Electrolytic Capacitor Reforming - Why and How To

[@jameslucas6589]

I enjoy your videos a lot. I have learned a lot. I would love to tackle restoration of my Marantz 4400 someday. I barely have my head around some A5 things, and someday I’ll try to advance to solid state. But I’ve owned that 4400 from day one, and restored they are getting 2x what I paid for it in 1975. Sure wish you would go back to a full screen format. Thanks a lot for your work.

[@kardeef33317]

Keep in mind about this before you reform any caps. Also somestimes a reformed cap will fail (dead short) hours,days and sometimes weeks. Its a timebomb that you don't know when its going to go off on 30+ year old caps. When a cap fails it will become a dead short that will kill tubes and transformers.. The crapiest caps made today are usally better then the best ones made 40 or 50 years ago. Its sometimes better to spend a few bucks on a new cap instead of 100's on tubes and transformers.

[@reynir8448]

you are absolutely right

[@picanazo420]

i have a defibrilator capacitor(32uf 6000v) of 30 years and i charged it to more or less 5 kv and discharged it several times and nothing happened, but the capacitance has drooped a bit like to 26uf but it takes an hour to recover to 31uf or32uf

[@qzorn4440]

A very interesting video. AC FVD motor drives have large electrolytic capacitors and the spare drive may sit on the shelf for years. It is recommended to re-form the drive caps. Thanks.

[@xminusone1]

Man, people in the comments are asking legitimate questions and you don't bother yourself to even explain and answer them. It should be easy for you to answer. It's not like you have millions of subscribers. I repair and restore electronic equipment since the 80's and many people have legitimate questions.

[@Arlisonatis]

What is the dielectric typically used in 50's - 70's can caps? I've restuffed a few cans and it would be nice to know what precautions I should be using handling it if any.

[@anthonycosta1776]

I have a ge superadio. Made in the early 80s. Plays perfectly. How should I maintain these caps. Please let me know. Thank you.

[@richardgray8593]

Thanks. Excellent presentation!

[@khanhso5113]

Hello, I have an Angel EL34 Push Pull Amply Tube with the Power Transformer burn out. Would you help Me where to buy and replace it? Thank You for any input.

[@VentureWelding]

Can these types of capacitors, when blown or have gone bad, result with continuity between positive and negative pins?

[@victorvalmus8135]

Where can you find a reasonably priced 400v DC power supply?

[@littlebritain64]

I have read about capacitors on sale from China and similar that are not of the same value described outside. They, if the new is true, hide a little one with lower value. How may I buy good, safe capacitors for a reasonable price? Thanks a lot guys.

[@classicsamusaran3817]

i have electrolytic capacitors mounted on electronic devices from 1990, how long can these devices remain unused and without the electrolytic capacitors failing due to disuse?

[@classicsamusaran3817]

Electrolytic capacitors mounted on electronic circuits of devices manufactured after 1990 can remain unused for as long as possible without this disuse causing failures and depolarization in the electrolytic capacitors?

[@tommybewick]

Great overview, thanks. do you have a recommendation for a good quality esr meter? I have a Solar high voltage tester that's been restored. thanks.

[@hypercubitus4565]

K2bew I use the BK Precision 880 LCR Meter. I also have the Peak Atlas ESR70. If you never plan on measuring inductors then I would go with the ESR70. It is inexpensive, rather accurate, and couldn't be simpler to use.

[@tommybewick]

Hypercubitus ; thanks

[@chonle9931]

First,you don’t reform the lyric cap,you’re instead re-form it, Then try to get the MepcoElectra apnote on lyric cap to understand The cap itself and decide. I am using Tek,Hp,Fluke tube type all these yrs w/o cap issue,Why? Thermal management,so it’s case/case basis.”replace them all” If you can afford.

[@erin19030]

What gibberish are you selling now?

[@jamieostrowski4447]

I don't know about that 50 uA value. Even a 2018 Nichicon 500 volt capacitor spec says that 500 uA is acceptable. I think 50 uA sounds very difficult to achieve. 22uF/450V Nichicon, the leakage current is specified as “After 1 minute’s application of rated voltage at 20°C, leakage current is not more than 0.04CV+100 (µA) ” which is =(0 .04x 22µF x 450) + 100µA = 396µA+100µA = 496µA ~ 500µA.

[@jon_byler]

My understanding is that is the maximum allowed leakage current for it to be considered serviceable, but closer to that or over, and you’ll want to consider replacing. Electrolytics can be re-formed, but may have limited lifespan after that. Depends on what conditions they saw in service and how long they’ve been run, and how much water has evaporated out of the electrolyte. My understanding is that under 50ua, and it’s probably an indication that it still has much life in it. I’ve got a capacitor (50uf 350V) I just reformed that has relatively high leakage at the rated voltage (200ua after half hour reforming at 10% above rated voltage) but under 20ua at the voltage that it will likely see in circuit, which is half the rated voltage at most. It’s from an old (50-60 years?) uhf converter that I got that was new in box, so I figured it probably hasn’t been abused other than possible storage in someone’s attic, but the box was pristine looking, so I’m figuring that wasn’t the case. I’m doing some DIY stuff and it’s got a tube socket, chassis, transformer and power supply capacitor, and even through it’s probably 50-60 years old, I’m not out anything major it it fails. I’m curious to see how long it lasts after I put it in service.

[@marknash7113]

Hey Mark! Iv'e become a bit obsessed with your channel of late. Great job breaking down this controversial subject into real world practicality. Many have tried, few have succeeded. I recall the same type of experience in EE school, with a guy who was an audiophile. I've been captivated by tube electronics since. One question that I can't quite wrap my head around is how a NOS cap shelved for decades can be more dried out than a well used thermally cycled at high voltage one or a used and then shelved/stored unit. I'm with you on the chemistry, it may be a bit complex. Any thoughts?

[@1mctous]

Electrolytic caps and batteries have common elements, as Mark stated here. Just as some batteries can be effectively recharged and some can't, some electrolytic caps can be reformed and some can't. I wouldn't push my luck beyond 30 years old, especially with the power supply filter caps.

[@grhinson]

Correct me if I am wrong; but, I have heard some people prefer somewhat leaky caps in their guitar amps, giving it a distinct sound, even if it is harder on the circuit. I suppose a listening test would be needed.

[@DaveMcAnulty]

You could always use a good capacitor and insert a resistor instead. If that leaky capacitor continues to degrade, you'll have a loud bang and magic smoke in your future.

[@ke4est]

I fully agree Dave. People are just asking for trouble in the future. If you want that "sound" stick a high MegaOhm resistor across it. Move the value up and down until you find the sound you want. Just stock up on tubes, and audio output transformers. :)

[@ncilmo]

LOL That's true regarding the tubes and transformers.

[@ncilmo]

In dealing with Leslie amplifiers, we use 6550 output tubes. A new pair of current production output tubes run $100. One vintage Tung Sol 6550 can cost $250 to $350 depending on if it is a grey plate or Black plate. A new coupling cap cost less than $1. Do the math. LOLOLOLOLOOL

[@erin19030]

That's their drugs talking.

[@Thomasp671]

Hi There Blueglow I have some questions for you and would like to see if I could have a Skype video chat with you if that is possible ?

[@wavegallery]

Hello. I'm reforming a chassis-mount 2500uF 50v Roederstein cap dated of November 1969. It's been reforming for 9 straight days now at rated voltage via a 10k resistor and a microammeter. No heating during process, and leakage current has been slowly decreasing but it still not stable, typically varying from 2uA to about 8uA. Can I expect it to become stable if leave it more time? Any thoughts? Thanks

[@jasbirsingh4583]

Hello sir Can I replace 16v 1000uf to 16v 3300uf ? Atx power supply for car amplifier

[@xminusone1]

No. It will cause the B+ voltage to rise and operate at a higher voltage than it supposed to.

[@paul.alarner6410]

whats your website addy?,supprised its not linked!

[@erin19030]

Reforming caps are like leaky condemns.

[@lelandclayton5462]

Never reform caps. Just replace them and save yourself some heart ache. If you want to keep the old look then restuff the old caps by gutting them and slide in a new cap. If you do that be sure to leave a note or some other tech down the road will just clip out all of your hard work.

[@misterhat5823]

I have to disagree. A lot of older equipment will have an old capacitor fail on powerup. But, if reformed will work for years. I see reforming as preventing failure, not a fix for a bad capacitor.

[@garybevis8691]

@@misterhat5823 or it may reform your transformer into a charcoal briquette without notice. Capacitors are so cheap it is foolish to not just replace the caps. Bad advice is to reform electrolytic capacitors. You have no idea the state of the electrolyte or the plates, or the dielectric oxide. You have a better chance of destroying equipment than preserving it by so called mythical reforming.

[@misterhat5823]

@@garybevis8691Reforming is not mythical. That's how they are made. Bad advice is blanket advice.

[@garybevis8691]

Mister Hat that is not how capacitors are made that is how old equipment is destroyed. It's clear you have some misinformed bias regarding the sketchy paractice of taking an unnecessary risk with vintage elelctrincs. Anyone who restores vintage electronics for some time understands this.

[@erin19030]

Re stuffing is not good either. Looks can kill!

[@paulkielt9301]

I think the Method 3 is definitely not the way to go!

[@synthrodriguez7518]

Yeah, I'd never dream of doing it that way.

[@erin19030]

Method 3 is the best way! Who are you trying to fool?

[@jimcatanzaro7808]

Just buy new caps reforming is junk why because you will have large amounts of esr

[@mbak7801]

If you buy new caps from a legitimate supplier you do not know how long they have sat on a shelf for. A value that is not sold too often could easily be five years and up. Checking ESR and measuring leakage is worth doing before putting into equipment. Something 50 years old I would not bother with but neither would I trust components even if from a known good supplier.

[@nor4277]

Reforming I call lazy ,capacitors aren't all that expensive ,I have had good result from cheap caps from Ali express,eBay bandgood.I don't want to have to come back and Eddie it later ,that's twice the work new caps are safer too.you no when a bad cap goes bad it can take out other stuff.but to each there own .I want to make my radios safe as I no how as a novice.

[@erin19030]

Are you totally illiterate?