Why this huge cap is so light?

[siliconray]

Got another type of huge cap, even bigger than this one I posted here a few days before. Oddly the blue giant is very light. It's a USA made cap, marked "CAPACITOR TECHNOLOGY", Does any one know about this brand?

 

[Enzo]

With a 1984 date code, maybe its electrolyte has evaporated away.

 

[riccoryder]

Maybe it's like the old NiCd D batteries that had an AA sized cell inside.

 

[siliconray]

I have both the same thoughts before. But it works very well. It didn't explode under 420V DC. My tube amp is totally hum free when use this as power bypass. The speaker is still singing after 20 seconds of turnning of the power switch. Just courious why it's so light.

 

[wrenchone]

The Capacitor Technology computer grade capacitors were always suspiciously light compared to competing brands (Sprague. Mepco, UCC, etc.) of similar pedigree. I can't explain it. Maybe I should succumb to curiosity and peel one open (I have a few) to see what's going on, but I've never felt sufficiently motivated, and anyway, I don't think they're around any more.

 

[Tom Bavis]

As I recall, Cap Tech did not use the typical potting compound in their electrolytics - instead, there was a "spike" in the bottom of the can that kept the capacitor winding in position and conducted heat to the can. Advantage they gave was that these caps could be mounted in any position - others recommended only "terminals up". Reason was that at end of life, cap heating could cause the potting compound to melt and plug the vent (next to terminals). If cap overheats with blocked vent, the can could explode... Philips made similar caps, but crimped the can - odd to see the "dented" cans, but they also work fine.