Vintage caps cross section

[Mico]

So how bad a 35 years old electrolytic cap in average amp PS board could be?
Just replaced 14 caps on Onkyo TX 4500 receiver`s powers supply board with Panasonic FCs and I think I can hear some difference...maybe more precise bass and crispier highs, and seems like I got back a few W of power originally present - maybe. Subjective perception and oscilloscope aside, I decided to rip them open and see what was actually INSIDE. None of the caps showed any physical signs of failure (bulging, sleeve shrinking etc.) and to get some reference I sacrificed one brand new Panasonic FC. Non scientific method was to take the innards out, than just lightly press it against the regular sheet of office paper and see what happens.
I did open all 14 caps but for picture used few random samples from present manufacturers: Marcon (Toshiba brand), Sanyo, Nichicon, Elna and Chemicon. Marcon/Toshiba caps (7) were the biggest surprise, almost as good as brand new Panasonic FC, with a lot of "juice" even on the can walls. Elna and 2 Nichicons were also not bad while one single Chemicon was barely wet and 3 Sanyo caps totally dry! Not an universal rule of course, I have seen badly aged caps from all makes but here I had rare opportunity to take 4 brands from the same heavy duty PS board. This board has three blazing hot transistors on heat sinks and all good caps were actually closer to them than three Sanyo`s...FWIW. I am sure pictures will be much more interesting .

 

[cfinchrist]

I wonder...if drying out is such a problem, or the cause of problems, why couldn't a person poke a tiny hole in an old cap and using a syringe...reload that baby with fresh cap juice? Then seal it with something? Would it be the problem of introducing oxygen? Are my questions moronic?

 

[cfinchrist]

Is there just way too much pressure inside when in use? Are my questions moronic?

 

[Fun2Learn]

Interesting

As you said not strictly scientific but very interesting.

Thank you for taking the time and sharing the results.

 

[Mico]

I wonder...if drying out is such a problem, or the cause of problems, why couldn't a person poke a tiny hole in an old cap and using a syringe...reload that baby with fresh cap juice? Then seal it with something? Would it be the problem of introducing oxygen? Are my questions moronic?

Not an expert here but aside from risking shorting and unpredictable chemical reaction it is much easier and cheaper to simply replace old cap with the new one...

 

[timblade68]

My vote goes to:

new caps = new materials, new chemicals, and the 30+ years of scientific research put into the mix and applied to audio.

as an after thought: compare a television today to one of 30 years ago.

 

[ghamilton]

I replaced all electrolytics in my 919. I took no chances.
The inside of the FC cap looks better built than the others.
I used the FC in my pwr supply & on the amp board.
I used ELNA SELMIC II in the preamp and phono sections.
What a balanced sound!:yes:

 

[BrocLuno]

As you said not strictly scientific but very interesting.

Thank you for taking the time and sharing the results.

Ditto :thmbsp:

 

[Isotonic]

I would be curious to see what one of the sealed orange caps from yesteryear would look like. If moistness is the primary factor, and they retain their moisture as a sealed cap should, then they should sound at least as good as they did when they were new.

 

[SoundOfSound]

I'm wondering if that amp may of been serviced before. I have not seen such a wide variety of different brands of caps in a electronics device before. I have mostly seen only one or two different brands of caps used inside devices that are completely original from the factory.

 

[Baron K Rool]

I've opened several of the orange and light blue "low leakage" caps commonly used in the signal path in vintage amplifiers and in my experience, they are always quite wet. Very good quality seal on those things.

I still replace them when recapping, though.

 

[just dave]

So what is that material inside made of?

 

[Mico]

I'm wondering if that amp may of been serviced before. I have not seen such a wide variety of different brands of caps in a electronics device before. I have mostly seen only one or two different brands of caps used inside devices that are completely original from the factory.

Amp was 100% stock and had very low mileage. All caps were glued, even in blocks of two and three together, had to cut the sleeves to separate some of them...after more than three decades glue hardened like a stone. I think Onkyo had quite diversified parts bin at the time as I see mix of different caps on other boards as well.

I've opened several of the orange and light blue "low leakage" caps commonly used in the signal path in vintage amplifiers and in my experience, they are always quite wet. Very good quality seal on those things.

I was about to open few orange ones next...if that is any indication, Marcon/Toshiba caps were by far the most difficult ones to take out. Very deep and tight seal made of hard rubber.

 

[Isotonic]

In addition to moisture, which I suppose would be a must in a long life capacitor, I wonder if the quality of the electrolytic solution could change.

For example, could the charge or ion content of the electrolyte change and thus change the quality of the capacitor.

I am not particularly strong in my perceptions here so please feel free to correct my expression or misunderstandings.

 

[Mico]

Vintage caps update

So here is my take on the last myth, orange "low leakage" epoxy sealed caps.
I took 6 orange Chemicons from my Marantz 2238B amplifier board - but unlike above mentioned Onkyo TX 4500 receiver this one had quite a mileage.
To have fair electrolyte "footprint" comparison with orange ones I opened one brand new Nichicon PW of similar size and diameter and another two standard black Chemicons from the same Marantz, just to make it more interesting...
I think picture tells the whole story, despite being heavily sealed all orange capacitors were in the pretty bad shape. There was nothing special inside, regular paper/electrolyte stuff and even hermetic seal could not stop it from deterioration and drying. So, let`s replace them all...

 

[Isotonic]

Very interesting images. Thanks for taking the time to do this.

 

[pete_mac]

So here is my take on the last myth, orange "low leak" epoxy sealed caps.
I took 6 orange Chemicons from my Marantz 2238B amplifier board - but unlike above mentioned Onkyo TX 4500 receiver this one had quite a mileage.
To have fair electrolyte "footprint" comparison with orange ones I opened one brand new Nichicon PW of similar size and diameter and another two standard black Chemicons from the same Marantz, just to make it more interesting...
I think picture tells the whole story, despite being heavily sealed all orange capacitors were in the pretty bad shape. There was nothing special inside, regular paper/electrolyte stuff and even hermetic seal could not stop it from deterioration and drying. So, let`s replace them all...

Excellent thread this, and VERY interesting regarding the condition of the orange 'low leakage, low noise' caps.

I might conduct similar surgery on some of the caps I have here so that I can see the differences and the overall condition of the caps in the flesh.

 

[Oilmaster]

Interesting, nice to see pictures.

Do wash your hands well, old caps from the 70's can still contain cancerous PCB.

 

[cableguy2]

I just recapped a Citation Eleven and checked some of the old caps, and they were way out of spec, but the Marcon's were still within spec, but I had already replaced them. Thanks for that look inside.

 

[Mico]

Interesting, nice to see pictures.

Do wash your hands well, old caps from the 70's can still contain cancerous PCB.

Yes, PCB...I had Nitrile protection gloves but despite being odorless electrolyte still managed to irritate my throat. I think new caps were responsible for that, old ones were mostly dry.