Big 'audio' capacitor source - Page 1
Forum section: electronics / general

author: Rufus
author_rank: Super Contributor
timestamp: October 22, 2013, 04:13:36 pm
content: Was given a sick AV amplifier the other day. Think I have figured out the main fault but one of the PSU capacitors is bulging and looks like it might have vented a bit. Not having much luck finding a replacement.They look like the attached except 71v rating. 15000uF, 105C, 35mm x 75mm can, 2 pins 10mm pitch. I measure 64vdc on them so 63v parts are not really gong to cut it.It is a pretty small can for the capacitance and voltage, bigger than about 37x80mm won't fit. Any suggestions for a source?

author: minime72706
author_rank: Frequent Contributor
timestamp: October 22, 2013, 04:18:41 pm
content: 71V rating ... my god ... what?

author: Monkeh
author_rank: Super Contributor
timestamp: October 22, 2013, 04:43:01 pm
content: Quote from: minime72706 on October 22, 2013, 04:18:41 pmYes, people use non-standard as well as peak ratings. Don't hurt yourself with the concept.

author: kfitch42
author_rank: Frequent Contributor
timestamp: October 22, 2013, 05:03:06 pm
content: So I started putting your requirements into octopart, and stopped when it got down to just a single result:http://octopart.com/partsearch#search/requestData&q=capacitor&rangedfilters=0.015&rangedfilters=0.03&rangedfilters=71&rangedfilters=150&rangedfilters=0.0349&rangedfilters=0.08&rangedfilters=0.0349&rangedfilters=0.037P.S.Sorry, but I think you will have to copy/paste the URL. I can't figure out how to get the forum to deal with an URL that contains square brackets.P.P.S.Ooops that cap is only 85 C rated. I clicked on the data sheet and somehow missed that the first time I skimmed it.

author: Rufus
author_rank: Super Contributor
timestamp: October 22, 2013, 05:16:32 pm
content: Quote from: kfitch42 on October 22, 2013, 05:03:06 pmI managed to get the same result but it is a glitch, the part is 143mm high and has screw terminals anyway. The can is really small for the ratings and a lot of cans that size with snap-in pins have 4 of them. If it wasn't difficult I wouldn't be asking

author: Monkeh
author_rank: Super Contributor
timestamp: October 22, 2013, 05:18:39 pm
content: Quote from: kfitch42 on October 22, 2013, 05:03:06 pmLike this:http://goo.gl/AklrXz

author: kfitch42
author_rank: Frequent Contributor
timestamp: October 22, 2013, 05:29:52 pm
content: Quote from: Rufus on October 22, 2013, 05:16:32 pmAnd I thought I was sooooo slick finding that one thing you had missed.I suspect this part has its diameter listed as both diameter and height in the octopart DB. I guess, at this point, the most help I can be is to say: DREMEL TIME!!!Quote from: Monkeh on October 22, 2013, 05:18:39 pmYup, that is much better ... I double failed here. Guess I will just go sit in the corner and be quiet.

author: Smokey
author_rank: Super Contributor
timestamp: October 22, 2013, 05:32:18 pm
content: The replacement doesn't have to be exactly the same specs. You can always go UP in voltage rating. Generally speaking you can also go up in capacitance. Make sure you check the other specs to make sure the replacement isn't drastically different, but especially in an audio amp situations the big caps are just to keep the supply line from being inductive and for bulk storage and bridge filtering.Also the fact that those are "Audio grade Custom" caps shouldn't deter you from swapping those out with quality general purpose caps from a reputable manufacturer. If you can actually measure a difference in the distortion I would be really surprised. There are a couple threads here about Magical Audio Quality capacitors if you want to get the general consensus on that.

author: mariush
author_rank: Super Contributor
timestamp: October 22, 2013, 06:14:33 pm
content: 71v rating is really weird, but going with 63v rated capacitors would be too small if you measure 64v on the capacitors now.I would go with 80v rated capacitors, or higher. Considering you have a restriction of 37x80 mm, you might have to go down in capacitance a bit.You can find 12000uF 80v capacitors fitting your restrictions easily (except lead spacing, but you can improvise there, just solder wires or something), though they're a bit expensive :http://www.digikey.com/product-detail/en/ECE-T1KP123EA/P10032-ND/258698http://www.digikey.com/product-detail/en/382LX123M080A082/338-2108-ND/2295338They're not 105c but they're 3000h @ 85c which is decent, and should last a while. And I wouldn't worry about 12000uF vs 15000uF, it would probably only matter if you really push that amp to max volume or something like that.Alternatively... and I wouldn't consider this a proper fix... maybe you get 64v on the capacitors due to higher than usual voltage in your house... say 240-245v if you're on 230v mains, or 120v if you're in US. Maybe you could hack in a few beefy diodes between the rectifier and the dc capacitors to get the voltage down to about 61 volts, so that you could then use 63v rated capacitors, but then you'd have voltage drop x current dissipated on each diode and it's another mess...here's some 63v rated capacitorshttp://www.digikey.com/product-detail/en/383LX153M063A062/338-2025-ND/2256628http://www.digikey.com/product-detail/en/ECE-T1JA183EA/P10639-ND/272779etc there's others..

author: JuKu
author_rank: Frequent Contributor
timestamp: October 23, 2013, 10:44:16 am
content: Have you asked the manufacturer?

author: dr_p
author_rank: Frequent Contributor
timestamp: October 23, 2013, 10:59:13 am
content: 2 for 23$

author: wraper
author_rank: Unknown
timestamp: October 23, 2013, 11:43:26 am
content: Quote from: dr_p on October 23, 2013, 10:59:13 amWith 90% probability to be fakes.

author: Psi
author_rank: Super Contributor
timestamp: October 23, 2013, 12:18:06 pm
content: Quote from: minime72706 on October 22, 2013, 04:18:41 pmIt's when they give a decimal point that you have to worry.

author: kfitch42
author_rank: Frequent Contributor
timestamp: October 23, 2013, 01:04:28 pm
content: Quote from: dr_p on October 23, 2013, 10:59:13 am85C rating, and no given physical dimensions (which seems to be the real difficult part)Taking some quick measurements (obviously these will be very approximate) from the image:pin spacing 80 pixelsdiameter ~430 pixels at bottom ~360 at topheight ~680 pixelsGiven the noticeable foreshortening/projection, the height will be wrong. But my brain isn't awake enough right now to figure out the direction of the wrongness (too tall/short)Lets assume they have the desired 10mm pin spacing, giving 8 pixels per mm.So a reasonable-ish estimate of size is 54mm diameter, and 85mm height.EDIT:Got myself some tea to wake up, and ended up staring at the mug as I rotated it a bit (thanfully, before I put tea in it). Now I think my height estimate is a minimum, and a more accurate height estimate is closer to 92mm.

author: Rufus
author_rank: Super Contributor
timestamp: October 23, 2013, 03:01:01 pm
content: Quote from: JuKu on October 23, 2013, 10:44:16 amYou are directed to one of their distributors who offer a repair service and they said no suggesting I try Farnel or RS Components - lol.Quote from: wraper on October 23, 2013, 11:43:26 amI had found those and agree there is a risk of them being fake.I don't believe the ratings on the existing capacitors (unless is it for a stupid 200 hour at 105C life or something). The amp was made in 2006 and has had typical living room use the caps shouldn't even be tired. Looks like I will have to settle for 12000uF and 85C, but, they are still difficult to source.

author: macboy
author_rank: Super Contributor
timestamp: October 24, 2013, 02:49:39 pm
content: I have never done business with them, but you might tryhttp://www.percyaudio.com/They carry "audio" grade capacitors such as Nichicon Gold Tune and Super Through.

author: dyazdani
author_rank: Newbie
timestamp: October 26, 2013, 03:47:48 pm
content: I've used the Panasonics in other audio amplifier power circuits with good results.

author: minime72706
author_rank: Frequent Contributor
timestamp: November 15, 2013, 05:27:17 am
content: Did you succeed in finding some replacements?

author: Rufus
author_rank: Super Contributor
timestamp: November 15, 2013, 06:22:16 am
content: Quote from: minime72706 on November 15, 2013, 05:27:17 amI ended up with some some claiming to be NIPPON CHEMi-CON ESMH800VSN153MA80T from an ebay seller in Germany. Right size, 80v, only 85C.

author: calexanian
author_rank: Super Contributor
timestamp: November 16, 2013, 04:39:55 am
content: In my experience once you get past 4700uf lower ESR becomes more important. Check the specs on the caps closely cause thats where they "GET YOU" sometimes. Also if this is like a 1ohm stable amp or something like that you are really in for it. I will sometimes use sprague powerlytics of lower capacitance but great ESR and other characteristics, squeeze them in, or parallel smaller ones and actually get better performance than larger cap values. They can really deliver the current in a huge way. Also 71 volts you ask?? Well thats easy! when using a 100 volt center tap transformer rectified and subtract the rectifier drop and bingo, just a hair under 71 volts, but just over 70. Your green new design engineer says call this spec out for 71 volts cause 70 just wont do!!!! hahahaha.. Of course this is just in jest and a swipe at nervous new engineers. O0Good luck and have fun!

author: TMM
author_rank: Frequent Contributor
timestamp: November 16, 2013, 05:43:07 am
content: Depends what it is for. If it's just a home audio amp driving some 8ohm speakers at moderate levels then almost any old cap should be fine. An ordinary 12mF 80V cap is going to have pretty low ESR.If it's for a PA system driving 1ohm loads then maybe some low ESR caps are warranted.

author: calexanian
author_rank: Super Contributor
timestamp: November 16, 2013, 06:40:37 am
content: I am assuming it is something top dollar from the sounds of it. Otherwise all you really need is enough to handle the ripple.

author: Rufus
author_rank: Super Contributor
timestamp: November 17, 2013, 01:05:07 am
content: I finally got round to fixing it today.About an hour and a half and 80 screws to get out the board that had the main fault which was a failing voltage regulator as I suspected. Then another half hour and 20 screws to get out the main board with the capacitors.The old caps measured OK but the end of one was bulging and I didn't want to risk it considering the time I knew it would take to pull it apart.

author: calexanian
author_rank: Super Contributor
timestamp: November 17, 2013, 02:47:23 am
content: Good deal.

author: Rufus
author_rank: Super Contributor
timestamp: November 17, 2013, 05:04:31 pm
content: Quote from: Rufus on November 17, 2013, 01:05:07 amWhen deciding if I should keep or throw the old caps I noticed the bulging one rattled. I cut the end off and saw the attached. There is no visible sign of it venting and it still measures 13500uF with D of about 0.17 at 100Hz, about the same as the other one - strange.

author: SeanB
author_rank: Super Contributor
timestamp: November 17, 2013, 05:13:43 pm
content: Running out of electrolyte and going dry. Normally you would find the interior full of a very thick liquid electrolyte but with time the water making it up diffuses out of the seals and the self healing of the oxide film breaks the water into hydrogen and oxygen which diffuses out the seals as well.

author: calexanian
author_rank: Super Contributor
timestamp: November 17, 2013, 07:27:26 pm
content: For important stuff i know I don't ever want to go into again I will re form the caps and monitor current. It really does make a difference. This is particularly useful when you are operating a cap at WELL BELOW its voltage as it may never form completely in use. Don't assume it was properly formed when made. Cap manufacturers are notorious for testing at low voltage and never really giving a proper forming and power soak.

author: Rufus
author_rank: Super Contributor
timestamp: November 17, 2013, 08:30:45 pm
content: Quote from: SeanB on November 17, 2013, 05:13:43 pmSo I weighed them, the 'bad' one was 76.9g the other 77.4g.I opened up the other one and it has just as must free space in the can. It didn't rattle because the winding was better wedged against the end of the can. These are 9 years old and don't run particularly hot.Wish I had noticed earlier and weighed the replacements.

author: calexanian
author_rank: Super Contributor
timestamp: November 17, 2013, 08:42:48 pm
content: Weighing them is not really a good method because the electrolyte these days is in gel form and the tightness of the wrap has a lot to do with how much is there.. electrical tests like monitoring ripple voltage and current, leakage, capacitance, etc etc etc, are better indicators of cap health. There are even "DRY" electrolytic caps which is not really accurate, but how they were marketed. I think they are all gone now..

author: wraper
author_rank: Unknown
timestamp: November 18, 2013, 02:22:39 am
content: Looks perfectly good inside. Wet paper, liquid will come out if you squeeze that paper. Are you sure it was really bulging? I have some new big ELNA caps and top of them is not completely flat, a little bit bulging, ~1mm higher at the center compared to the sides..