an equilibrium system. When the oxide layer degrades, current may be able to flow at the current voltage. If it does that will rebuild the oxide layer, reducing the current that can flow at that voltage until an equilibrium is reached where the oxide layer rebuilds as fast as it degrades (or other effects start to have an influence). The oxide layer will be weaker than if the cap had been powered near its designated limit, but any current due to degradation of the oxide layer would have contributed to the regeneration of it. Also presumably less electrolyte will have been used which would actually prolong the life of the capacitor.
In the Telecom Industry, we are running into this more frequently, as legacy equipment shows its age. Most of our older Voice Switches employee electrolytic capacitors, to add further filtering to our primary office battery of -48 to -53 volt DC. Over time, these filters caps develope leakage currents outside acceptable limits, & thus they are fused accordingly, to reduce catastrophic failures. As part of our testing, we precharge caps with a series light bulb, of a known value. When the light extinguishes, the cap is charged with minimal leakage. However, if the bulb remains illuminated, it's time to replace the cap. It's old-school, but is time tested, & relatively simple to do.
I like that idea. Thanks!
yeah, visual test rather than using testers, I like it
@@zer0b0t You need to do both.
And the electric company wants to come install a smart meter on my house, HA! jokes on them!
3:50 almond
I like how you reversed the footage of you taking a capacitor apart to show how it went together. That was smart!
Keep going until the caps are new again!
Now you're thinking 4-dimensionally, Marty!
@@nickwallette6201 An old cap will NEVER be "new" again. It may be usable, but that is different.
@@johncasteel1780 I don't have much of a sense of humor (just ask my wife), but even *I* could tell it was a joke.
@@alexplorer I guess he actually used a time machine for that video. Because he accidentally left the packaging in the shelf behind him.
This man found a way to turn hardened criminal capacitors into reformed members of the board, WITH ONE SIMPLE TRICK!
Lol
salvation lies within
"It's never too late to mend".
_WITH ONE SIMPLE TRICK_
MANUFACTURERS DON'T WANT YOU TO KNOW!
MAYBE.
The best part of this video for me is that now I understand the reason electrical equipment disconnected for a long time will bust when reconnected again. Thank you!!!
Yup. When weak capacitors are hit with full voltage they go poof and tend to take other components with them when they do.
@@1pcfred And many times, the other components are made of unobtainium. Power transformers come to mind.
@@johncasteel1780 I don't see a capacitor taking a transformer with it. Transformers are fairly rugged and usually fuse protected. But sensitive active components could be at risk. Even resistors often masquerade as fuses in circuits. When they go it is often impossible to read what value they were. They'll either burn up or completely vaporize.
I build and repair guitar amps, mostly tube amps with supply voltages that can many times reach over 500vdc. A very common practice is to use an incandescent light bulb in series with the power cord as a current limiter when powering up an amp for the first time. The light bulb will light up, then dim with current draw... a nice visual reference, like the needle on your analog multimeter. I was taught to bring the voltage up incrementally to "break in" or "form" the new caps... Now I know exactly what's happening!
a bulb limiter is a very good idea and i would consider it essential when first testing items of unknown state ...
I do the same with 70's and 80's high end Pioneer amps.
@@TomKappeln should ALWAYS test any old electonic equipment with some sort of self current limiting devce, NOT rely on a variac, they dont...
Having a background in electronics. This video is very very helpful. You did a heck of job. Well done sir.
Shelby, you have risen to a new level!!! I'm SO impressed by the technical information, backed by your research and experience here. And most valuable of all, you explain the science behind all of this...so I thank you for making this very professional-quality video and publishing it here for folks like me to learn from...thank you so much!!! Fantastic!!!
Yes. Very well done!
That web interface is pretty friggin slick!
For something like the Data general, you can definitely appreciate why reforming would be required. Also great explanation, thank you for sharing!
One of the best and comprehensive presentations I've seen.
This is the most comprehensive video about capacitor reforming I've seen. Thank you.
I really don’t understand any of this . But I loved this video. You are so well spoken, genuine , and easy to listen to. You are a amazing teacher and a great salesman. Keep up the good work. Your awesome man.
Are you his awesome man?
ikr?, I have basic knowledge about electronics but english is not my first language so I had to rewind several times to kinda understand some things, it was interesting and entertaining anyway.
That was quite an eye opener! Made me realise something about these old hard drive supplies... some of them take 3 spin ups to get going, amazing it works at all it won't die.
I've got years of analog electronic experience and never knew this was a thing. I'm still learning, cool!
Me too - although I knew that old caps dry out, leak, or explode (it happened to me ;0 ) and sometimes must be replaced even if the gear they're in has been in constant use. In the audio industry, mixing consoles are "recapped" after some time interval. However, some techs go too far and replace *all* of the mixer's electrolytic
caps which usually isn't necessary.
Really great video - great explanation. Seems consistent with my experience with it. Nice to have the video to share with others. Many thanks. Subscribed. Cheers
Ha I've got that same radio shack multimeter I've had since I was a kid in the 80's! Learned more about capacitors here than in all my years replacing them. Great work!
Incredibly helpful. Someone suggested that I reform some new power supply filter capacitors before I install them (they had been sitting more than two years) and I had no idea what he was talking about. After watching your video, I completely understood what I was doing and why I was doing it; was able to set up the circuit, and do the job safely and correctly for all four 33K ohm capacitors. Excellent and entertaining presentation, very clear and understandable. Thank you!
I'm so glad you made this video. I've also done a bunch of research on this but you've put it all together very nicely and made ti relevant for people who like restoring vintage computers. Well done - thanks!!!
Well done! We run into this at CHRS all the time. Reformed many; some are just too far gone. Thanks for spreading the knowledge!
It was really fun watching you work on this stuff live!
Fantastic info. Love the idea of using GPIB to automate. I have that same bench meter and a PSU with GPIB. I’ll be giving this a try in the future.
Used to repair welders and my boss showed me this neat thing where we put a run-out gauge on the side of a capacitor and tested the welder with our load bank. Watching the caps change diameters under use was interesting. It had no diagnostic value as far as i know but it was interesting in a " huh? Well would you look at that" kind of way.
I did hear about this about 55 years ago. Now I understand it. Well done!
I means you are really old
@@robsonrobbi1763 You are obviously from the 'I' generation.
Your observation of the obvious is amazing!
FYI: When I first became interested in electronics, there was no internet to find out anything. As a teenager, if I wanted to learn anything, I had to walk down the street, catch a bus to the city, walk to the library and hopefully there would be a book addressing the topic I was looking for, and if there was, I would have to read many chapters to find the thing I was looking for - no quick search feature or hyperlinks. 🙂
The idea of reforming old capacitors is cool and maintians the original look of the device. I would rather scrap them when you are working on expensive or antique ( vacuum tube ) equipment.
But I love how you go into the detail on how to do it.
It might be worth mentioning that for non-polar paper capacitors, reforming like this doesn't work, instead the paper dielectric has absorbed moisture and you need to get it out, for example putting the capacitor in molten beeswax above the boiling point of water... or putting it in an oil, and then pulling a vacuum on the capacitor that will boil off the water as well. I've done this and it works
He *did* mention that this is for one specifoc type of capacitor. I do hope he will do the rest as well.
Please just replace it. Paper caps like that will never be really good or safe again. They are at the end of their life or beyond. Want an original look, restuff them.
Yes, paper capacitors can be theoretically "repaired", by boiling them in hot wax for an hour. That drives the moisture out and rebuilds the insulation layer of the paper dielectric. But this works with larger unsealed ones, that were mostly from 1930s-40s. There are some videos of some people doing that, and the insulation properties increased from like 1M ohm to few G ohms
Completely sealed "molded" capacitors (Think of Sprague black body, yellow writing types,) (paper types) are all bad due to the paper inside becoming acidic, not just moisture. Wax body capacitors have both moisture and acidity problems, so you are just lowering one issue, but the other far worse issue still remains. Think of discolored pages in a an old book (yellowing or browning paper) this is whats going on inside all of the old paper caps. They all need replacement, no excuses, just physics and logic.
I usually carefully reflow capacitors at 110 Celsius (while they are rated for 120 Celsius). That's all I will ever do apart from replacing them.
Well researched videos about topics that no one else bothers with is exactly why I'm here.
I love this video, and good information to have as an Auto Tech in an ever expanding electronical field.
You sir, are a perfect, ideal, clear and concise tech speaker/writer! I am impressed and educated. Bravo # 1 !!!! Perfect speaking voice as well. Bravo #2 !!!
An intelligent video about reforming, not just DO or DON'T because that is how I do it. Thanks Shelby.
Hey, thanks for a nice and in-depth explanation! I've known about reforming capacitors ever since I started restoring tube gear, and I sometimes do that both in existing devices and new devices I build using antique components (can electrolytics etc.). Generally I test them before reform attempt. If there's no capacitance, it means that the lead has corroded internally and the capacitor is dead. Otherwise I'll attempt reforming, bringing the cap up on a 300VDC power supply through a current-limiting resistor, by setting the voltage to get ca. 5mA out of it, leave it for a few hours and bring it up again after the current drops below 0.5...1mA, observing the max rated voltage.
Looks like I could use a CC/CV high voltage supply for that and for tube circuit prototyping :)
So many people missing the point here. There are certain caps that you either can't buy anymore or that can be prohibitively expensive. If you can reform them, you can potentially save a device from becoming ewaste.
I reform capacitors purely for the Mr. Wizard voodoo aspect of it. Quite frankly I don't need any capacitors. As they are neither food, clothing nor are they shelter.
@@1pcfred I'd say you got the point on the most fundamental level, with an extra point for humor reforming.
You’re a good teacher! Thanks 🙏
An easier and more elegant method is to use a Adjustable Current Limit Supply. Dial in your max current, set the open circuit voltage about 15% to 20% below the rating of the Cap. After stabilization keep the current limit unchanged but raise the open circuit voltage to the rating of the electrolytic. BTW, you did a nice job describing the idiosyncrasies and reforming of Electrolytic's! It's been over 65 years since first studying them.
Wakodahatchee Chris
I was thinking the same thing. Why not use a constant current regulator/source with a maximum voltage topping out at the rating of the cap?
I just came here to make this comment. Cheers for doing it for me. A bench PSU with voltage and current limits has been standard for a couple of decades now. All 3 of my s/h bench supplies have it.
Reminds me of when I ran the process a few years ago, with decent results. Saved a bunch of money on some very large caps, with an 80% success rate. Ultimately other problems with that PSU led to retiring it and installing a modern switchmode option, but it was good practice.
2 things to note here:
1) the sinkrate of the current is also greatly depending on the capacity because it is high on discharged capacitors. When they charge, the current goes down.
2) why didn't you use the current limiting function of your psu? It nearly does the same but without bumps. You can even charge lithium ion batteries with such psus, just set maximum voltage and current.
It's called CCCV. (Constant current, constant voltage) or IU.
Came here to ask about #2 ... it seems like a constant-current of 2-5mA and a maximum voltage at the rated working voltage would work as well or better. Is there something important about the stairstep method?
Using a psu in CC mode was also my first thought.
I guess that with an analog psu with a single potentiometer current control, even if using an external meter which gave precise current readings, it might still be extremely tricky setting a very low current.
Rather easier if the psu had coarse/fine controls, but with a digital psu which had current control down to the mA level, it should be really easy, as long as the psu did what it was supposed to do at the extreme low end of its current limit range (I'd still probably put a meter in series to make sure).
Most PSU you find in use are normally reasonable in voltage control, but current control is normally very poor both in terms of loop stability (they oscillate around a set current nicely) and in actual control ability. you need a SMU, generally not a common, or cheap, item in a workshop, to get good repeatable and reliable current setting ability, or a constant adjustable current supply, also not common. So a constant voltage power supply, and a resistor is the thing to do, though with very large capacitors you can use an incandescent lamp, rated for roughly the voltage maximum for the capacitor (so a 120V lamp for a 100V capacitor, and a 230V one for up to 400V, with a 12V and 24V lamp for lower like 15V and 35V) to provide a faster charge current, yet still provide protection against it going suddenly short. Light bulbs around 15W for the higher voltage, and 5-10W for the lower voltages works. So long as the voltage is within 50% of the rated either way it will survive short term overloads, plus visual indication on the higher voltage ranges by it becoming a photoflood lamp.
@@SeanBZA It's been a while since I used a bench power supply with a variable current limit setting so maybe it is difficult to set the current correctly. I'm still curious though about the original question of would it work fine without the stair step? it's pretty simple to rig up precise(ish) constant current circuits with a couple of transistors and that would be easier for me than getting GPIB set up.
@@johnwilson839 Does not really need constant current, error versus simple RC will not be much of an issue, plus you can also use the drop across the resistor as a current sense.
While some PSU units are great with CC mode, I find a lot of the lower end ones are not exactly great there, especially with a very large capacitive load on them. After all a 5c resistor is cheap, and can act as olfactory warning of high current flow.
This is the definitive video on capacitor reformation. Thank you TT!
Thanks for covering everything from the basics - I suspect people from the "bad caps" days will imagine that "reforming" just means the same (euphemistic) "remanufacturing" or "refurbishing" and all the baggage that comes with that era.
The self-healing page at 4:49 is about metallised film capacitors. Entirely different from electrolytics.
I'm just starting out to learn about electronics/circuitry and most channels are hard to understand and keep up with but this is oddly very easy for me to understand. I would love to see more videos like this about basic components or ics, or different logic systems etc explained for noobs like me
Great video topic, and well explained. I first encountered the concept of electrolytic capacitor reforming in a manual for an industrial variable frequency drive (for speed control of AC motors, if you're not familiar). It was a totally foreign idea to me, and I was surprised to learn that it's necessary due to the way electrolytic capacitors work, as you described in the video. I had no idea at the time, and I still think it's pretty wild.
One thing I would like to see covered and examined is how many manufacturers cut corners and install capacitors in devices that are barely able to handle the rated voltage in their installations. A couple cases in point here that I ran into years ago...
I had purchased a plasma TV when they were all the rage. It worked fine for about a year and then I noticed longer and longer start-up times for it. Then one day I hear the dreaded high-pitched "pop" from inside and smell the all too familiar odor of the electrolyte. I set the TV aside and we bought a new LCD one. Everyone seems to understand the power demands of the plasma versus the LCD (and now LED) sets. However, I was not going to give up on the plasma. I had heard of them failing all across the country it seemed!! I was convinced of a simple explanation. Taking apart the plasma TV took longer with the about 800 screws (exaggerated of course) holding the case halves together, I found that it was neatly laid out with separate boards for the various functions, one of them being the power supply. As an aside, these power supplies have NOT radically changed and are still used in all sets! Looking at the board I clearly saw the popped open capacitors and others that were bulging. I looked at the rated voltage of them and quickly decided that the manufacturer had not allowed any leeway as they were right on the actual voltage applied to them. I took down all the ratings and then went to e-Bay and bought a whole new set of them at DOUBLE the rated voltage. Now, here's the most interesting part... The circuit board was actually set up to use larger capacitors than what were installed!!! This was plain to see by the pictorials drawn right on the board and the extra space around the originals. Nothing else on the board had extra space. The new capacitors arrived, and wouldn't you know they fit the actual available space perfectly. That plasma set worked fine afterward, and it is still working like a champ in my living room 20 YEARS later!!! I only wish I had started repairing plasma sets for other people as so many were thrown away for nothing more than $12 in caps and a little labor on my part.
My second great instance was the control board for my $1 Jacuzzi hot tub that failed (yes, it cost me $1 for an eight-person hot tub!!). It sort of mirrored the plasma TV in how it gradually failed. I took the board out and saw it looked almost perfect. A couple caps were peaked though but not ruptured. I found the test sequence on a web search and proceeded to measure everything until I could go no further. At that point I sent an e-mail to a person in AZ who could rebuild the boards. I gave him my thorough test results and he was so impressed that he called me! He said that it was going to be an easy fix since I knew my way around and that I wasn't going to believe what I had to replace. The capacitors were my first guess and was right. Again, I ordered double the existing voltage rating and oddly, there was extra space on the board again... Seeing the manufacturing pattern here? After replacement the hot tub was back in operation, and I was relaxing in it until we moved out of that house and sold it before that move. For $3K in case you're wondering!
So, the question remains as to why manufacturers are shortchanging the capacitors in everything. Are they simply doing it knowing that they will fail and the average person will run out and buy a replacement device? I smell a rat here....
This is the strategy of limited lifetime of device. So after guaranty is over, the device will fail and you must buy a new one... Not only capacitors but insufficient cooling on power transistors and ICs etc.
Very interesting. Thanks for the informative post. I would love to hear what Mr. Carlson would say to this video.
Lol he’d be giving a thumbs down, for sure. Not worth risking your equipment!
He'd tell him to at least make his capacitor tester, so he knows for sure if the caps will hold up.
I think he would be fine with reforming. He has made a very nice variac and dim bulb limiter for bringing up older tube equipment.
He did comment elsewhere that paper capacitors must be replaced. Not only do the “waxies” take on moisture but the paper becomes acidic. These capacitor types need to be replaced.
A clear and concise explanation. Keep them coming.
Very interesting, good knowledge to have. Filled in some gaps of things I didn't understand. Thanks
This show puts you on my A list. I like how you use the use the junk i bought when i was a kid. God bless Radio Shack and the battery club. And remember Boys and Girls a new cap can have issues that will make you cry. Good luck to you all on reforming your cap world. Take it from me when you do this stuff wear the safety gear. Best Regards Jack.
i worked at a power supply manufacturer for about 30 years as a technician and then engineer. Our units supplied anything from 3v at thousands of amps to hundreds of volts at several amps. The older designes used computer grade caps with screw terminals and these became hard to source. I used to setup a group of caps with individual resistors in series with each cap. I'd start at about 25% of the rated voltage and check the srop across each resistor. After they settled forwn I'd increase the voltage to about half the rated voltage and do the same thing. Then I'd go up to 75% and let things settle for an hour or two. before going home for the day I'd go up to the full rated voltage overnight. After each voltage level I'd check the drop across each resistor and anything over 5-10 MA leakage was a failure (these were old can caps). Atfer the last full voltage run I'd put a red dot on the caps that passed.
This proved to be a good indicator of cap longevity but anything over 10-15years was very iffy, even if the caps were NOS. Old caps just are not as well sealed as new ones so they can dry out just sitting in a box. cCps in use can last a very long time because they are kept active, I've got tesxt equipment that is 60 years old with 500v electrolytucs that still work just fine because they see use (Heath 0-400v regulated power supply I built in HS).
I had some of these boxed new-old-stock low voltage/high capacitance devices that showed dead shorts when checked with a multimeter. I attempted reforming using a low-voltage supply and a series resistor, such that the forming current would be just a few milliamps. Unfortunately, these capacitors were truly shorted, so they resisted all attempts at being resuscitated.
@@klafong1 Reforming can revive tired caps but there comes a point where they are just not recoverable.
Great explanation of the reforming process!
I generally use my small HP bench supplies (6212A or 6216A) for caps rated up to 100V, or a 6515A for anything higher. All of them operate in either constant voltage (what people generally think of when working with a power supply) or constant current mode. For the 621Xs, short the output and turn up the voltage a bit, then adjust the current limit for somewhere between 5 and 20 mA. For the 6515A, this step isn’t necessary as its output is fixed at about 5 mA.
Once the current limit is set, remove the short and set the power supply to the cap's rated voltage. Turn the power supply off and connect the cap, then turn the supply on and it’ll increase the output voltage to maintain the current setting until it reaches the rated voltage, at which point it will change to CV mode as the leakage current decreases. Less babysitting needed that way, and if the cap doesn’t fairly quickly get up to the rated voltage, you know it’s toast. I monitor voltage and current like you do - voltmeter across the cap, and milliammeter in the low side between cap and power supply negative terminal.
I came upon a box of big caps I had squirreled away a few weeks back and have been reforming like a madman lately. Most have come back nicely; only a few went into the garbage. In my opinion, at least for larger caps, it’s definitely worth a shot before just blindly replacing them. Certainly those used in older high end test gear (HP, Tek, Fluke etc.) are normally very high quality components that will last a long time if properly cared for.
I agree that just using a bench supply in constant current mode with a correctly-chosen target voltage should be more straightforward. On one hand, I _love_ the scripting Tech Tangents did for this project; these kind of scenarios are why I always look for computer interfacing options when I shop for test equipment. But I don't see what stepped voltage increases can do for you when the power supply can regulate the current within a chosen target for you. For that matter, no need for a resistor either (it looks like resistors were mentioned in that specification for use with a constant-voltage-only supply). And no need for external voltage or current monitoring: typical bench supplies should give you a voltage and current readout, and at 2-5 mA you don't have to worry about voltage measurement errors due to drop in the leads. KISS.
One exception I can think of is if the power supply doesn't offer fine enough current control or current measurement. Cheap supplies might only offer 1 mA resolution (or worse), but it looks like the supply shown in this video has a resolution of 100 μA, so that shouldn't be an issue.
Cool video, with the perfect amount of detail. Thank you.
Really all you need is to rig up an incandescent light bulb socket to the power in. The light bulb will feedback any over wattage and protect anything you are working on
A bulb limiter may protect your house from burning down but I wouldn't guarantee no component failures. In the time it takes a lightbulb to flash a lot can happen in the world of electronics. Some of it rather irreversible too.
@@1pcfred true. But it's better than nothing I guess
@@Guitarhero1000 current limiting can certainly avert major disasters. But as far as stopping damage entirely goes I wouldn't bet the farm on that. It does not take much current to take out sensitive circuit elements.
@@1pcfred that's why I use a bulb and a variac together ...
@@ArchetypalCat bringing equipment up slowly can save it. The bulb is a good idea to monitor the current. Exceeding current is what burns stuff out.
For a minute there until you spoke, I was thinking Garth would pop in from behind the camera and I was being transported into another Wayne's World video on Public Access Television.
This is the video I was looking for, thanks buddy and TH-cam suggestions
Just came across this - thanks Mr. @TechTangents ! Some used audio gear I have acquired is in an unknown state, so I'll be doing the variac and light bulb trick because all of them are most likely old enough to have old-school, linear power supplies, not the modern, switching power supplies ("switchers"). Of course, I'll crack them open just to make sure. It is good that you mention that switchers cannot have their voltages slowly ramped up without possible bad outcomes.
I have also one piece of my own, pro audio gear that is about 25 years old but was powered on only once for a few minutes to make sure it worked - and then shelved and never used again. It will be very interesting to see what state its caps are in.
Wow = @Mr. Carlson himself commented somewhere below - he da E-Man !
Another factor in speed of leakage current slowdown at 15:09 might be different capacitance values as the circuit is basically a high pass filter loaded by resistance of the analog meter. Oh and if you want to automate without multimeter you could consider a source measure unit, they have more current ranges and some can go up to 1000V (but yeah expensive sadly). Nice vid thanks.
use a filament bulb, they have ptc resistance characteristic... low when cold/low voltage across, rising with applied voltage, very useful as current limiters, semi stabilisers
what about that using that funky "CC" mode in a power supply?
@@WestEast3259585 For the typical power supply the current we want (
Thanks, I didn't know that you could repair caps like this until your video.
Great content and delivery, had to like and sub. Cheers from Calgary.
Offtopic: At the end of the video the dot matrix printer... I haven't seen one in over 20 years now.. I miss the sound of it. LOL! I want one...again..
Ontopic: great video! That's why some old stuff just don't work any more after setting them away for 20+ years...
Thank you for Recycling these!
Great video bro! Very well explained.
This is wealth of information. Thanks!
That was fascinating, thanks for showing us.
I deal with AC variable speed motor drives and occasionally have to reform the capacitors in them. Manufacturer recommends to do it every 2 years if they've been powered off. They are usually 450V capacitors in a series/parallel setup. I use an 120V AC variac, a 600V:120V transformer in reverse and connect to the AC input of the system. The drives have a pre-charge diode and resistor for normal starts and a thyristor bridge on the 3ph power in. I can bring the voltage from 0 to 600Vac (0 to about 850Vdc) using a standard 120V wall power. I have also done a similar manual setup with a 600V rectifier and a rather large resistor (I think it was 10ohm, like 100W) to make my own DC supply for models that did not have a rectifier circuit.
With small capacitors, probably not worth the hassle. The big beefy ones though, definitely worth trying if you got the equipment for it. Those guys are NOT cheap, and are often difficult to source!
it can be worth it if the cap is an old vintage type and you want to preserve originality as much as possible , i've reformed many signal couplers successfuly, in some cases the circuit will self reform them, after a while
Pioneer amps from the early 80's ....
20.000yF/63V .... oh yes ... they cost if GOOD ones.
A lot of guitar nuts would disagree. They freak out when someone has hacked up a vintage amplifier and replaced the original tone capacitors with newer variants.
@@cajunfid : In this case : replace the guitar guy !
Drummers are way cooler 🤣😜
@@cajunfid if these tone caps are only in low level signal part of the circuit, no high dc across them, unlikely to need replacing anyway,
Thank you very kindly for everything you do, Mr. Shelby Technology Tangents.
OMG with this talent, you should be explaining policies to pass bills in the parliament
Nice one! Just what a sceptic like me needed :) A few times you made it sound like a cap is supposed to “have a load” or “be a load” which is a bit confusing, but in this context it does make a little bit of sense, considering we’re talking about ESR.
I still have a hard time finding a use case since it’ll still be easier to replace an old one and less risky - time is money and a new one is less likely to blow up 3 months later leaving the neighborhood soaked in electrolytic.
Sometimes the original caps might be a big part of the aesthetic though - in that case reforming is your only bet.
Always good to have another tool in your arsenal, thanks!
Like he said in the video, it's definitely a viable option for the large electrolytics (like soup can sized or bigger) that used to be in old products - those things are super $$$$ to replace. For your average up to 4700 uF caps you find in modern stuff, most of the reasons they've failed is because they were garbage quality / china off-brand no name garbage to begin with. Best to replace with name brand quality caps - and they cost ~$1 or so anyway, so who cares.
15:46 - Those might be oil-filled caps,in which case..I don't believe reforming is needed,or even possible,since they aren't electrolytic. Side note: Old oil-filled caps were often filled with PCB (Polychlorinated Biphenyl).. If they are leaky,dispose of them properly! That stuff is nasty and hazardous.
Excellent video! I like that ammeter method.
Great video very informative ! Caps are magical things. I'm always looking for caps when opening a device. When you see some Elnas or Nichicons or Mundorfs or Black Gates or Philips BCs in a high end device they are simply gorgeous.
Wow, great video, thank you!
Take it from a EE that has worked with Vacuum tube equipment to TTL/CMOS. Never use reformed capacitors, you're just putting on a band-aid. Think about the ESR as well. Reforming a cap doesn't repair the high ESR the cap has developed. Also how much is your time worth? Want to wait hours for some caps to reform or go spend 10 bucks on replacements and 10 - 15 minutes replacing them? Also why reform something that will fail with in a few minutes, hours or days that will in turn destroy other parts. Just keep in mind when a cap fails it shorts. I honestly laugh my hole off when people bring me stuff that they reformed a 10 cent cap but killed a ROM IC. After thinking of what I just said, yeah, reform caps and keep bringing me it to fix it so I can charge large amounts of cold hard cash.
I love how this has been a debate since forever. CuriousMarc has been in the game for a long time and he swears by reforming if they’re old enough! I myself have no opinion.
Every cap I've ever reformed failed the ESR on my Tel-ohmike. They check good on capacitance with a digital tester, but fail under load.
Actually it does restore the ESR of a capacitor. So be more wrong why don't you?
This is a super interesting discussion, and a great explanation (or part of one) why the 12v ac adapter I bought 10 years ago stopped delivering 12V 2A and became a questionable 11V 250mA supply. If you have a project that calls for lots of coulombs and you have the e-waste, I say go for it. I can envision a few scenarios for it but honestly I would probably just go with new caps for anything serious. I'm not an expert, I don't have all day, and capacitors are cheap. 👍
Heared that for very big commercial ones, so the example that I remember was a capacitor that was big as a coffee cup and used for a ~220V AC-motor inverter, but for the smaler standard electrolyte capacitors i always got told that they 'dry out' and in the same company where i saw the big one that has to be reformed after some weeks of not using it, they changed ALL Elkos as a standard procedure when refurbishing electronic modules.
Really interesting. I knew what a capacitor is and that they sometimes fail but that was about it. I now know a bit more and what to look out for on a failed capacitor. Interesting to learn about reforming and when to try it v replace. Many thanks for taking the time to make this and share your knowledge.
I doubt I'll ever be needing to do it, but now I know. Thanks!
Great video on reforming caps.
Thank you for making this
OMG I can't wait to see the inside of capacitors!!!!
Perfect timing. I have a SWTPC 6800 which has a minibar Coke can-sized electrolytic that needs reforming.
In the simple method you just connect a capacitor to a variable PSU through a resistor with a meter across the resistor to monitor the voltage drop. Begin at the lowest voltage and note the meter reading. When the meter reaches zero increase the PSU voltage in a step wise fashion and again watch the meter. When it drops again increase the voltage again. Keep going in steps until you've reached the capacitor's rated voltage and then hold it there until the meter's again dropped and then hold it there. It is recommended to form for one minute for each month out of service. I generally call it good after an hour myself.
I studied Electrical engineering and even I didn't knew about reforming capacitors. Though to my excuse, I was mostly into writing software, designing digital circuity and radio/em stuff.
VERY NICE!
NO EXCUSE!!! :P
Interesting plus the Compaq hat is cool and the dot-matrix printer snapped me back a substantial number of years. Thumbs up for educational.
Great video and explanations!
Great work. Like always
Great video. I didn’t realize that you could do this with capacitors.
SOME capacitors, SOMETIMES.
I learned something new today! 👍
Very good explanation and description of the process and chemical situation (coming from a 35 year EE analog design engineer) but the prices of just replacing the capacitors with newer ones makes it hard to justify the time spent. Mr Carlson ( on Utube) is a master of replacing especially very old capacitors including mostly non-electrolytic capacitors. I think your video is actually very educational and between the lines, give more reasons to replace than reform (especially the unknow ESR factor you mention in the video. The newer switching power supplies actually rely on low ESR type capacitors to limit the internal temperature of modern capacitors.
Very well made video. Easy to understand and follow.
I would have hoped that you got your hands on a professional RLC meter to actually do a before/after comparison of a reformed capacitor. You don't have to buy one for thousands of dollars, there are places that rent out equipment like that. We even have companies that send us test equipment for free in a "try before you buy" kind of deal, so we can play with the instruments for a few weeks and then decide if we want to buy it, or just give it back with no cost or strings attached.
Thank you! This video gave me a true nerdgasm! Haven’t had one of those in a good while! 14:10
Perfect studio 👍👍👍👍
This was fantastic. New subscriber now. :)
Before I even watch, I can only imagine this being especially useful on large, high quality caps. If I see a no-name failing, I'd replace regardless.
Very instructive 🤔 I have a suggestion to automate this with a regulated power supply: set your lab power supply to current limitation mode and set the voltage to the target voltage. The regulation will gradually up the voltage with respect to the current limit.
To be tested before reforming the caps of your vo stage Marshall 😏
I just wrote a whole rant about that a few minutes ago, now I see you mention it far down in the comments, yes that is the simplest way to do it
Brilliant , nice one
Thank you, thank you, THANK YOU!
As an electrical engineer BSMEE I have heard of capacitor reconditioning and reforming. I have worked on and designed Amplifiers and power supplies ( Linear and scan rectified)and Frequency generators and Programmable control hardware for 40 years.
In the field it is easier and cheaper just to replace a suspect capacitor. On vintage equipment is another story. If the capacitor is not easily replaceable because its in accessible or because modern capacitors are much smaller for the same value uF or even for ascetics, Then reforming may be an option. Problem with reforming is you do not know the quality the final result and reading the uf capacitance value is no indication. It may last a day or a year.
But a new Capacitor is always better than reforming an old one.
You post no credentials. But you provided a in depth wel explained explanation of what is happening on the inside of a capacitor.
Suggest you do a video on the capacitance of components that are not capacitors, like a Zener diode, a MOV, a step up transformer, A Transistor, An DIP IC socket, a touchscreen and why this is so.
One of my fav youtube channels man. Keep it up. Also wish i could grow hair and copy that flow.
I've seen shango066 reform capacitors in old TVs many times with a variac and light bulb, so I had a vague idea of how it works. Never expected to find a tutorial.
wow i have no idea who you are, and i watch a lot of youtube, but I think i watched a game video from you before. you are really really really good at youtube, education, tech... honestly bro idk why you're only at 163k subs, you should be over 200k and probably over 400k.
I daily a Pioneer SX-1250 from 1976 I use as my PC speakers that still has many of the original capacitors. (The last time it was serviced was in the 90's I think but they appeared to only do work on the power supply)
Still working along just fine.
First, you are still using it. Second, Pioneer and most of the better hifi manufacturers used good components.
I have a Tektronix 2465B scope from the mid '80s that is still working fine. Of course TEK used the best components available, although that damned Dallas Semiconductor static RAM/EEPROM with its internal battery is going to cause problems sooner or later.
@@johncasteel1780 Yes, I'm still using it Your Oscilloscope sounds cool. Did some googling and it sounds like that has a bit of a cult following.
Wow…..(head scratching begins?)
That was insightful.
I am a Armature Radio operator and I have a lot of old amps and radios. I have always used a variac to bring the amp back on line.