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tromboc

Denon AVC-A1 power capacitors

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Hi everyone, 

Apologies if this is the wrong place to ask, I'm new here, and hope someone can help. I've got an older Denon AVC-A1 which has pregnant capacitors on the power supply. They are marked ELNA For Audio 15000uF 73V, however I can't find any reference to this spec capacitor anywhere. I'm just going to replace them with a bigger capacitor, or one with a higher voltage rating, whichever is cheapest, but my question is, do I really need an "audio" spec capacitor for this stage, I would have assumed if anything, ripple current would have been priority? Also, there are a HECK of a lot of caps around rated for 63V, am I ever going to see voltage that high in that section of my amp, or can I get away with lower rated caps?

TIA

EDIT: I shouldn't have trusted what I saw, according to service manuals they should be 71V rated and marked DENON.... these are likely fakes. Oh well no better time to replace them. Probably don't care so much about the previous questions considering they are readily available now.... Cheers

Edited by tromboc

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Do you know what you are doing, and this is an absolute genuine question - please dont take offence. this is a power supply you are working on feeding off AC mains. unless a qualified tech better off left to one.

 

denon is serviced by qualifi. be no reason they cant sort this out for you. denon are usually quite good with parts and service. they tend to use quite similar as well over the years in their range of gear and to replace mains caps I can imagine a pretty straight forward job.

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Do you know what you are doing, and this is an absolute genuine question - please dont take offence. this is a power supply you are working on feeding off AC mains. unless a qualified tech better off left to one.

 

denon is serviced by qualifi. be no reason they cant sort this out for you. denon are usually quite good with parts and service. they tend to use quite similar as well over the years in their range of gear and to replace mains caps I can imagine a pretty straight forward job.

I appreciate your concern, and am certainly not offended... However you said it yourself, it's a pretty straight forward job. I'm not a qualified technician, and this also isn't a $10k amp so I'm not inclined to pay the hourly fee, shipping costs and marked up replacement parts to have it diagnosed and repaired, likely writing it off economically, if I can potentially sort the issue myself. 

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I'd go for Caps with higher temperature and voltage and with lower ESR specs.

 

These Panasonic caps seems like a good option.

 

http://www.ebay.com/itm/2x-15000uF-80V-Radial-Snap-In-Mount-Electrolytic-Aluminum-Capacitor-mfd-DC-85C-/131737454219

Cheers for the tip, that's what I thought, just wanted to confirm with someone else. Been a while since I dabbled in this stuff.

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I appreciate your concern, and am certainly not offended... However you said it yourself, it's a pretty straight forward job. I'm not a qualified technician, and this also isn't a $10k amp so I'm not inclined to pay the hourly fee, shipping costs and marked up replacement parts to have it diagnosed and repaired, likely writing it off economically, if I can potentially sort the issue myself. 

 

 

its a straight forward job ....for a suitably qualified technician who knows what they are doing. it involves working on mains 230 V AC power supply sorry but unless appropriately qualified not something id suggest.

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its a straight forward job ....for a suitably qualified technician who knows what they are doing. it involves working on mains 230 V AC power supply sorry but unless appropriately qualified not something id suggest.

Fortunately I didn't ask the forum whether or not they think I should undertake my own repairs, based on their thorough knowledge of my own experience and skills, just for suggestions of replacement capacitors.  

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I wouldn't worry about the "audio grade" logo or label. Like someone said, for the psu of anything go for the lowest ESL and the highest temp.

One thing is for sure, you will definately not get away from a lower voltage and because it's bulge means that Cap has been exposed by over voltage or it's been stressed. That said I'd be looking for a 100V version and that will protect you from higher than usual mains voltage. And also if you are going to do it yourself, ensure that you take note of the polarity and the size, 100v 10,000-20,000uf are very big!

100v 15,000uf or any large capacity of this size are now harder and harder to source reliably. 100V 10,000uf would be easier to find. That's because electronic manufacturers are opting for smaller low powered devices and 100V 15,000uf are no longer in demand. To avoid fakes such as that on eBay I'd order via Mouser, Element 14, RS components and Digikey. They can guarrantee the supply.

Good luck!

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Thanks for the suggestions guys, I have a pair of 100V 105deg 15000uF on the way for similar money to the original spec which is nice!

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Make sure it fits. Too big = no good.

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Make sure it fits. Too big = no good.

You make it fit.. :P

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@@tromboc How do you know that the caps have failed? Have you measured them? Have the metal cans distorted, or just the plastic?

Edited by Zaphod Beeblebrox

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@@tromboc How do you know that the caps have failed? Have you measured them? Have the metal cans distorted, or just the plastic?

If you read the 1st post, it's in the 2nd sentence; I'm assuming that "a pregnant cap" Is a bulging cap....:P. But you never assume! :D

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If you read the 1st post, it's in the 2nd sentence; I'm assuming that "a pregnant cap" Is a bulging cap.... :P. But you never assume! :D

I read the post. IME, the vast majority of bulging caps aren't. It is just the plastic that has deformed. There is zero problem with the caps, apart from cosmetics. Measurements will reveal if there is a fault with the caps.

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I read the post. IME, the vast majority of bulging caps aren't. It is just the plastic that has deformed. There is zero problem with the caps, apart from cosmetics. Measurements will reveal if there is a fault with the caps.

I disagree with you on this via my experience. Bulging caps means that they have been stressed out, either the manufacturer has skipped on correct values due to cost savings or supply issues or its just down right age! I have no trust in the "Elna" brand as I saw many of this brand fail in psu that are not even for audio. Not many owners like myself are going to let a "bulging cap" go because it "measures " OK via a ESR meter or a capacitance meter. I don't have an ESR meter, and to Aquire one would be out of the OP's scope of works. If you have means to solder with the correct tools then it's easier and peace of mind to just replaced the "bulging cap" regardless of measurements. My experience also told me that replacing the "bulging caps " is to be safe than to be sorry, ESPECIALLY UNDER MY WATCH! I had issues of degrading SQ and increasing psu "hum" and electrical inference out of a Stax SRM Mk2. One of the plastic 100uf/400V cap was bulging, upon replacement this cap, it measured 100uf but I don't have the means to measure ESR. Replacing these psu caps resolved my psu hum issue and electrical noise. So if it was my equipment under my watch, I won't let a bulging cap pass!

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I disagree with you on this via my experience. Bulging caps means that they have been stressed out, either the manufacturer has skipped on correct values due to cost savings or supply issues or its just down right age! I have no trust in the "Elna" brand as I saw many of this brand fail in psu that are not even for audio. Not many owners like myself are going to let a "bulging cap" go because it "measures " OK via a ESR meter or a capacitance meter. I don't have an ESR meter, and to Aquire one would be out of the OP's scope of works. If you have means to solder with the correct tools then it's easier and peace of mind to just replaced the "bulging cap" regardless of measurements. My experience also told me that replacing the "bulging caps " is to be safe than to be sorry, ESPECIALLY UNDER MY WATCH! I had issues of degrading SQ and increasing psu "hum" and electrical inference out of a Stax SRM Mk2. One of the plastic 100uf/400V cap was bulging, upon replacement this cap, it measured 100uf but I don't have the means to measure ESR. Replacing these psu caps resolved my psu hum issue and electrical noise. So if it was my equipment under my watch, I won't let a bulging cap pass!

You're missing my point. Again. Most 'bulging caps' aren't. It's just the plastic coating and is of no consequence. Certainly, if the aluminum is bulging or the rubber sealing is distended, then the caps should be replaced.

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You're missing my point. Again. Most 'bulging caps' aren't. It's just the plastic coating and is of no consequence. Certainly, if the aluminum is bulging or the rubber sealing is distended, then the caps should be replaced.

.

Like I said, I don't believe you, I don't have a ESR meter, and if it's my equipment, not on my watch! I won't let a bulging cap go!

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It's quite funny that someone blames a reputed cap as failure prone when they are not the end manufacturer and it is down to the design team of the finished product to ensure the non failure of selected components either through ensuring adequate ventilation, voltage stability, ripple current rating suitability or any number of operation parameters.

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You're missing my point. Again. Most 'bulging caps' aren't. It's just the plastic coating and is of no consequence. Certainly, if the aluminum is bulging or the rubber sealing is distended, then the caps should be replaced.

 

Agreed 100%. I've seen this a number of times and the caps have been fine. Such deformities relate to the outer plastic heatshrink contracting and forcing the plastic disc on the top of the capacitor to bulge. It's not reflective of the cap discharging in any way.

 

It's important to note that large snap-in or screw-terminal FILTER caps generally do not vent through the top of the capacitor. The top of the capacitor is sealed, and venting instead occurs via the rubber base of the cap. Many people wrongly think that large filter caps are top venting, but they are not. Any deformation of the top plastic disc is NOT indicative of a filter cap which has vented. 

 

Your average through-hole caps with the 'T' or 'X' shaped imprint to enable top venting of the capacitor are a different kettle of fish altogether, but this is is not what the OP is referring to.  

 

Here's a nude Panasonic 15000uf 63V 40mm x 50mm cap which shows the solid top perfectly:

 

Panasonic%20caps1_zpsqivysfh1.jpg

 

Panasonic%20caps2_zps4kuzjmvv.jpg

 

Panasonic%20caps3_zpsoyvu7nth.jpg

 

 

 

 

 

EDIT: Ha... guess what... it would appear that the Elna 'For Audio' caps in this particular Denon DO have a 't' shaped relief on the top of the capacitor, and there is no plastic disc covering it. If this is indeed the case, take back what I said above. If the cap has actually vented, you'd obviously replace the sucker.

Edited by pete_mac

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Just double check polarity when installing and it should be fine

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EDIT: I shouldn't have trusted what I saw, according to service manuals they should be 71V rated and marked DENON.... these are likely fakes. Oh well no better time to replace them. Probably don't care so much about the previous questions considering they are readily available now.... Cheers

If you check your service manual, you will likely find words to the following effect: "The manufacturer reserves the right to make improvements as necessary."

Manufacturers regularly change suppliers throughout a production run. However, I would still question the need to change the caps. Has the aluminium deformed or the rubber seals failed? Or just the plastic covering? Deformation of the plastic coating is normal and does not affect the performance of the caps.

Always abide by the tech's code: 'If it ain't broke, don't fix it.'

Edited by Zaphod Beeblebrox

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Agreed 100%. I've seen this a number of times and the caps have been fine. Such deformities relate to the outer plastic heatshrink contracting and forcing the plastic disc on the top of the capacitor to bulge. It's not reflective of the cap discharging in any way.

It's important to note that large snap-in or screw-terminal FILTER caps generally do not vent through the top of the capacitor. The top of the capacitor is sealed, and venting instead occurs via the rubber base of the cap. Many people wrongly think that large filter caps are top venting, but they are not. Any deformation of the top plastic disc is NOT indicative of a filter cap which has vented.

Your average through-hole caps with the 'T' or 'X' shaped imprint to enable top venting of the capacitor are a different kettle of fish altogether, but this is is not what the OP is referring to.

Here's a nude Panasonic 15000uf 63V 40mm x 50mm cap which shows the solid top perfectly:

Panasonic%20caps1_zpsqivysfh1.jpg

Panasonic%20caps2_zps4kuzjmvv.jpg

Panasonic%20caps3_zpsoyvu7nth.jpg

EDIT: Ha... guess what... it would appear that the Elna 'For Audio' caps in this particular Denon DO have a 't' shaped relief on the top of the capacitor, and there is no plastic disc covering it. If this is indeed the case, take back what I said above. If the cap has actually vented, you'd obviously replace the sucker.

I wouldn't replaced those Panasonic caps from your pics, they look fined. But looking "fine" can be deceiving.

Have a look at this thread:

http://www.stereo.net.au/forums/index.php/topic/48986-stax-srm1-mk2-new-lease-of-life/

One of those CEW 100uf/400 is faulty, from the pics I took, it looks fine. Taking it out of the circuit PCB the vents haven't been effected all look OK, they also measure fine as you can see from the fluke; 99uf. Unfortunately I'm not able to measure the ESR.

One thing that's not clear here is that one of those caps is slightly bulging out and the top plastic cover is Matt finished compared to the other 2 that's gloss finish. edited: if you look it's the cap on the corner, you can see it's not as shinny as the other 2 towards the center.

However, the SQ is effected with a severe hum and slight static of memory. This unit is over 30yrs old! The SS devices and the resistors all look fine. Replacing all the electrolytic caps and the hum cycle and static disappeared, which is what I expected! No big surprise here! Measurable buy ear!

Just because a component looks fine doesn't mean it is fine especially when you have a fault, assuming that it is fine is one big mistake techs make! Yes measurements will determined that, but if you had to remove an electro to measure you might as well replace it.

I've seen failures straight out of the box where series resistors in line with psu go open, and techs wonder why the thing isn't powering up, the resistor looks fine and the components are all brand new so where do you start! I've had solid state devices go open as well, they look fine, and no sign of burn marks but place a meter across it and it's a open circuit.

Edited by Addicted to music

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Deleted post

Edited by Addicted to music

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Deleted post

Always learning and won't stop now but the my friend thing was scary. Well outside the range of normal behaviour even for you. Thankfully email notifications still hold the initial pre edit content, I feel all warm and fuzzy.

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