Higher voltage and lower ESR Cap replacement

[jean-paul]

Passive cooling is OK but a fan in audio ?!?! I would not have that in my house I can tell. Taller feet at the bottom is a good one, that helps.


Templetec, I would also make a calculation what the total price pf replacement caps and machining ventilation slots will cost. Maybe it is a wiser choice to replace it for something that has less caps and is more durable. It reminds me of Marantz SC80. Always defective, always almost all caps gone and always PCB damage. I refuse to even look at them.

 

[trobbins]

When you identify a few capacitors of appropriate capacitance, voltage, 105C rating, and diameter then I'd recommend you look at the datasheet of each cap, as there is more detail that can influence a decision, including the rated ripple current, and the rated service life (in thousands of hours).

Some datasheets show differences in service life of 2-3x longer life. If you had two caps with all ratings the same except ripple current, then choose the cap with higher ripple current.

Imho I would not use ESR as a key criteria - that is a parameter that can be easily mis-interpreted.

The heatsinks actually appear to be in contact with the top plate of the unit.

It doesn't look like that in the following linked photo.
Audiolab 8200CD 換Telos 1.6A / 2CM保險絲 | 笙凱 | Flickr

Lelon don't show an "RXY" range of radial caps on their website (??).

 

[templetec]

Low ESR, long life, 105 degrees.... FM is cheaper and as you have to replace many ...If you want it to keep functioning both FC and FM are fine. I would have ventilation slots milled in the upper cover of the device. Possibly also in the bottom cover for proper convection. At the right side where the metal studs are you could drill 10 mm holes yourself with a sharp drill, drill press and a running vacuum cleaner.

Lelon was THE brand at the "cap scandal" but supposedly they would have improved their products after that.

Thanks Jean Paul and everyone else here who piped in... all good advice. I'll spec some quality caps and find a quiet way to attach a fan. Hopefully I can address these issues once and for all.

 

[templetec]

When you identify a few capacitors of appropriate capacitance, voltage, 105C rating, and diameter then I'd recommend you look at the datasheet of each cap, as there is more detail that can influence a decision, including the rated ripple current, and the rated service life (in thousands of hours).

Some datasheets show differences in service life of 2-3x longer life. If you had two caps with all ratings the same except ripple current, then choose the cap with higher ripple current.

Imho I would not use ESR as a key criteria - that is a parameter that can be easily mis-interpreted.


Thanks Trobbins. I had been looking at service lives and noted they ranged from about 1000hrs at 105C to 10,000hrs at 105C! I'll go with a slightly higher temperature and as long a life as I can find. I didn't know the high ripple current was a more reliable factor than low ESR; thought they were sort of inverse to each other (low ESR = high ripple current) so...thanks for that. I'll see what I can find on digikey Canada. They have really good spec sheets so it's easy to compare parameters.



It doesn't look like that in the following linked photo.
Audiolab 8200CD 換Telos 1.6A / 2CM保險絲 | 笙凱 | Flickr

Lelon don't show an "RXY" range of radial caps on their website (??).

 

[templetec]

Passive cooling is OK but a fan in audio ?!?! I would not have that in my house I can tell. Taller feet at the bottom is a good one, that helps.


Templetec, I would also make a calculation what the total price pf replacement caps and machining ventilation slots will cost. Maybe it is a wiser choice to replace it for something that has less caps and is more durable. It reminds me of Marantz SC80. Always defective, always almost all caps gone and always PCB damage. I refuse to even look at them.

Okay no fan...that's a relief actually. Had a Gallo sub amp on my Gallo reference 3.1 and the fan in that thing drove me nuts! Too hot to tuck in a cabinet so just got rid of it. I'll lift it up with some bearing isolators and drill more holes. Should help...

 

[jean-paul]

A fan really does not belong in audio devices. If it needs a fan it has been designed wrong (which still is somewhat valid in this case)

Make sure you strip the device as much as you can from sensitive parts. Use a drill press and draw the points where holes need to come beforehand and use a center to define the holes. Use tape to avoid drill debris to damage the material surface.Try to avoid spots where active mains voltage is. Deburr the new holes either with a larger drill or with a special deburrer. If the sheet material is iron/steel please use some silver paint to avoid rust. There is enough space for cooling holes just right of the power transformer and right of the main PCB, both will only work OK if there are also ventilation slots in the upper cover. If there are ventilation slots already they will probably be enough when you add the holes in the bottom. Do not make the mistake by drilling the bottom cover with all the stuff still in it. Since you will be ordering new caps you will need to remove the main PCB anyway, also remove the mechanism! Clean the case afterwards and use isopropyl alcohol to remove fingerprints (which also result in corrosion).

edit: just noticed the Audiolab 8200CDQ already has ventilation slots in the back cover. These do not work without any holes for fresh air. I think you only need to add 10 x 8 mm holes in the bottom at both the left and the right side of the main PCB.

Dynavox make some pretty and good functioning feet for audio devices. They are available in various sizes. I use the smallest 20 x 10 mm as standard feet for audio devices and they are excellent.

Lautsprecher Technik - Dynavox Anodized Aluminum Covered Case Feet Set of 4 Silver

 

[templetec]

A fan really does not belong in audio devices. If it needs a fan it has been designed wrong (which still is somewhat valid in this case)

Make sure you strip the device as much as you can from sensitive parts. Use a drill press and draw the points where holes need to come beforehand and use a center to define the holes. Use tape to avoid drill debris to damage the material surface.Try to avoid spots where active mains voltage is. Deburr the new holes either with a larger drill or with a special deburrer. If the sheet material is iron/steel please use some silver paint to avoid rust. There is enough space for cooling holes just right of the power transformer and right of the main PCB, both will only work OK if there are also ventilation slots in the upper cover. If there are ventilation slots already they will probably be enough when you add the holes in the bottom. Do not make the mistake by drilling the bottom cover with all the stuff still in it. Since you will be ordering new caps you will need to remove the main PCB anyway, also remove the mechanism!

edit: just noticed the Audiolab 8200CDQ already has ventilation slots in the back cover. These do not work without any holes for fresh air. I think you only need to add 10 x 8 mm holes in the bottom at both the left and the right side of the main PCB.

Dynavox make some pretty and good functioning feet for audio devices. They are available in various sizes. I use the smallest 20 x 10 mm as standard feet for audio devices and they are excellent.

Lautsprecher Technik - Dynavox Anodized Aluminum Covered Case Feet Set of 4 Silver

Thanks jean-paul. I have a good drill press. I'll strip out the chassis before drilling. I'll post back here when I'm done.

 

[jean-paul]

Yes, please no "best effort' but "best quality" as you really like the device it seems. Also use soft cloth when working on the device. Unnecessary scratches and damage are easily avoided.

 

[templetec]

Can I ask you guys your opinion on which Caps would be best for this application. I've shortlisted 2 types for each of the 2 values.

In the unit now:

Lelon 25V 4700uF 3000hrs@105C 16X40 Ripple(100KHz) 4080
Lelon 16V 6800uF 3000hrs@105C 16X40 Ripple(100KHz) 4080


Option 1:

Nichicon UBY 35V 4700uF 3000hrs@135C 16X35.5 Ripple(100KHz) 6070 (@125C)
Nichicon UBY 25V 6200uF 3000hrs@135C 16X31.5 Ripple(100KHz) 5480 (@125C)

*(note it's 6200uF not 6800uF as per the original value)


Option 2:

Nippon C-C KYB 35V 4700uF 10,000hrs@105C 16X40 Ripple(100KHz) 4220 (@105C)
Nippon C-C KYB 25V 6800uF 10,000hrs@105C 16X40 Ripple(100KHz) 4220 (@105C)

Links to spec sheets:


Nichicon

https://www.nichicon.co.jp/english/products/pdfs/UBY_e.pdf

Nippon Chemi Con


http://www.chemi-con.co.jp/cgi-bin/CAT_DB/SEARCH/cat_db_al.cgi?e=e&j=p&pdfname=kyb


Thanks in advance!

 

[jean-paul]

Only you can tell how warm the device really gets. If you apply ventilations slots you might not need extreme high temperature specced caps....

It does not make much of a difference if the caps will be let's say 55 degrees while specced for either 105 or 135 degrees. Maybe having 135 degree specced caps has negative side impact, no one except you can tell afterwards. Better focus on the root cause of the heat and solve the problem at the root. If you can get temperature down by 10 degrees you have done a very good job. We can agree that the device has a design error as there is development of heat (by design!!!) but no inlets for cooling air. Having only exhausts means the device has no adequate air flow. No adequate air flow means possible overheating and at least impact on longevity of which you already have proof of. It did not help that the company chose for Lelon stuff.

So the first solution is to have adequate air flow and then measure temp again. It might be that it solves the issues by a large percentage or even completely. Second solution his to use quality parts that can withstand the measured temperature. Third solution is the hardest: try to eliminate the heat creating design choices. This can be either very hard or simply impossible. At least have a look at schematics. When for instance class A is used everywhere there will always be heat buildup no matter what. But if for instance the headphone section generates a lot of heat AND it is always on even when you don't use it you might opt for it being switched off when not in use. That will save energy and generates less heat.

Just as an example: I have seen devices with heat buildup as old fashioned regulators like 78/79xx or LM317 were chosen and therefor higher voltage transformers were used. Switching to low noise LDO's and lower voltage transformers solved the heat buildup of the excess voltage converted to useless heat. Or using a 7805 somewhere connected to a 15V supply line @ 0.5A load. A small toroid with a small LT3042 board will save quite a few Watts of heat there.

Never go smaller in value! Try to find lowest cap with same diameter. You need convection for cooling so preferably no obstacles. Best air flow means a gain in getting rid of heat.
Best advice is to measure temp and maybe use extreme high temperature specced caps only for those caps that really cook. As said before, you can't go wrong with Pana FC/FM for the other caps.

 

[basi]

I dont like the Panasonic FM.Find them a bit harsh in the midrange in all my designs.FC are very good,go with them.

 

[templetec]

Only you can tell how warm the device really gets. If you apply ventilations slots you might not need extreme high temperature specced caps....

It does not make much of a difference if the caps will be let's say 55 degrees while specced for either 105 or 135 degrees. Maybe having 135 degree specced caps has negative side impact, no one except you can tell afterwards. Better focus on the root cause of the heat and solve the problem at the root. If you can get temperature down by 10 degrees you have done a very good job. We can agree that the device has a design error as there is development of heat (by design!!!) but no inlets for cooling air. Having only exhausts means the device has no adequate air flow. No adequate air flow means possible overheating and at least impact on longevity of which you already have proof of. It did not help that the company chose for Lelon stuff.

So the first solution is to have adequate air flow and then measure temp again. It might be that it solves the issues by a large percentage or even completely. Second solution his to use quality parts that can withstand the measured temperature. Third solution is the hardest: try to eliminate the heat creating design choices. This can be either very hard or simply impossible. At least have a look at schematics. When for instance class A is used everywhere there will always be heat buildup no matter what. But if for instance the headphone section generates a lot of heat AND it is always on even when you don't use it you might opt for it being switched off when not in use. That will save energy and generates less heat.

Just as an example: I have seen devices with heat buildup as old fashioned regulators like 78/79xx or LM317 were chosen and therefor higher voltage transformers were used. Switching to low noise LDO's and lower voltage transformers solved the heat buildup of the excess voltage converted to useless heat. Or using a 7805 somewhere connected to a 15V supply line @ 0.5A load. A small toroid with a small LT3042 board will save quite a few Watts of heat there.

Never go smaller in value! Try to find lowest cap with same diameter. You need convection for cooling so preferably no obstacles. Best air flow means a gain in getting rid of heat.
Best advice is to measure temp and maybe use extreme high temperature specced caps only for those caps that really cook. As said before, you can't go wrong with Pana FC/FM for the other caps.

I understood that going with a larger than spec'd cap can cause problems down stream...overload other components. That if you can't find the exact same capacitance cap then err on the side of caution and go smaller. I would go for the Nichicon here as it's got the high temp and fantastic ripple current but feel uneasy about putting a 6200uF or 7500uF cap in place of a 6800uF. I looked at the Panasonic caps you recommended and felt they didn't compare in spec's to the 2 above.... at least in terms of hours and ripple current and also didn't fit: the 25V 4700uF is 18mm diameter. I'm going to go with the Nippon CC and open up the cabinet for better air flow. Thought I could just drill out all the holes on top with a slightly larger bit effectively doubling the volume without much aesthetic alteration. I'll add more holes underneath as the ones that are there are directly under the board and don't ventilate the power supply caps as well as they should. Lastly I'm going to get rid of my PS Audio conditioner and buy an APC Audio UPS. I need something that protects against brown-outs as well as surges as I live in the country and our power is very unstable. Those caps may well have died from all the crazy power fluctuations we get around here....

 

[trobbins]

... but feel uneasy about putting a 6200uF or 7500uF cap in place of a 6800uF.

Electrolytic caps typically have a wide tolerance on capacitance value. The UBY is +/-20%, so "6,800uF" could be from 5,400uF to 8,200uF, so your uneasiness is not founded for any standard value near to the original.

... Lastly I'm going to get rid of my PS Audio conditioner and buy an APC Audio UPS. I need something that protects against brown-outs as well as surges as I live in the country and our power is very unstable. Those caps may well have died from all the crazy power fluctuations we get around here....

Unless you know that your amp operates the capacitors at pretty much 100% of voltage rating, then any fears of damaging the caps from mains fluctuations is also likely unfounded. Any electrolytic cap is rated for short duration over-voltage events of +10%. Perhaps if you rented a mains voltage logger, or purchased a cheap plug-in mains watt meter and inspected the ACV often over a week or two then that may better define your risk of damage.

 

[jean-paul]

A small UPS won’t help as these are in bypass most of the time. You would need a double conversion UPS for this goal. Overkill and not a solution to the cause of the defects.

BTW it would help if more details were given. Many here are experienced in engineering but don’t know the details of this specific device. For more efficiënt advice on better cooling it would be ok if you could post pictures of the given situation. Otherwise chances are likely that advice is either hit or miss.

Suggestion: if one lives in the outback it can be beneficial to keep stuff simple. I once helped out in such a situation where all devices were chosen or designed for 12V DC operation with batteries and solar panels. If mains voltage is unreliable and many brownouts and overvoltages occur this can be a worthwhile challenge. Clean DC is a joy for audio but working with distribution of DC is new terrain for most.

 

[templetec]

trobbins, my understanding, which is very limited, is that these circuits are designed with certain upper and lower parameters and the power caps natural variation falls within these parameters. Although the 6800uF cap varies from 5400-8200 a 6200uF varies from 5000-7500 and the 7500uF up to 9000uF. The circuit can handle anything within 5400-8200 but 5000 could be too low and 9000 too high. Not worth the chance when the right values are available. The main issue with the power here is trees falling on the lines in wind storms. It will cause wild swings in power for several seconds before going off completely. The local facebook page is full of people complaining about lost electronics. I have never measured it myself and figured my PS Audio conditioner would do the trick but my neighbor, a retired computer engineer replaced all his surge protectors with APC-UPS after monitoring his power supply over 4 months of winter. He's a stickler for detail so....he must have found some reason to make that investment. jean-paul, the Audiolab was in a cabinet with about 3 inches above it. It will not go back in that cabinet! It's going to be out in the open from now on. I'm not really in the 'outback' ;o). I'm on a gulf island off the coast of Vancouver Island and we get our power from Van Isle. It's pretty reliable but noisy and prone to extreme events and spectacular outages...it's windy. I would love a battery powered system but that'll have to wait until I have more $$.

 

[trobbins]

The main issue with the power here is trees falling on the lines in wind storms. It will cause wild swings in power for several seconds before going off completely. The local facebook page is full of people complaining about lost electronics. I have never measured it myself and figured my PS Audio conditioner would do the trick but my neighbor, a retired computer engineer replaced all his surge protectors with APC-UPS after monitoring his power supply over 4 months of winter. He's a stickler for detail so....he must have found some reason to make that investment.

I recommend you discuss further with your neighbour. For example, he may have access to plenty of ageing IT rack UPS, and may require continuity of supply for his PC and server gear (ie. disturbances from under-voltage on mains) - so perhaps not quite the same application as yours, or the same reason for choosing a particular UPS.

Your application has inherent over-voltage disturbance protection (the capacitors themselves) but only up to a certain duration of over-voltage disturbance. Your applications may well not stress the amplifier caps for a mains surge of +20 to 30%, that would depend on the nominal working voltage of the caps, and their rating.

I'm not saying don't put in measures to reduce the likelihood of problems, I'm just saying fears are fears until you have technically assessed the situation.