I have a 26 year old Acurus DIA-100 amplifier and I am considering replacing the 2 CDE power supply filter capacitors. These caps are 18,000uf, 70V and an odd size at about 44mm in diameter and 95mm long. I'm having trouble finding replacements that will meet the voltage requirement and also fit the space; 70V is an uncommon value and the newer 75V and 80V caps that are available are too large in diameter at 50mm to fit the space.
The power supply is 60V unregulated, 63V caps would fit but I'm not sure this leave enough margin for voltage fluctuations, could use some advice on this.
Another option would be to use a bank of smaller capacitors in parallel mounted on on circuit board like this one and tucked in where the current caps are. Would there be any issues using a bank of capacitors? I know it'll lower the ESR, which seems like a good thing but want to make sure it won't cause any unwanted side effects.
I could try to shoehorn the larger, modern filter capacitors in between the transformer and the amplifier boards but it seems kludgy and I'd prefer to make use of the space that's already there.
Any advice would be much appreciated.
The power supply is 60V unregulated, 63V caps would fit but I'm not sure this leave enough margin for voltage fluctuations, could use some advice on this.
Another option would be to use a bank of smaller capacitors in parallel mounted on on circuit board like this one and tucked in where the current caps are. Would there be any issues using a bank of capacitors? I know it'll lower the ESR, which seems like a good thing but want to make sure it won't cause any unwanted side effects.
I could try to shoehorn the larger, modern filter capacitors in between the transformer and the amplifier boards but it seems kludgy and I'd prefer to make use of the space that's already there.
Any advice would be much appreciated.
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The amp works fine, right? So just add caps in parallel to the existing caps.
The long wires from PS caps to the main amp boards make irrelevant any low ESR upstream.
63V caps are fine here, as there is typically a surge rating on top.
I've done this with an Acurus 100x3:
https://www.diyaudio.com/community/threads/need-advice-for-upgrading-an-acurus-dia-100-amp.134411/
The long wires from PS caps to the main amp boards make irrelevant any low ESR upstream.
63V caps are fine here, as there is typically a surge rating on top.
I've done this with an Acurus 100x3:
https://www.diyaudio.com/community/threads/need-advice-for-upgrading-an-acurus-dia-100-amp.134411/
Unless there's an issue with those capacitors, making a problem with the amp, I'd leave well enough alone.
People need to get their head out of the "internet driven" rage about "recapping" things that are not showing signs of trouble.
It's gotten so rediculous, the hype, the worry, the obsession... for no real reason.
Stop listening to others "online" because 90% of the time they are not technicians, they simply repeat what some other goofball "said to do, because...."
People need to get their head out of the "internet driven" rage about "recapping" things that are not showing signs of trouble.
It's gotten so rediculous, the hype, the worry, the obsession... for no real reason.
Stop listening to others "online" because 90% of the time they are not technicians, they simply repeat what some other goofball "said to do, because...."
Yes, amp works fine, thanks for the link, definitely gave me some good ideas for my amp.
I know people have mixed feelings about replacing caps, but there are more than few well respected goofballs out their who recommend replacing caps after 20 years or so, I figure it can only improve the sound at this point.
I know people have mixed feelings about replacing caps, but there are more than few well respected goofballs out their who recommend replacing caps after 20 years or so, I figure it can only improve the sound at this point.
Those "goofballs" spoken of...
What are their qualifications?.... any certifications?
Proof?
Or is it just typing on a screen by someone.....
Just because someone online spouts advice, and even creates a "following", doesn't qualify them to drive others to do what they recommend.
It's words on a screen, lord only knows who they really are.... that's the reality of things.
This "recapping craze" started back in 2003 or so, when a company manufactured defective electrolytic capacitors - you can search and read from a site about the dreaded bad caps era - https://www.badcaps.net/forum/
Before that, this "recapping" thing was not even talked about.
Yet..... it grew into an enormous craze through the internet.
And I've watched it grow, being on the internet myself since Windows 3.1 in the early 1990's.
Yes, caps can go bad, but not at all for the reasons that people say, or invent in their minds.
In many cases, people who delve into this nutty craze wind up actually harming the equipment, when they should have left it alone.
Testing the caps and if they read within tolerence, leave them be.
Caps made well before the "bad caps era" are not trouble, in fact the quality is better than current versions.
I'm not going to change your mind, you're likely gonna do whatever anyway.....
But after being in the service business including audio and video, after 45 years and professionally, I speak from experience.
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i too have over 40 years of servicing audio and power systems.
modern caps typically last longer and have lower ESR - a good bet is long life 105C caps for general use and ELNA bipolars for signal path. When I do a cap replacement becuase some of the originals are aging out I do them all, because the others will go in the next few years. If you want to keep bringing it back every few years to get the next batch of caps going bad changed you can follow wise old tech’s advice. They will all age out, it’s just a mater of time and temperature. Me ? I get them all out in one repair and then it’s good for the next 20/30 years.
modern caps typically last longer and have lower ESR - a good bet is long life 105C caps for general use and ELNA bipolars for signal path. When I do a cap replacement becuase some of the originals are aging out I do them all, because the others will go in the next few years. If you want to keep bringing it back every few years to get the next batch of caps going bad changed you can follow wise old tech’s advice. They will all age out, it’s just a mater of time and temperature. Me ? I get them all out in one repair and then it’s good for the next 20/30 years.
No.
What's this "every few years" stuff?
I've had plenty of "28 year old" -PLUS amps in the shop, and rarely because of aged caps.
My experience was with blown transistors due to abuse, or poor design.
And yes, I check for faulty caps.
I stand by my earlier comments about the internet-driven DRIVEL and BS over replacing caps that don't need replacing.
How do you know that?
While I can agree with you on changing all capacitors in some instances, I can't agree on modern caps lasting longer firstly because you need to wait some more years .The true measure of how long a capacitor lasts is done after leaving it unused for a decade or at least 5 years not just aging stress tests.Very reputable industrial 105 degrees caps would fail this test loosing up to 50% of their capacitance in 5...10 years with some getting shorted within 10 years or having increased leakage such that it will be impossible to use them again.
Some series from Rubycon , Nippon Chemicon , Sanyo and Siemens( epcos) as well as older Nichicon bipolar muse can last up to 30 years on the shelf while more modern low esr for industrial use 105 celsius Panasonic loose without doing anything at all...
Wiseoldtech - I'm going with Nelson Pass's advice on replacing power supply capacitors after 15-20 years and Darren Meyer's advice on restoring vintage components, not to mention my own experience replacing capacitors in older gear and finding more than a few capacitors that don't measure well or leak.
I respectfully disagree with you and I'm not looking to start a flame war about proactive capacitor replacement; that subject has been beaten to death and honestly isn't that interesting.
I respectfully disagree with you and I'm not looking to start a flame war about proactive capacitor replacement; that subject has been beaten to death and honestly isn't that interesting.
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Once upon a time japanese capacitors were made in Japan...now japanese capacitors are made in China...
I suppose with this newfangled Capacitor Replacement Theory some folk have heard about on the internet, some larger older but still functional caps might get tossed out prematurely in favor of smaller denser caps, but that's the march of progress.
Foggily I remember the badcaps.net years as a kind of Apple Computer promotion surrounded by some impossible industrial espionage story about some secret ingredient. We got a free macbook. Maybe it was a lot different for Windows folk?
And who's going to mention the "Pi Wars" (CRC v CLC) kicked off in 1992-1994 by who else, the incorrigible goofball Nelson Pass, and still hotly raging? CLC won, but still you see CRC everywhere...?
Foggily I remember the badcaps.net years as a kind of Apple Computer promotion surrounded by some impossible industrial espionage story about some secret ingredient. We got a free macbook. Maybe it was a lot different for Windows folk?
And who's going to mention the "Pi Wars" (CRC v CLC) kicked off in 1992-1994 by who else, the incorrigible goofball Nelson Pass, and still hotly raging? CLC won, but still you see CRC everywhere...?
I went through a capacitor replacement phase before I was on this internet. It seems like a natural progression for someone with just enough knowledge to get themselves into trouble. Glad now that eventually I destroyed a component that I'd not long spent a week's pay on. It made me see my capacitor collection in a different light.
Best thing would to just leave everything as it is - you say that it is working fine and there is nothing about the bulk filtering caps that should change that anytime soon. The Cornell Dubilier used in your amp are good for a lot more abuse at only 20 years old than they get in a lite duty application such as yours - especially since they are well ventilated and should not be exposed to temperatures near their rating. If you do feel they need to be replaced, go with a quality 20K or 22K screw type with a voltage rating of at least 75V and use a mounting ring to mount them vertically between the control shafts - Mouser or Digikey sells both.
Hal
Hal
I can't believe I clicked like on that post.
My first amp was producing 1/4 rated power and 10x rated harmonic distortion at that power, when I took it to the McIntosh clinic in 1971. As suggested by the Mc salesman, new e-caps got it up to 2/3 rated power, new rectifier tube took it the rest of the way. New cathode bias cap kept the tubes from red plating.
A S100 amp (produced 1980) that went silent in a service in 2018 was producing 1/50 rated power the next Monday. 2 watts. You can measure on speaker with an analog ac voltmeter, P=(v^2)/Z where z is speaker impedance. Typically 4/3 what resistance the speaker measures. Amp power rating is in the product sales brochure. I exercise the amp with a FM radio & an earphone to dual RCA plug adapter or dual 1/4 phone plug adapter. Turn radio down to 1/4 volume, the earphone can go up to 7 vac. You want about 1.5 to 2 vac going in the amp.
Polite music, no peaks, is a sign of power limitation. If you're listening to strumma strumma singer/guitar players, there weren't any peaks anyway. Classical music has drums, tinkly bells, cymbals, pianos with high crest factor. Takes power to reproduce those. Amps that produce too much highs or lows can have dried up coupler or filter circuit caps.
Rather than buying $$$ screw top caps, I parallel various snap-in caps on a bare board and parallel them with 18 ga wire. I cut the board out of nema-c laminate from mcmaster. That way it doesn't have to be any particular size. I screw the board to the chassis with #6 screws and elastic stop nuts. I use air tubing as standoffs. Cap voltage rating should be 5/4 to 4/3 the nominal rail voltage. I buy caps rated >3000 hours service life so I don't have to do the job again 3 times the way I had to do on my original amp bought used in 1970. Store shelf caps from TV parts stores were ****. Don't buy ebay or alibaba caps, and I find Panasonic/nichicon/rubicon/kemet/vishay caps of long service life have never failed to maintain OEM power & HD specs. I find when one cap goes bad, all the others in the amp are due. Oxygen never sleeps and the sealant in e-caps is a rubber compound. Overaged coupler caps can cause weird frequency response or distortion. There are certain pros that remove & measure ESR on every cap, only replacing the "bad" ones. This insures the amp is always broken, as caps evaporate out the water one by one. If I do one I do them all, unless the amp shows signs of being a dog that was never used. If replacing many e-caps, change 2 at a time and test for improvement. Amateurs make a lot of bad solder joints or can install caps backwards if you failed to mark the board before removal. If your 2 caps made the amp worse, you know just where your mistake was.
Other failure points in geriatric amps are oxidized connectors, and volume or tone control pots.
Happy listening and perhaps repairing.
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I don't replace e-caps on an amp that doesn't have problems. Takes 5 minutes to measure power out on the speaker at max volume with analog voltmeter. Power okay, sound is balanced, piano sounds like hammers are hitting strings (PING!) no problem. Power low sound tinny or boomy or too polite, there is a problem likely associated with ecaps. Blown output transistors are not much in the home market after Sinclair, although ebay/alibaba wonders with no heatsink have resurrected the insta-fail market. Drivers can go in 70's 80's consumer grade receivers etc because they needed heat sinks from day one but the company was too cheap to install them.
I've bought a couple of ebay dog amps that were 30 years old and never used. Symptom, squeaky clean, original box, doesn't work right because of a bad solder joint from the factory. After I find the bad solder joint. voila, working amp with 30 year old caps. Peavey purchased e-caps that didn't deteriorate unused on the shelf as badly as consumer grade ****. DTV converters, e-bike motor drives, cheapo brands of TVs etc, consumers are lucky to get 2 years out of those ecaps, even sitting still.
After all is said and done, the bottom line is WHO the vender(s) was that the manufacturer chose for parts for its products.
And even then, the vender's quality control and production batches at that time are all contributers.
This should be obvious and known to people in the service business and anyone doung repairs.
And even then, the vender's quality control and production batches at that time are all contributers.
This should be obvious and known to people in the service business and anyone doung repairs.
Ironic follow-up to the discussion...this week a friend brought to me a non-functioning Cyrus III amp from the mid-90's. It was freshly back from a "highly regarded" local tech with many decades of experience. He couldn't figure out the problem and gave the amp back to my friend after charging a hefty "diagnostic fee."
I spent some time downloading and reviewing service manuals, probing voltages, and removing and testing components only to find that you guessed it, an electrolytic capacitor had failed. Was it leaking? No. Bulging: Nah. Was it a top quality brand? Yes. Elna, even made in Japan.
What's my point? Had the "highly regarded" tech simply replaced all of the 20 or so aged electrolytic capacitors he could have solved the problem in under an hour and for maybe $20 in parts and left my friend with a much more reliable amp to boot. Heck, I could have done the same had I had the parts around, luckily I did have the one value of capacitor that was needed to get the amp going again.
Given the age of the amp and the complete failure of the cap in question, the other caps likely aren't in much better shape. He will probably be back 6 months from now with another failure, but maybe that's the point?
I spent some time downloading and reviewing service manuals, probing voltages, and removing and testing components only to find that you guessed it, an electrolytic capacitor had failed. Was it leaking? No. Bulging: Nah. Was it a top quality brand? Yes. Elna, even made in Japan.
What's my point? Had the "highly regarded" tech simply replaced all of the 20 or so aged electrolytic capacitors he could have solved the problem in under an hour and for maybe $20 in parts and left my friend with a much more reliable amp to boot. Heck, I could have done the same had I had the parts around, luckily I did have the one value of capacitor that was needed to get the amp going again.
Given the age of the amp and the complete failure of the cap in question, the other caps likely aren't in much better shape. He will probably be back 6 months from now with another failure, but maybe that's the point?
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Highly regarded techs, as a rule, do not fix things by starting out replacing a ton of parts hoping it cures the issue. In this case it might have, but it could just as easily have been a cracked copper trace and all the parts in the world wouldn't fix it.
That sir is an insult. I am sure there are some bad acts out there, but the vast majority of us make a good faith effort to serve our customers. We don't leave work half done just to get them to come back for more. I want my customers to come back, but because I served them well the first time, and now they trust me with their other gear too.
What if your tech takes your amp, replaces all your caps just because, and it doesn't fix it. Maybe all new output transistors. And heck, all the power resistors are probably heat stressed, change them. And eventually find a small space between traces bridged by a tiny bit of excess part lead So instead of just finding that short, you also got several hours of labor and a whole page parts list on your bill. Might not seem like such a great strategy.
Sometimes Tom Brady gets intercepted, Hank Aaron struck out from time to time. Doesn't make either one a bad player.
That sir is an insult. I am sure there are some bad acts out there, but the vast majority of us make a good faith effort to serve our customers. We don't leave work half done just to get them to come back for more. I want my customers to come back, but because I served them well the first time, and now they trust me with their other gear too.
What if your tech takes your amp, replaces all your caps just because, and it doesn't fix it. Maybe all new output transistors. And heck, all the power resistors are probably heat stressed, change them. And eventually find a small space between traces bridged by a tiny bit of excess part lead So instead of just finding that short, you also got several hours of labor and a whole page parts list on your bill. Might not seem like such a great strategy.
Sometimes Tom Brady gets intercepted, Hank Aaron struck out from time to time. Doesn't make either one a bad player.