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Capacitor shelf life question

darrenman

darrenman

Member
I have been doing a lot of reading on AK, and slowly assembling the tools and supplies needed to refurb a Sansui AU-717, and am planning to 'practice' with a Marantz 2230 before the AU-717.

My question is about some capacitors I was very fortunate to come upon... a student at school (I teach metal shop) saw me studying the AU-717 schematic in class one day, and then told me his mom works for an electronics supplier and could get me parts... so, I end up getting the big Nichicon Gold Tune and Super Thru power supply and filter caps for free as 'samples'.

My question has to do with their shelf life without getting a charge... I've had them for 6 months, and because of family and work loads I likely won't get the Marantz going and done for 8 months, and the Sansui hopefully would start in 12 to 16 months from now.

Are these capacitors going to be any good by the time I ask them to sing?
 
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Average shelf life for electrolytic capacitors is ten years but considering what you have are quality caps i'd say more like 10-20 years so they will be fine.
 
Thanks, I thought so.

I worried about them not getting a charge... I have read something on AK here about capacitors needing a charge occasionally to stay 'fresh'. I personally had an ear-opening experience at a friend place during a listening session who shelved an old Sony 'ES' CD player for a few years (unplayed), and we queued it up that night to hear it gradually go from gratingly unpleasant sounding to very nice in the span of ~90 seconds. There was a very obvious change in the sound. I just figured it was due to the capacitors slowly waking up again.
 
The Nichicon Gold Tunes and Super throughs have a rated shelf life of 1000 hours @ 85 degrees celcius according to the spec sheet:

http://www.partsconnexion.com/PDF/e-kg.pdf

In real-world terms (using the rule of double the lifespan for every 10 degree reduction in temperature) this translates to 64000 hours at 25 degrees celcius, which is a tad over 7 years. You'll definitely be fine.

EDIT: interestingly, the current specs from Nichicon (the partsconnexion sheet is out of date) now specify a 'voltage treatment' in their specs following storage:

http://www.nichicon.co.jp/english/products/alm_larg/pict_f.htm
 
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