How long can a electrolytic capacitor last un-used?

Give VTL a call and see what they have to say. With the SN they may be able to provide manufacturing date.

Electrolyte evaporation doesn't depend on whether a cap is charged or not, mostly depends on temperature. After 20 years you're probably due for a re-capping.

Agreed.  They still dry out and will need replacing.  Does it need it now?  Perhaps not, but it will in next couple of years. If she is quiet with no buzzing or humming that is good.  

     An interesting study, on just that topic (shelf life), here:

https://digital.library.unt.edu/ark:/67531/metadc3104/m2/1/high_res_d/thesis.pdf

If she is quiet with no buzzing or humming that is good.  

@grannyring It may well be running with half of its rated capacity though- and at risk of imminent failure. A cap that is 20 years old is at its 'half life' which is my way of saying that about half of them that old are now failing. The remaining ones that are good are not far behind.

@atmasphere Thanks Ralph. This is Mike Moe. Not sure if you remember me locally, but used stop by your shop a bit when I owned your equipment. I.E remember when I had to have My MP1 board clean because Pro Gold was used inside and was migrating over the whole board because of the heat? I respect your knowledge and will not purchase a VTL Siegfried MK1 that has very limited hours on it, but is 20 years old.

@hiendmmoe That was a while ago!


If that's the amp you want, just consider replacing the filter caps. I would offer a price that reflects that repair cost, unless that's baked in already.

@atmasphere Thanks Ralph. I appreciate your offer very much. Since Ward of Audio Research passed away I’ve been wary of buying older equipment due to enormous expensive of servicing and shipping. I’ll definitely keep that in mind. I miss coming over there and shooting the … with you guys. Mike Moe

@hiendmmoe I should have said 'offer to the seller a price for the amp' in my last post. While we usually repair equipment on the side, at this point we are too busy to take in repairs.