Replacing capacitors in vintage equipment
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- เผยแพร่เมื่อ 26 ก.ย. 2024
- After 20 years of faithful service, this viewer wants to know if he should replace the capacitors in his equipment and what to look for in new ones. Paul gives us some insights into when it's a good time to switch and what to replace them with. Have a question you want to ask Paul? www.psaudio.com...
I am getting close to publishing my memoir! It's called 99% True and it is chock full of adventures, debauchery, struggles, heartwarming stories, triumphs and failures, great belly laughs, and a peek inside the high-end audio industry you've never known before.
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Many years ago I was troubleshooting a car amplifier when an electrolytic cap exploded. The metal can (part of the cap) hit me right in the middle of an eye and within a couple of minutes I went blind in that eye, all I could see was light or dark. Luckily I was wearing a hard contact lens when this happened and the lens spread the force enough so that there wasn't more damage to my cornea. The lens itself tore. (Yes, a hard lens, not a soft one). The cure was to spend 3 days in the hospital with both eyes bandaged, the good eye had to be bandaged to keep them both from moving. The cap wasn't in backwards, the amp's internal voltage "booster" somehow was putting out much higher voltage than it was designed for and higher than the cap's rating. Since then I never work close to live electronic equipment without safety glasses.
30ish years ago a colleague and I were developing a new filter for a SMPSU. We fitted a new electrolytic cap, switched on and got a fantastic result, 10mV of ripple pk-pk. We thought we had hit the sweet spot and congratulated ourselves on our success when suddenly we heard a brief hiss then a big bang and like Pauls story, we got covered in bits of confetti and almost fell over ourselves, we jumped that badly. We did laugh about it although our boss wasn't quitter so amused.
Good story, they usually just short out on your wrist and blow a hole through your flesh like a .22 cal bullet.
@@gboates I have seen many blown capacitors and never got injured by them. Certainly a direct hit into an eye is a differnt story but i never experienced more than mediocre hit.
I've had them blow up in my face. I always wore some cheap magnifying glasses when working in a repair shop.
Yep those old capacitors without the ridges on the top shoot the can like a bullet. I had it once shoot a dent in my ceiling.
I want to add one more caution after watching the video. Paul is talking mostly about electrolytic capacitors in baseband audio circuits. But never blindly re-cap tuners, phono EQ circuits, tape EQ or bias circuits, basically anything where the cap tolerance is critical. If you do you will probably throw the unit out of alignment, especially a tuner. Small mica and ceramic caps are very rare to fail. And they can have tolerances from 5% to 20% especially in consumer gear. When the unit is aligned at the factory, those parts tolerances are nulled out of the circuit as a whole. If you replace parts, re-alignment is often required. And today it may be hard to find a service shop with FM tuner test gear as well as someone who knows how to use it. Electrolytic caps in tuner circuits are usually just power supply bypass caps and OK to replace but again it's best to stay out of RF and even audio EQ circuits unless you know for sure the component is bad.
Couldn't agree more
I’m a vintage hifi guy. Golden rule is if it sounds great you don’t need to replace anything 👍
until it goes bang
Maybe.... but I'd never leave it on and alone. You may hear a boom, and you may only hear the smoke alarm going off after flames are emanating from your amp. The power supply protection fuses don't always blow first.
I am too, but I recap all my vintage gear. From mixing consoles to tape recorders to effects racks. Rather keep things in good working order, avoid future cap leakage (with inevitable trace corrosion). Every piece of gear was improved after replacing the aging electrolytics. Lower THD, precise filters/EQ points, lower SNR... not to mention the massive improvement in reliability. I think of electrolytic caps like failing gaskets on an old car. Sure, the car will still run and drive, but it's nowhere near it's initial performance.
@@lllllllllllllllllllll1lll1 Also I don't know about electrolytic capacitors, but I sure remember that specially computers upto 2009 had HUGE problems with solid capacitors because for ages they kept using bad "fake" capacitors branded as jap solid caps while they weren't and many computer hardware had crazy problems which got fixed from 2009 and up.
I know amps don't use much solid caps, but the electronic parts for other stuff like decoders and whatever probably used them a lot specially in the first HDMI ones and most likely those first could also been suffering of "fake" caps being advertised like good high quality Jap solid caps which could lead to any sort of problem.
ps: Most likely electrolytic caps also suffered a lot with fake stuff at least in PC hardware cause I saw many motherboards with blown or leaking caps that didn't even had that much years back then. And nowadays specially when trying to buy electronic components there's a gazillion amount of fake chips and whatever sadly which is really hard to know WTF we are even buying sadly...
I have a 1976 Heathkit AA-1506 120 watt stereo audio amplifier, and when checking recently I found that the two 250uf 4 volt Bi-Polar Electrolytic capacitors now had odd readings of approximately 450uf and 340uf. I replaced each of those with a bi-polar 220uf in parallel with a 30uf bi-polar. Every other cap seemed to be okay. In my 1976 Soundcraftsmen PE-2217 Equalizer/Pre-Amp, one electrolytic capacitor had become an open circuit, and a few other electrolytic capacitors were of the wrong value. A production line boo boo. Some 2.2uf caps were in place of 4.7uf caps. In turn, the left side equalizer lowest band filter was not the same as the one on the rights side, and the two Phono Pre-Amp boards were not identical, due to these too having these wrong cap values, and not only that but wrong values in different positions for each board. Thank goodness I had managed to find the schematics to know what the proper values were to be. Meanwhile, all the other electrolytic capacitors, despite being 48 years old, surprisingly were all slightly higher than the specified value, but well within the tolerance rating.
Back in '07, I sent in a HK Citation 11 preamp (1973) to the repair shop. Among other things, they replaced all the leaking caps, tuned it up to factory specs. When I got it back, the sound was glorious.
Mouser has a great selection of caps, as Paul said go for the low ESR and make sure you get the polarity correct!
bak when I was a bench tech I worked next to Vinny who was one of our senior techs. He was running up the variac on a new unit and about 2/3's of the way up he uttered oh shit, before he could get that big variac turned down a tantalum cap that was backwards launched itself - A slug rocketed out of that chassis and shattered the two 8 ft fluorescent lamps above the bench. We both froze but had the presence of mind to close our eyes as we got showered with glass from the shattered tubes.
he later said he felt the variac groan because of the load that backwards cap cause but could not spin the 280v 20a 3 phase variac down fast enough.
Variac plus current limiting device like a light bulb in series is always a good idea.
In electronics class the ceiling was full of holes, when we got bored sometimes we would hook up an old can cap backwards,good times.
We used to leave charged caps lying around on the bench in lab, 600v oil/paper caps will hold a charge for a very long time.
i used to to all the testing on the oil filled radar power supplies we built. We used 0.5uf 25kv caps in these supplies. Radar draws very short slugs of current so you don't need huge power supply caps in the supply. These caps were about 4X6 and9" tall (including the ceramic terminals with 10-32 threads), they came packed 6 to a box and usually came with a shorting strap across the terminals. If you leave an unshorted cap on the bench overnight it will have a substantial charge on it the next morning if the air is dry.
One day we got bunch of these caps in without shorting straps. The girl in the stockroom dropped the razor knife she was using to open the box across one of the caps, a fair sized chunk was burned off the blade by the arc. From then on Jane made me open all oil filled cap boxes and put shorting straps on them.
Another thing to take into account when determining if you should replace caps is actually how little the component has been used. Specifically if it has been sitting without power to the caps for years. Non-use can dry a cap out too, as use actually works the electrolytic, keeping it in its intended state. And as stated in the video, excessive heat kills them by drying them out.
The rated voltage should also not exceed the working voltage too much, as that will be detrimental to the electrolyte too
Thanks for posting. Interesting story here. When I was in high school I was taking electronics in a vocational school. Well my instructor was teaching one day about capacitors four students thought it would be funny to hook the caps up and increase the voltage well over the printed max value. And you guessed it they were thrown out of class. So polarity makes all the difference. My instructor was Ex- Air Force. I thought his decision was fair. Again thanks for posting.
If you live in Toronto, ‘Ring Audio’ specializes in vintage audio. The store repairs, restores and sells vintage gear. They will swap out you capacitors for you. I had been a customer of Rings until about 5 years ago, when all of my vintage gear was replaced by new high-end stuff. You’ll love the store.
True. I lived in Toronto for three years in the mid-80s. I bought the turntable for my first component system at Ring, in 1986. Very good people! It was (is) a used, modified Rega Planar 3. They set me up with a new Nagaoka MP-11 Boron cartridge. May be the best purchase of my life! It's sort of lo-fi hi-fi, sort of a workhorse? It's the only turntable I've had, it's here with me now, I use it lots. Same cartridge and everything. I live in Vancouver now. I recently had the Rega serviced at The Turntable Shop in North Vancouver. Nick is a gem, he totally knew about Ring Audio.
If you replace them make sure the polarity is the same as the old one. polarity is sometimes marked wrong on circuit boards.
Hey Paul - far as i know i ‘invented’ the variable height workstation. I worked for Acadia university in canada. The acadia advantage was an ibm partnership which brought 5,000 laptops on campus around 1997. Our faculty needed something to prevent back issues during 3 hr evening classes. The manufacturer was InLine Systems from... you guessed it - Toronto Canada
I have restored quite a few 1960s and 70s stereo components. And I am fortunate to have acquired a used but very good Sencore LCR meter. Most of the caps I check are still perfectly good. Now not everybody wants to go buy an ESR meter although there are some good low cost units on Amazon. And blindly re-capping a piece won't hurt anything, provided you don't accidently do other damage. But as modern caps are as much as 50% smaller physically for the same value and voltage rating, that can be a problem for large chassis mounted electrolytics. Yes you can kludge in the new smaller caps but if the old parts measure good. I just leave them as-is. Now this is gear that gets very little use and again before I get pounced on here, there is nothing wrong with re-capping a vintage piece of gear and is the best option for day to day usage. My point is only that many of these 70s Japanese caps are still perfectly good today.
When I was in electronics technical school, we had an ex-Army instructor who gave us a demonstration of the power of a 100uf 25V rated cap wired backwards in a circuit. Within seconds, the cap began to emit gases then exploded. He had put the entire thing in a protective enclosure, so no one got hurt, but no one was expecting the bang we got that day. I learned my lesson without having to learn that lesson; check and double-check that replacement's polarity!
Man, i asked the same question just a couple of days ago.
I srsly thought "Hey wow, they replyed to my question" and than it was another one with the same.
Only difference, my gear is 40 years old but works and looks like out of factory since yesterday.
Man I miss the old days of FM radio. Me, and my friends growing up, used to not only spend hours in front of our radios. But we would talk about it all the time, we recorded it, and shared it too. We had college stations (WRIU from URI, and WBRU from Brown University), and WCOZ out of Boston. And plenty of other great stations here too (Rhode Island, I was born in Newport). Every Sunday night we used to stay up late listening to Dr. Demento at very low volume, so our parents wouldn't know. Heck even the top 40 on the weekends was good back then. Thankfully a lot of this was preserved, and can still be heard, but it's not the same of course. We had no idea how good we had it back in the day, before the world became so corporate.
A good way to describe what out of spec capacitor do, is to say they turn themselves into a resistor, especially those old paper in wax/oil dc blocking capacitor.
Good electrolytic capacitor would include Nichicon UPW-UPM high temperature for psu, panasonic FH series, kemet, sprague, Illinois TTA for axial equipment, they're more expensive, but it looks so much better.
Cross over circuits in speakers also contain electrolytic capacitors. Old speakers will "die" because of aged electrolytics. Don't throw the speakers away when this happens. Just have the capacitors replaced. Other parts like resistors and inductors will normally last forever.
Low ESR caps are mostly used in switching power supplies where the resistance matters to the feedback loop. In linear supplies that usually means they can heat up with large ripple currents and in time dry out quicker, but they don't make things sound worse.
Paul, a place in Minneapolis, Brown Inst. Was a great electronics/radio school/trade school, after making it to the 3rd quarter were we staring working on power projects , we had the fun, or embarrassment if installing the different kind if caps. The larger the cap , the bigger the pop and many kids , including myself ,blew ourselves on our respective asses when a good sized cap blew up.we kerned fast to watch polarity. Fun as hell back in 81
Keep it. Restore it. Love it. Or sell it for a profit. The old, good gear, is fully restorable and is appreciating. Keep the faith.
I want to work there! It would be a dream come true to be able to earn a living working with top notch audio gear.
Ahh, a man can dream...🤤❤
Chris, I fully agree with you, I am now living my dream, I got fired as a X-Ray tech from a troubled business. I got hired by my friends at a world known audio company, and I am working part time and love it! I fell into it and it is fun going there!
I just want a job where quality is job 1. I was a tech with AT&T and the old days things we ret done the right way. Everyone followed the BSP's (Bell SysytemPractices).the
As Paul can attest, many times the cost of a device's capacitors is the driving factor in the final MSRP, and can easily double the price.
Man, I wish I had you as a professor in my college days.
I have a pair of klipsch chorus speakers and want to recap them,looking high and low on the net with no luck getting the same values,talked to crites and he wants $90 +shipping to Thailand plus exchange rate and import duty.....$180 cnd for 8 caps....ouch!!! Any idea where I could purchase replacements... 7 uf and 68 uf 100 volt,and 2 uf 250 volts.....
Paul,
You are missing out on a great use for these desks in your videos - you could put sketches on the part toward the camera and then raise the desk to illustrate your point, and then lower the desk back down to finish your monologue.
I read that Aragon used to seal their capacitors, so I imagine they might last a bit longer. But what do I know?
Love the 4K video quality. Keep it up!
Spot on. To answer the question: "is it worth doing"? In most cases, yes absolutely. As for the DIY approach, not many of us are keen on that. I suppose with an old easily replaced unit, it is ok, but I would not dare try it for fear of screwing something up on one of classic monsters of old. I'd rather have a qualified person do it. There in lies the problem though, not many of those around at all.
Having a qualified person do it can run from $160 to $300. Still worth it at that point?........It depends. If you love the sound of your old unit then it may well be worth it. Also, you would be buying another 15, 20 years or maybe a bit more of service! Some units of old are very worth it. For example, I have a Sansui 8080db, circa something like 1973 and the sound of this thing rivals anything off the shelves today and some high-end units in the $10k to $15k range! I have had it go up against a couple of those and the rep said "don't ever get rid of that Sansui"! To get the sound of my Sansui in today's field I would have to spend at least $10k at minimum. It is just pure pleasure to listen with and right now with a pair of $1000 speakers hooked up it makes mince meat out of my reference system in progress!!!! A situation I hope to fix soon, but it has me worried.
I found a guy who can work on these things a couple years back, who has the credentials. I don't know if he is still around or not. I had him do a complete recap on the power and amp boards buying me at least 15 more years of service and likely more. It ran me about $250. For this thing, well worth it.
Question about the bipolar crossover caps orientation:
I was reading that bipolar caps in crossovers have an outer and an inner foil. And that the outer foil should be orientated to the negitive terminal. Something about the outer foil being suseptible to interference/distortion. Is it worth worrying about when replacing crossover caps?thanks for sharing yer wisdom, Hamish, Isle of Skye
We used to swap capacitors around on the first year Electronics student when they would come to class and turn your test message on the power supply would be on with a capacitor 15 volt on the 50 volt Supply with reverse polarity with reverse polarity. We got a real bang out of it! Lol
Hello guys!I want to recap my NAD 1155 preamp.My question is can i replace old electrolyte capacitors with new film capacitors with the same impedance and higher voltage.People say the voltage can be equal or higher,but the impedance should be the same...Thanks if anyone responds!!!
Come to Northeren, IL and talk to Heil, the man that invented quadrophonic PA systems for the big bands in the early 70,s...Meet him and seen his treasure chest of tube amps with many original caps still. Some people who watch, actually know what is what.
I have a old pioneer sa 5500 II I'm wanting to do a complete overhaul on. If for nothing else just for the sake of the exspierience.
Now I do have a question...
After or during this process is it necessary to use a scope at any point?
Or do I just swap and solder??
Great information Paul
When I started out as a bech tech I had the bench next to Vinnie who had worked there for a long time. He was workig on a large rack mount series of supplies and had just turned the variac up on one, he said oh shit and turned the varaic down. It seems a large can cap was installed backwards and he felt the variac groan when it began to suck up current. As fast as he turned it down it was nit fast enough - the cap went off like a bomb and sent a slug of material into the overhead fluorescent lamps. We stood there withour eyes closed as we were showered with shattered glass from the lamps.
Fun times at Ridgemont high!
Thanks for post this Paul, people need to hear this, know about it, ~ sadly ~ people simply don't "get it"... I have this conversation ...all of the time..., people will fight and make excuses for how ~30 year old 'caps are testing fine' or whatever foolishness. The tough thing is that, these components ~ s l o w l y age ~. It is something that a person can barely recognize the gradual degradation. Like wrinkles on a face over time... they become *springs with no bounce... that soft and woolly vintage sound.* [YUCK!] I am always in favor of newer engineering, newer component technology... much that may not exist, back when these parts were made, sourced and equipment was built. I actually had the ARC service department offered to sell me "vintage (20 year old) OEM parts" for recapping an amp. I declined, was stunned by their comment, bordering ignorance. Mouser, was just a few clicks away... It is always ~incredibly rewarding~ to experience a favored old 'relic' spring back to life.
Very nice video, Paul, thank you!
An oil cap on one of my VTL 300s failed. The company told me to take it into a local dealer who replaced it. A few seconds after turning on, the cap spectacularly exploded spewing oil round the room. The dealer had apparently scratched the paint on the outside that serves as an insulator. Bea at VTL then let me take it to them to be put right.
I don't think you answered the part of the question as to what the effect on sound would be with old Caps?
I have a few vintage amps from the 70's. They still work fine, my hesitation to get them re-capped is finding the right guy that's going use the best caps. It's kinda scarey giving your presicious amp to a stranger, besides there aren't a lot of these guys left that do this kind of work anymore.
There's a good case to be made for becoming the right guy. I learnt soldering by dismembering junked TVs, radios and WW II army surplus back in the 60s. I used the salvaged parts to build short-wave radios, amplifiers and such. I recapped my favourite heavily modified kit amp twice before it became uneconomical to do so. The first SATA hard drive I purchased, I managed to break off the connector. I was a bit busy at the time and got a quote of $AU100 to solder a captive lead so I did it myself. I needed a magnifying headset to solder the rather close together signal leads. It cost me $AU20 and about a quarter of an hour of my time. DIY electronics is a heck of a lot of fun.
Do it yourself! Grab an old PCB from a garbage computer.. Get to soldering until you're comfortable.. Then start on your own gear.. Go slow the first time.. If you're still not comfortable, look at Audio Rehab near Los Angeles. They do a nice job on vintage gear (actually, on all gear).
De/Re-Soldering is a no-brainer!!! I've done several Dell Dimension 9200/XPS410 motherboards that had bad caps which would make the PC freeze & lock up. Just be sure to use de-solder braid with flux on it and an iron with enough heat since there is more metal to heat up on the larger caps! ...and *DEFINITELY* get your polarity correct!!! The voltage of the cap has to be the same but the microfarad (ufd) value can be equal or higher. Just make sure the can form factor and lead spacing is correct.
Get yourself a decent soldering iron (25-40W), or if the budget's big enough, soldering station. The latter includes a controller so you can vary the tip temperature. I have _occasionally_ regretted not getting a station over the ~40 years I've been using my iron. I have two tips, conical and chisel shape. It was as cheap as chips. The stand is just a piece of folded tin. But it has done everything I have asked of it including knocking up a signal tracer using a CMOS IC back in the 1980s (difficult because static electricity). Do NOT get a soldering gun. You're fixing electronics, not pots and pans! Go to an electronics parts supplier, not the local hardware store.
As well as desoldering braid, I have a desoldering pump (less than $AU10 new). Mine cost a dollar second-hand. Also useful is a pearl-catch for when you need to pick up small fiddly bits and pieces you can't reach with fingers. Also less than $AU10 new, but being the skinflint I am, mine cost a dollar second-hand.
I am an electronic technician with 22 years experience, most of it made on audio devices. I usually do that kind of work (capacitor job). I am doing it on a Harman Kardon Citation 17 Preamp and Citation 19 Power Amp right now. I live in NE Italy. If you are close enough you can send your stuff to me to repair. Ciao
Learn from mistakes.. Hopefully those of others.
Not only polarity but watch out value. I purchased bipolarised capacitors in 1992 value 9uF and they all the time until now (26years) measure unchanged 10uF Capacitors 9uF I buy new today they measure values 7-9 uF.; Capacitors I measure in gear produced in 1983 still are bigger than average eual by nominal values in shop today. So not always we regain capacity by obligatory replacement - usually we loose. . Which may be is not critical in supply but in crossovers or tone control it will make too much modification of timbre
Nice video. Reminds me I have a lot of vintage audio gear that is probably due for caps replacement around 20-25 years old.
Paul...l get the idea of replacing the "caps" on our amps, receivers etc., however, what about our 20 to 30 year old source components....CD, DVD etc? Billy Mike
Go to any online forum and you will find people who rip into their equipment and replace every cap and then power up the unit and WOW it doesn't work. Some will send up smoke signals or blow a fuse. If it ain't broke don't mess with it. Also many integrated circuits are static sensitive and any discharge will kill them.
Good video.. If you have a piece of gear that has a constant 60Hz hum (not a ground loop), look at the power supply caps. The hum is often a sign of failing power supply caps.
That's the sign of power supply caps getting old!
Salvador Rodenas Indeed!
Unless the item is a total POS and nested with ground loops. You'd be surprised how many products sometimes pricey ones are plagued with them.
I repurposed an old pair of 9v computer speakers into a headphone amp, I think they were from the early 90's, They drive my headphones VERY nicely off a battery however they do hum badly when I crank the volume up all the way, the hum got quieter when I replaced the wires and re-soldered some connections, however the caps are cheap generic ones, combined with age...I think its time to change them, and probably some transistors too.
I look after the sound gear at a couple of skating rinks, some of which is approaching 20 years old. One of those systems includes a digitally-controlled equalizer with +/- 15V internal supplies for the analog electronics, and one day the power supply cap on the -15V rail went open circuit suddenly, without any warning. The result was an 8V pk-pk 120Hz square wave coming out of its audio outputs, which gave everyone at the rink quite a scare. I wasn't there at the time, so fortunately they were able to find the power switch and shut it down.
When I repaired it, I replaced all 3 of the main supply caps. It's interesting that the warranty statement for that equipment explicitly denies warranty coverage for failed electrolytic caps.
Back when I was working a a bench tech I was working next to Vinnie who was working on a fussy power supply we made for Hughs ircraft. We were both doing our own thing when I heard Vinnie yell "shit" and shut down the 20a 3 phase variac as fast as he cound - but not quite fast enough. It seems there was a 180uf 40v tantalum cam in backwards and it took umbrage at the revere polarity..
That cap launched itself off the board like a rocket and went up into the 8 foot fluorescent fixture where it shattered both tubes. We both stood there with our eyes closed waiting for the shower to end. There was glass, paper and foil everywhere.
Whwen a tantalum cap lets go it does so with 10X the ferocity a regular electrolytic does. This was a three phase 400 HZ power supply and Vinnie felt the grunge in the variac but just couldn't get it powered down fast enough (a three phase 20a variac has some serious mass)
I got a pair of AR5s I bought new in the 70s, I had the 10 inch woofers tweeters n pots replaced in the 80s with original AR units when AR was still in Britain Dunstable I since replaced the tweeters bought from the US SH quite expensive SH but originals in early 2000s, I had them in my shed since I manage to buy a pair of AR9s SH the Real AR9s with a 10 n 12 inch woofers mid range 8 inch tweeter n super tweeter I found out trying my AR5s recently one of the electrolytic capacitors is gone finish of course I will replace both they are huge, someone said to me now days they have better caps not paper wound ones is this true? and how do I get the right one and will they degrade the sound quality in any way?
We have reached a point now where replacing silicon becomes just as important. Capacitors are not a blanket yes, many times what I remove test better than what I pull out… (70s ELNA capacitors)
2 Weeks ago, it was just a 470µF/35V and I was testing Amplifier Boards which I had put aside to desolder or put them to some use later. I connected a MP3 Player with some Music, and the Amp was playing fine. After about 2 Minutes I stood up, because something fell off the Table and "BAM!!.
In disbelief I looked at the PCB, mounted on a pretty good sized Cooler and 2 Thoughts were in my Head:
1.:" Wow, this whole Thing (the 4x6cm PCB) is on Fire! This is something new ... oh boy, these flames must be 10cm high! ..."
2.:" Hey, cool, the Music is still playing, the chip seems to be unharmed ..."
I had to act fast, and the only Idea I had was to use the same Technique which is used on Birthday Cakes: I blew the fire out :). Why did this happen? I think I was a little tired when I soldered this Amp together and just mounted the one Electrlytic the wrong way round. I hope, I never make such a Mistake at my Subwoofer PSU, because there are, amongst others, two 47000µF/ 50V Electrolytics in use. :)
The bigger issue is finding a competent technician locally to replace the amp caps. And if you find a competent technician out of town, you have to ship your amp, risking shipping damage both ways.
Great video but 20 years is often too late, if the component is exposed to heat, everything inside the casing will deteriorate much faster than say a "colder" DAC. (Krell amplifier for example run very hot and I did recap after 10 years, some of the caps were already gone...)
I found a guy on the local craigslist who reconditions vintage speakers... beautiful stuff :}. anyways, I asked him to measure some caps in old crossover circuits (as in 40-50 yrs old) and he did. unless the caps were physically damaged, no more than 10% deviation in capacitance.. Of course capacitance is not the whole story and as you said the degradation is also temperature related, but still, I was expecting the caps to be way more off specs
@@duroxkilo yeah back then everything was more reliable and had longevity
7:15 spirals of paper and cc........chunksss over the room!! LOL
Should one replace just the large electrolytic capacitors on the input power supply part of the amplifier? (I'm guessing its setting up the DC bus but I'm not an EE.) Or, do you need to go all out and replace every single cap in the entire amplifier? Thanks in advance.
I am so envious of that new Engineering work space. I can remember some pretty nasty work areas I was in. One of the Labs at MIT ( in the 60's ) this Phd guy had his own special filing system. He filed engineering drawings by levels of yellow. The oldest being the lowest in the stack and the yellowest. But if you ask him if he had drawing XYZ he'd be able to find that pretty quickly. Imagine working next to that. Also, he'd change his shirt once a week whether he needed to or not. Same goes for a shower or bath.
Aaaargh! I decided to retire early when I was in my 50s. My son was starting university, so I did too. The philosophy class I was in, a feral for reasons unknown decided he liked sitting next to me. The stink of stale urine and sweaty armpits on a hot day was appalling.
Excellent info, Paul, much thanks.
BTW, I wonder if it's a good idea to replace electrolytic capacitors with lower ESR solid state capacitors (e.g. tantalum, polymer film) of similar capacitance value and equal or higher temperature and voltage capabilities.
it could be a good idea to replace electrolytic caps with solid state ones, but solid states caps don't have high values rating like electrolytic (for example you can find 100 uF polymer but no higher value) or you have to put lots of caps in parallel. If you can do this big parallel on a DIY circuit where you have space enough to manage, you can't do that on a commercial amplifier where internal space is little. I have worked some 10 years as a electronic technician for cellular phones and we had great problems with tantalium caps so my advice is: avoid them. On signal path, if you can, use polyester or polypropilene caps. On power supply use just regular, fresh electrolytics and you are good to go
That story got me laughin xD
I love Paul's stories
Besides the capacitance value, the voltage rating, the physical dimensions, its polarity, and the ESR, as you mention, one should also pay attention to the tolerance of a cap, and really you don't want one that is worse rated than the original one was, (even though it was out of spec due to its age). If it was originally rated to be a +/-10% cap then you would want a new one that's at least that tight to its rated value, and NOT one that is rated at only +/-20 or 25%, etc., because the value under use and at various operating temperatures might change too much between its highest and lowest extremes for the circuit to always operate properly and within its designed specifications... Which leads me to another point...
Another very important thing to consider, especially in power supplies, or anywhere where a capacitor is mounted close to a heat sink of any kind, or where the capacitor is being used in a relatively warm or hot environment, is its temperature rating. You always want to go with a new one that has at least as high of a temperature rating as the original one had. If the original one was rated at 95°C then you would ONLY replace it with one that was rated equal to or higher than that, like 95 or 105°C, but never with one that is only rated for 85°C, otherwise the heat extremes of the associated circuit and the heat generated by the components around the capacitor would put too much stress on the cap, possibly causing it to fail prematurely! And if anyone takes the time and goes through the time consuming trouble to replace all of the electrolytic caps in any kind of audio component or other equipment, then you definitely don't want to have to do the job over again before the next capacitor life cycle is due! (Usually about 20-30 years for electrolytics if they're good quality ones, depending on how, when and where they are used.) (The effective lifespan is considerably longer than that for other types of caps normally. Most other types besides electrolytics potentially never need to be changed for the life of the overall equipment they're in unless they get an overvoltage power surge or physical or extreme temperature damage.)
Have a fan running to the amp , I have a £500 ONKYO AV AMP with a built in auto fan that has NEVER span so I use a PC fan external on top with a battery to cool it .
Comasitors are always ontop of the heatsinck to heet them up .
Short out the large caps with a 10k ohm 5 watt resistor before doing anything or you will experience the storage capacity of a large capacitor and it could kill you if you don't know this.
They also tend to "create" some charge again after being discharged, so the process should be done 2-3 successive times
not all electrolytic capacitors are polarized. i have some bipolar in the input section of one of my amps.
Maybe you can help us out Paul what is the best capacitor to replace a metal pack capacitor? Like in a leak tl12 I've heard paper in oil and that's always a good capacitor any other suggestions.
Yes, caps do go bad . I've replaced some before in a Kenwood and a few others.
My old 50's HMV no it's just a collection piece .
The exploding capacitor! That's a great story!
I've a bunch of those blue large can capacitors from old Mark Levinsons, Krells and Threshold mainly from Sprague and Mallory and they all have or exceed there initial caprating (uF).
Even the oldest ones from my Levinson ML-2's from with datecodes like 7852 meaning week 52 in 1978 (all Spragues Series 36DX) still exceed their initial capacitance rating.
I always understand that small electrolytics with low voltageratings get into problems first.
Some lytics like the brownred Roedersteins used in vintage Krell equipment dried out in a couple of years. Leaking their fluid corrosive substance on the PCB and corrode the coppertraces is far more serious like those Elna Long Life caps (see the irony) in the Adcom poweramps like the GFA-585.
When an old electrolytic, wax, or paper-in-oil cap is reading well above its rated value, the odds are good it's failing. Most RLC meters can't distinguish between leakage currents and high capacitance, so they give a false reading for old leaky capacitors that need to be replaced.
YES! the old electrolytic PS capacitors in vintage equipment because modern ones sound and perform better!
hi Paul greetings from Philippines,my question is irrelevant,just wanna ask if you know andrew jones personaly,coz you two have the same passion and for me the best audiophile masters in audio community.thanks
3:15 Electrolite capacitors are not used in AC power, they have polarity so you can use them only in DC power line
You are correct, but they smooth out the residual fluctuations in the (newly DC) voltage after the current has been converted from AC by passing it through a full bridge rectifier.
Is that standing desk for work force efficiency, or to control prairie dogging?
Hahaha
I am replacing a can-type electrolytic capacitor in my old Scott LK-30. After 40 years of storage, I decided that it was time to see if the unit worked, and the capacitor leaked and smoked up the room.
I need to know whether the outer can of the capacitor is supposed to be grounded to the chassis. The original was mounted on an insulator-type mounting plate. The new one came with a metal mounting plate. So with that mounting plate, the capacitor shell is grounded. Is that proper?
Thanks to anyone who might help.
Harry Jaeger
Longwood, FL
That should be correct. Just make sure the polarity of the electrolytic's two leads (+/-) are going to the correct parts of the circuit as if these are backwards the cap will heat and eventually explode.
Some repairman was a bit disgruntled I had the caps replaced in my Philips speakers from 1978. He said they were actually still fine dispite looking horrible to me on the outside.
i have an older pioneer receiver...the volume cuts out for short (5-8sec's) from time to time..but continues to play well..are the caps going? or something else?
may just need pots cleaned
A a hamradio operator who restores and uses vintage +/- 60 year old radios. I deal with lethal voltages. I have all of the necessary instruments do the the work. Learn what brands of cap age well and those that don't. A meter that shows ESR's is your friend.
Audio gear have full wave bridge rectifiers which means the negative part of the line voltage is rectified to become positive
In 11th grade I had a crotchity old teacher that taught the 2 period "career electronics" class. When explaining about electrolytic caps he purposely connected one backwards about ,5 in long x .25in dia then stood back as he turned on the power. It of course exploded bowing the sides of the metal trashcan. He explained that if it did this to the can what would happen in someones hand. somethign to definately be respectful of.
Question since you're an expert.. If I own high end audio equipment from Accuphase, dCS, and McIntosh and I want it to last as long as possible... is it better to leave it on all the time? or turn it off when not in use ... in terms of keeping the capacitors and other components health inside.. and last longest?
The only thing(s) in danger of going bad from not being on are the electrolytic capacitors. If you're running them more than a few hours a week that's good. I can't think of a reason to leave them on constantly, especially during a lightning storm.
@@seanwatts8342 so the on/off surge of power and heat/cool down cycles are less of an issue than leaving it on all the time?
@@Sams911 Unless you're dealing with a motor or you leave everything turned up full blast, inrush current isn't as much as you think.
Have a look at this circuitdigest.com/tutorial/what-is-inrush-current-and-how-to-limit-it
@@seanwatts8342 thanks man, much appreciated my brother.
@@Sams911 Let me clarify an exception: inrush current to a large transformer that does not have any kind of current limiting or "warm up" circuit can cause an audible 'thud' but you can reduce the chance of anything bad by using the 'standby' switch if you have one. OR if you're around all weekend and you know you'll turn it on and off several times, use the standby or even turn in down if you're on the phone, etc. Leaving it off for more than a day? Turn it completely off. Personally, I like to use a surge arrester and turn on the arrester, then the electronics - then electronics off --> surge arreser off. I'm not an EE, but my long time friend is an EE.
I just sent my speaker crossover in to have the electrolytic capacitors replaced. The speakers are 40 years old.
Been watching a few vintage amp repair vids lately. The amps seem to be in the 40 year old range (if not more) and only ones worth the effort of course. Anyway, even after 40 years they weren't replacing all the caps. In other words 20 years is probably unnecessarily aggressive.
Connecting a power transformer backwards, with a rectifier and a bunch of electrolytic filter caps connected isn't a very good idea also. Man, what an BENG when that poor diodes and caps (63V types) got 4.4kV on them. Chemical smelling goo on the wall, toxic smoke and diodes broken in tiny pieces. That's how I discovered as a 13 year old kid that transformers are not only for bringing Voltage down...
Hello from Lompoc, CA.
You are very nice person.
Working in TV, a fellow engineer would charge up old caps, when not expecting it... “ here, catch”. Or ones from a high power transmitter he would sneak up and crowbar that thing right behind you ..scare the crap out of you, but funny.
KBCO audio, why it's not the same. Two problems, the HD transmitter alongside the analog FM + the passing of their old chief engineer Bill Kleronomos. RIP Bill.
great vid
I largely agree with everything here but think Paul is being a bit pessimistic about timescale. Good quality electrolytics are usually fine for more than 30 years so long as they haven't been overvoltaged or exposed to much heat.
Haveyouevercheckedforleakage?
Since electrolytic capacitors wear out, is it possible to replace them with something that does not wear out? What about film capacitors?
Electrolytics generally have high capacitance values and are used for power supply filtering and decoupling. The other types of capacitors are used for other purposes and have lower capacitance values.
film caps are only usefull for small capacities up to say 100 microfarad . Typical elco's in amps or PSU can range up to 10,000 . At those values , a film cap would be unpractically large and extremely expensive (far beyond 1000 dollars).
Some low value coupling ones can be. Power supply/timer caps are gonna have to be electrolytic though due to the large values and or need for polarity. Generally I'd say if you find bipolar electrolytic caps in a circuit they can be safely replaced with film caps
Well I had no problem understanding you brokenstitch :-) I'd just add that there's plenty of online forums where people help each other out, not just electronics, but any hobby you care to name.
The capacitors on my old Sansui amp keep blowing very often. Its the ones that cause the LOUD cracking sound in the speakers. Im sure the technician replaces then with good quality caps of the correct specs. But he cannot figure out why this keeps happening. Does anyone have any clue?
Sounds to me like perhaps you need to up the voltage on those caps. If you can find higher voltage versions that'll fit, that's probably the way to go. You can have as high as you can fit.
use higher voltage, but the same capacitance
I have a Pioneer Spec 2 1978 power amp...do the caps need to be replaced
yes..
If you dont hear excess hum i bet caps are still good. Depends how this spec have been treated, was IT overheated etc
how cool is that paul,
What an exercise in marketing! Very well done!
I think the capacitors need to be replaced in my Yamaha 7.1ch receiver. Not sure what’s going on but it just doesn’t sound as clean and crisp as it used to. Though I have had this receiver for about 9 years now and there’s so many circuit boards in this unit, with it being a HDMI digital surround sound processor as well. Not sure if it’s worth fixing and just upgrade. If it was a vintage amplifier I could see it being worth it to fix it. I want my music playback and my surround sound seperate eventually and want to get a decent audiophile grade 2ch system with the preamplifier and power amplifier seperate.
Sounds like the right time-frame for a flood of cheap, crappy electros from China that hit the computer industry... Paying somebody to fix things these days never seems economically viable which saddens me. All that embodied energy going to landfill.
Jonathan Sturm unfortunately you’re right there. They don’t make electronics like they used to, or anything for that matter at least in the average consumer world. Things are made just to serve it’s purpose and then scrapped once it ceases to function properly. Having said that Yamaha do make some very high end equipment and have done for a very long time. I have seen first hand a rather expensive Yamaha integrated amplifier that retails at $9500AU with big beautiful looking VU meters on the front and a floating circuit design, very elegant piece of audio there!
The only Yamaha I ever owned was the piano I purchased for my first wife. Needless to say, she got the piano when we separated less than a year later. So it goes...
Do you recommend that I do this myself or send it to a shop? It weighs 45 lbs. so that’s gonna be pricey. Yes, I know how to solder. My amp is 30 years old and seems to sound fine to me. Will it sound better if I Re cap?
Не нужно чинить то что не сломано.
Who makes the desk?
From my experience amplifiers from the 80s have most capacitors still in spec. From the 70s about half will be off and 60s most are. However i never had a capacitor lose value, they always gain capacitance. My akai reel to reel player had almost every capacitor twice to triple the rated value
Agreed. Capacitance rarely goes down in value. Most old caps I find have risen in value as they dry up and age. Not sure what he’s talking about.
So, power supply caps will not make an audible difference unless they were going bad, and typically if they get out of spec and the amp knows this, it won't even power on. So, please don't expect that power supply caps would make any amp sound different, rather newer power supply caps would simply restore the amp to it's original designed specification (in the power supply section). Oh and yes, electrolytic caps do deteriorate over time. However I have some amps that are 25+ years old with all the original caps, and they still sound fine. I guess not all caps are created equal....
Only Spinal Tap has 10,000 Volt amplifiers LOL
I’ve never seen a capacitor explode. With stock fuses and common sense it’s almost impossible. Electrolytic capacitor’s insulation gets leaky, current increases and the fuse blows. Don’t boost the fuse, replace the old caps and Bob’s your uncle!
So meny PC motherboards died with bad caps, often they are like mushrooms or completely empty in the end. Audio equipment surviving 10+ years certainly have better caps than budget motherboards.
It wasn't just cheap MoBos that copped the bad caps problem a decade ago. ASUS, Apple, Dell... pretty much every manufacturer was hit.
Paul, why didn't you mention "capacitor forming?"
Hi Paul.. this is Frank from Singapore, million thanks for all the valuable knowledge off books. It will be awesome if my question catch your swift attention.. I got a power conditioner few months ago, wondering do I still need the original socket EMI noise filter in my dac and CD player ? It doesn't sound right to my ear , could that be over kill ? Or I should just take it off from dac or cdp? Pls advise.. good day..
PS audio must be a great place to work in
Do you get much stick over your name? 😂😂😂💩💩💩