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Amps and Preamps has standby, but should I turn them completely off?

Hi guys, I know there has been discussions of this and the overall consensus seems to be leaving the Solid State amps / preamps on (or standby). I have a Parasound A51 that runs pretty hot. The heat sinks are hot to touch after running them for 2 hours. Ever since I move them to the 2nd floor (gets hot in the summer), I worry that they'd run too hot so I turn them completely off (by switching off the surge protector) after each use. Note that standby mode doesn't solve the heat issue -- it still generates a significant amount of excess heat. 

My question is:
1. Does turning them off after each use shorten their life?
2. Does turning them off increase the probability of failure?
3. Does the excessive heat damage them in the long run by leaving them on?

I am not too worried about warm up time because I use them 2-3 times a week tops. I just don't want the excess heat on the 2nd floor since it's already much warmer than the 1st floor. 

Thanks!!
angelgz2
kijanki's avatar
kijanki
3,575 posts
 
Czarivey,  will you last 40+ years?

kijanki's avatar
kijanki
3,575 posts
 
Timlub, I'm not sure why keeping them charged stops them from leaking.  Perhaps some capacitors are not properly sealed, to start with, and would eventually leak.  Keeping them on will most likely increase their temperature (since electronics dissipates heat) drying out electrolyte faster, hence thickening it (and reducing capacitors' performance).  Company I work for has a lot of obsolete electrolytic caps in stock,  often 30 years, and I never heard of any of them leaking.  They are unusable, in my opinion, but it is not my decision to toss them out.  Keeping fully charged might extend life of some batteries, but not capacitors AFAIK.  The only negative effect turning electronics off is reduction in breakdown voltage of the aluminum capacitor.  Without voltage electrolyte eats out dielectric - aluminum oxide, reducing breakdown voltage.  Presence of voltage rebuilds dielectric.  We're talking  >5years of keeping gear unpowered.
timlub
1,649 posts
 

Hi kijanki,

     I am only speaking from personal experience and the way my feeble brain see's it.  I've been around a whole bunch of Amps being built and modified in my time and have developed my perceptions. 

When caps are charged and the electrolyte is active within them it somewhat pressurizes the inside of the cap.  This pressure helps maintain the seal along with the electrolyte keeping the seal from drying out.

The problem comes when a cap is powered down and seals weaken.... I have seen caps leak.. or even explode when suddenly powered up. It is for this reason that on very old gear that hasn't been run that we always have brought their voltage up slowly on a variac to reform the caps and to protect the amp. It has been a problem is a few brands.... I believe that Mark Levinson had this problem at one time.  

Again,  this is simply my feeble perception... I'm a speaker guy.

czarivey
4,494 posts
 
Kijanki, 
I doubt if I will.
I doubt if I want!
40+ years from now is probably too long.
kijanki's avatar
kijanki
3,575 posts
 
Timlub, caps unused for very long time, as I mentioned before, loose their rated breakdown voltage, but it takes very long time.  Caps might explode because of this, but often when caps are getting very old and dry the avalanche effect (High ESR=heat, heat=higher ESR), can build-up pressure and explode the cap. 

I'm not sure if charged capacitor has more pressure inside, but I'm pretty sure that warm capacitor does, so it might improve the seal, I agree.  I've seen few capacitors leaking, but it was decades ago when capacitors were not up to current design, materials and production standards.

Also, there were some very poor quality electrolytic caps made in China few years ago exploding in computer power supplies.  I would not be surprised to find them also leaking.  A lot of parts are made in China, including pretty much all ceramic caps and quality is excellent, but some Chinese companies might take shortcuts.  I would feel safe with electrolytic caps as long as the are branded by well known companies.  That way my home state "Illinois Capacitor" (now part of Cornell Dubilier) might have factories in China still being very reputable company.
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