???Pre Amp Service???

I know that there have been threads on this very subject, and I remember some one advising that if a component was coming out of a long period in mothballs it was good practice to use a "variac" (I am not sure about the spelling) between the component and the outlet when turning it on for the first time. I assume that this is like a rheostat of sorts. If I recall, it was suggested that introducing AC to a component that had been sitting for an extended period of time might be better done slowly. And I do not remember if this pertained more to tubed gear than solid state. I believe I remember a comment being made that caps do not like to sit for a long long time not being charged and discharging, as I think it was said that they "dry out" over time.

But it’s too late for that, and apparently you experienced no catastrophic results.

From my own experience: from ’08 to late in ’10 I used my system rarely if at all. In late ’10 I took it down to put a new floor in the LR which was, at the time, my listening room. Late in ’17 I took it out of mothballs and everything worked fine. I have since upgraded all the electronics except for the (tube) amp, but today I am still using that amp that sat dormant for over seven years.  I remember the pre was noisy, but that was a bad tube or tubes and I replaced all of them.

I have another tube amp that had been sitting longer than my main amp, and in ’20 I fired it up when I was troubleshooting a signal cap on the main amp, and it did have a significant hum when I got it going.

I do not know enough about this stuff to say if the hum on the one amp came from sitting for a long time. As far as the bad signal cap in the main amp, I think I know what went wrong there and I do not think it had anything to do with sitting for all those years.

But if you did take your pre to a tech and get it checked and update, it seems to me as if that would be a selling point. At least I would see it as such if I was a buyer.

"if it sits in a box for more than 2 years, it's typical that it will work like a charm for two nights and then disintegrate into ashes"....
 Yea that's  my concern about NOT having it checked before selling..Problem is,can a tech tell if everything is really ok OR are there components I should just go ahead & have changed for new to assure reliability for a future owner?

I just now stuck an edit in there about my pre being noisy when I got it running again due to bad tubes, but that would not have been related to sitting.

Your question would be better answered by someone like @atmasphere ,as all I know how to do is make basic checks with basic meters (like a cap checker) and desolder and solder. I was told that the cap checker I have will not predict the life span remaining on a cap, and even if a cap checked good with my cap checker it didn’t necessarily mean it is a healthy cap. Only that if it checked bad, it was definitely bad. I do not know if a tech would have equipment that was sophisticated enough to verify that.

I’d say that if it is a real nice preamp and on top of that you had the film caps updated that would make it more of an attractive buy for some one. But I don’t buy and sell a lot (as a matter of fact, i don’t sell at all) so I do not know. Maybe get an estimate on that and see what it would run?

I started a thread, myself, inquiring about the life of the large electrolytic caps, and I seem to remember getting the idea that they held up better than film caps and I was okay. I was going to change them in my amp anyway, just because if one let go I felt it would be a nasty mess and they would be a breeze to replace in that amp being as there wouldn’t even be any soldering with screw in terminals, but that was a few years ago and i never got around to it and there have been no issues. That is a 23 year old amp and with the exception of one signal cap, there have been no cap failures.

EDIT:  OOPS!  I read your last post real quickly and I thought it was directed my way, and just now noted that it wasn't.  

When I did not used my art audio preamp and my audio research for 2 yrs . Ussully the volume tend to be affected. Maybe it gets dirty.I will have intermittent sound on both speakers. When I cleaned it, it goes away. Yes I start on turning on for 4 hrs then play the next day for 2 hours. I do in slowly. 

@freediver If the preamp is over 20 years and its been sitting for 3 unused, I would have it checked out. Solid state equipment survives this a bit better than tubes due to the fact that electrolytic capacitors don't like heat (so they don't last as long in tube equipment) but once you get to 30 years the filter capacitors in solid state gear is certainly suspect.

The fact that it seemed to sound OK is a good sign.