Dissect capacitor to see if it's the source of a leak?

It's not a leak. The damn thing is 'worn out' !

Just replace it.

And yes it would have made a hum too.

Graham

"bryanska" wrote in news: snipped-for-privacy@q2g2000cwa.googlegroups.com:

It's not a good idea to dissect electrolytic capactiors. They have nasty chemicals inside them.

It's not a good idea to dissect electrolytic capactiors. They have nasty

Still, if the center is lighter-colored than the outer layers, is this a symptom of a leaky cap?

Gee what is YOUR definition of "nasty chemicals" !!! Sodium Borahydride maybe ? Yukio YANO

Are we talking electrical leakage or physical electrolyte leakage? The brown stuff could be electrolyte, or it could simply be glue used to support the large capacitors.

Yukio YANO wrote in news:FIUth.797812$R63.487719@pd7urf1no:

From Wikipedia entry on Electrolytic capacitors:

Safety

The electrolyte is usually boric acid or sodium borate in aqueous solution together with various sugars or ethylene glycol which are added to retard evaporation.

*** Care should be taken to avoid ingestion of or eye contact with the electrolyte, and any areas of the body where skin contact has occurred should be washed in good time.

*** It is important to follow safe working practice and to use appropriate protective equipment, notably gloves and safety glasses, when working with the electrolyte.

*** Some very old tantalum electrolytics, often called "Wet-slug", contain the more hazardous sulfuric acid, however most of these have corroded away by now.

(emphasis added)

I for one have grown weary of endless warnings inserted in countless replies. Do we need to lecture an adult about taking apart capacitors? Just offer something constructive about his question or stay quiet. Maybe he's a teen, so what, this is mild stuff, not VX. Has anyone here burned their fingers toying with capacitors as kids? Nothing happened when I played with them. And I had enough sense not to rub it in my eyes, and I'll bet if your curious enough to want to take apart a capacitor, your smart enough to not eat the stuff.

These constant warnings are distracting and paternalistic. It makes you look like a helicopter parent, hovering about, quick to swoop in eliminate any and all perceived hazards, but saying little about the question.

As a concession, you can require group users to read a safety warning, "Warning: Advise Offered On This Site May Be Dangerous" Then we can ponder the questions and stop being endlessly irritated. Warning: reading this post make cause extreme mental fusing, if so, seek professional counseling, just don't complain here.

The brown crust was definitely leaked. It was irregular, not completely encircling any of the three capacitors it pooled around, and connected.

Does anyone have any thoughts to my original question? Does lighter-colored paper in the center of the wind indicate a leak?

Are you sure that "crust" is not just the remains of some of that dreadful brown glue that you often find around the bottoms of such caps, originally put there by the board manufacturer to improve the mechanical stability of the caps ?

Arfa

So what's your next safe project ? Sawing the tops off of RF power transistors ... ?? d;~}

Arfa

snipped-for-privacy@hotmail.com wrote in news:1169761239.289133.179680 @s48g2000cws.googlegroups.com:

no, it just indicates a higher degree of reflectivity.

Whether it leaked or not does not particularly matter if it was bad, though the brown crust was likely glue.

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YES.

Ya know what? I am going to post a picture of the damn board, and the capacitor.

OK, on Flickr are several pictures.

Included is the best picture I could take of the board. With the two large caps being new, they mostly covered up the brown crust. It's now barely visible.

Also included are pics of the top and bottom of the cap in question.

"bryanska" wrote in news:1169777565.861550.286390 @v33g2000cwv.googlegroups.com:

Hmm, looks like old glue...

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I have to say that it does to me as well. Remains of leaking electrolyte tends to go crystalline as it dries out, and is usually a very light colour. I repair hifi all day every day, and it is very common to find a brown crust randomly distributed around the bottoms of the caps, and it *is normally* the remains of a particular glue that the manufacturers squirt around, and which is well known in the trade for its deteriorating properties, over a few years. Some varieties of it even become mildly conductive, and can wreak havoc with some high voltage sections of TV sets. Assuming that you are correct however, and it is the remains of leaked electrolyte, you should not have fitted new caps on top of it. Any electrolyte leakage onto a board, should be scrupulously cleaned off first.

Arfa