How high does plunger come up if bad? Cornell Dubilier 23000UF

[demoncamber]

How high do the brown plungers come up to let you know they are end of service life?

Cornell Dubilier 23000UF 85V Electrolytic Capacitor DCMX233M085CB2B DCMC

[bestsystem]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

A centimeters maybe, imagine the volume ratio, perhaps there is already some atmospheric air inside during the manufacturing process.


Yours one looks normal

[redwire]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

The "plunger" is not really an indicator of end-of-life, it's just the vent valve and yours look perfectly normal - sticking out above the top cover.
I've had some Mallory parts shrink (in) and others stay sticking out, due to the material but that is black or grey rubber.
I think newer CDE parts are plastic/polymer and not affected so much by moisture.

These are high quality capacitors and I would not replace them out of superstition or emotion, as some do in the Hafler amplifiers.

[demoncamber]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

Hi! According to this white paper document the bung is exactly an indicator showing end of life of a capacitor (provided it doesn't fail to do its job), which I had not known until reading this. It states that the bung will come up with pressure as it reaches end of life. Not much on the net really about this at all. However, these aren't terribly expensive at all to replace, if needed. I did message CDE about this as well to see what they say.

I did do an image search on google to try and compare bung lengths for people selling and what not, what I found was all different results, some completely flush, some recessed and some out as far as mine, and some further. Quite interesting.

The only issue I see on their site is I cannot find any 85vdc caps to replace them with, they seem to only go from 75 to 100.

[demoncamber]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

The "plunger" is not really an indicator of end-of-life, it's just the vent valve and yours look perfectly normal - sticking out above the top cover.
I've had some Mallory parts shrink (in) and others stay sticking out, due to the material but that is black or grey rubber.
I think newer CDE parts are plastic/polymer and not affected so much by moisture.

These are high quality capacitors and I would not replace them out of superstition or emotion, as some do in the Hafler amplifiers.

I totally understand what you mean, I was just thinking, these are from 2001 or so, and they are only about $40 each, to replace with new from CDE, so maybe worth just doing. I should really just measure them with a multi, but still, just as easy to replace them for longevity?

[brethin]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

They look fine, unless you just want to blow some $ for nothing leave them alone.

[demoncamber]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

They look fine, unless you just want to blow some $ for nothing leave them alone.

Well, you guys are making me feel better at least about it lol!

[stj]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

it's a seal, if the cap tries to vent the seal will blow off.
dont replace it.

[momaka]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

I totally understand what you mean, I was just thinking, these are from 2001 or so

20 years isn't that much for large can electrolytic caps. Unlike smaller electrolytic caps with rubber bungs and non-snap-in leads, these do tend to last longer due to better seal.

I say if you don't suspect these caps were abused in any (high temperature extremes, especially heat, for long periods of time in operation or many complete consecutive charge and discharge cycles), then just leave them alone. Also, that vent shouldn't be used as an indicator for end of life. Rather, check the datasheet and see if lists an endurance rating. From there, and given the operating temperature and other conditions, you may be able to roughly estimate how close the cap may be getting to end of life. But then again, 20 years for such large caps isn't that much. A good quality large can cap could probably last twice that... or if not, at least a solid 30 years.

*EDIT*
Looks like these caps are found in the Aragon 2005 THX 5 channel amp you posted about in this thread:
https://www.badcaps.net/forum/showthread.php?t=91700

If yes, don't worry about them at all. Looking at the cooling of that amp and how it's built, I doubt these caps ever saw any heat or abuse of any kind. Even 10-15 years down the road, the should still be OK. Most of the Japanese made amps I've seen from the 70's and 80's still have their original "big can" caps working fine if they're from a good reliable brand.

[demoncamber]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

Wow, that's pretty amazing, thanks for the reply.
CDE got back to me and said the plunger will go as high as the terminals if it were to vent, so it's nowhere near that.

My new question is, this amp has 46000uf being split between 5 amp boards, with the way it's wired it seems right side goes to right one and left side to left.

There's plenty of room to add a couple more caps inside, I'd like to see around 80000 or 90000uf capacitance, if I were to add one or two larger caps and wire them all together, do they all have to match UF ratings or can they be mixed?

CDE also no longer makes 85vdc caps and are suggesting I go with the same UF rating 100vdc, is that advisable? And can I mix 100vdc and 85vdc if I were going to keep original and add two more?

I could just upgrade the original two to larger, but I'd have to rewire everything due to short wire runs, so it would be easier to just add a couple more.

[demoncamber]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

*as a side question, while playing music on this amp, if I turn off the amp, the music continues to play for about 9 seconds as those massive caps drain. Is that a good sign that I don't need to upgrade the caps capacitance ratings? While this was at a lower level and only 2 channel mode, I'm sure in full 5 channel mode is where it needs those caps the most.

Some more expensive amps have around 80,000uf on this size amp, so I think I could benefit from the upgrade when I stretch her legs.

This indeed is the Aragon amp http://imgur.com/gallery/TrAoRyK

[stj]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

9 seconds is a very good sign.

[demoncamber]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

9 seconds is a very good sign.

ok good because I went and counted and it's actually more like 14 seconds

[momaka]

Re: How high does plunger come up if bad? Cornell Dubilier 23000UF

Some more expensive amps have around 80,000uf on this size amp, so I think I could benefit from the upgrade when I stretch her legs.

Capacity alone is not the only factor here when it comes to power output. The VA rating of the transformer and size of rectifier need to be equally capable to handle a larger capacity and larger power output.

In other words, upgrading the capacitance may not grant you more power (well, not continuous/RMS power anyways, though you might be able to get more "dynamic"/PMPO power... though I don't consider that to be too important.) Moreover, if you add too much capacitance, that will increase the surge current at power up seen by the bridge rectifier and transformer.

Given the build quality of this amplifier, I think everything was designed to be up to a certain spec. So increasing the capacitance alone might not yield any noticeable gains. I mean, if this was a budget Chinese amplifier where corners were cut here and there to save on costs, you can bet they cut on the input capacitance. But with high-end amps, that's rarely the case. So IMO, you should just leave it as is.

There's plenty of room to add a couple more caps inside, I'd like to see around 80000 or 90000uf capacitance, if I were to add one or two larger caps and wire them all together, do they all have to match UF ratings or can they be mixed?

You can mix capacity.

However, if you parallel a capacitor of XXX uF to one of your existing 23000 uF caps, then you should parallel the same capacitance to the other cap. Unbalanced capacitance can lead to different charge rate at power-up, which may (or may not) lead to speaker pops or other unexpected behavior on pre-amp and output stages.

CDE also no longer makes 85vdc caps and are suggesting I go with the same UF rating 100vdc, is that advisable? And can I mix 100vdc and 85vdc if I were going to keep original and add two more?

Yes, you can mix voltages.
The voltage rating on a capacitor simply tells you up to how high a voltage the capacitor can be charged before starting to arc/break down internally. If your amp already has 85V caps, that means the circuit is probably operating at 85V or less. So when you put 100V caps in, for example, they too will charge to the same voltage as the 85V caps, which is perfectly safe.

In short, it's OK to use capacitors with higher voltage rating than the originals. The reverse, however, is NOT OK (well in most cases anyways... though it can be done if you know/measured the maximum voltage the circuit provides to the caps.)