Damn, did i just buy 4+ year old electrolytics?

[daz]

I bought new caps for my amp and as i always used to get, i bought F&T. Now i see F&T sold in 2018 and the new company's name (mersen or some such name) is on them. But the ones i bought say F&T. If the company sol in 2018 these must be a absolute minimum of 4 years old and possibly much older. How badly do they age on the shelf compared to in use?

[J M Fahey]

I wouldn´t worry about 4 years or somewhat more.

Now 30 years plus would be a game changer, not here.

[daz]

I assume because the 10 years i often hear cited is no longer valid with today's better build quality/technology?

[Helmholtz]

I bought new caps for my amp and as i always used to get, i bought F&T. Now i see F&T sold in 2018 and the new company's name (mersen or some such name) is on them. But the ones i bought say F&T. If the company sol in 2018 these must be a absolute minimum of 4 years old and possibly much older. How badly do they age on the shelf compared to in use?

According to website the caps still carry the F&T logo.
https://ep-us.mersen.com/products/en...ing/capacitors.

[daz]

According to website the caps still carry the F&T logo.
https://ep-us.mersen.com/products/en...ing/capacitors.

Thats strange. There are pics of them with mersen on them. Heres some on ebay... https://www.ebay.com/itm/28416114616...gaAo4LEALw_wcB

[Chuck H]

It was a long (LONG) time ago, but I use to get Sprague Atom's in packaging off a chip clip at a brick and mortar electronics store in California. Stock was rotated and packing was date marked. Anything over FIVE YEARS old was to be sent back to Sprague or eaten by the retailer, but not sold. So that's a five year shelf life. Also, for what it's worth, I've installed power supply caps from my own stock that I knew were over four years old. There were some minor symptoms of less than good filter caps for a little while but once they'd been charged up and used for a week or two they behaved like new. That build was still working fine with over ten years of hard use in the hands of a gigging harmonica player. He had "borrowed" it and I just never got it back until I moved to the PNW. I dismantled it to build something different but I'll bet it would have kept going for a long while if I'd left it with that guy.

[Helmholtz]

Overstorage tends to increase leakage current. It's typically reversible (if the cap is not too old).
Major ecap manufacturers recommend a re-forming treatment if the cap has been stored (or not used) for more than 2 years.
Re-forming is accomplished by connecting the cap in series with a 1k resistor to rated voltage for at least one hour.
Voltage drop across the resistor shows the decreasing leakage current.

With a tube amp it often suffices to fit the cap and let the amp run on a low wattage (say 40W) lamp limiter for some hours.
Lamp dimming shows progress.

Edit: Forgot to mention that tubes should be pulled. Otherwise the limiter will not allow the cap voltages to get high enough for complete forming.

[Chuck H]

Overstorage tends to increase leakage current. It's typically reversible.
Major ecap manufacturers recommend a re-forming treatment if the cap has been stored (or not used) for more than 2 years.
Re-forming is accomplished by connecting the cap in series with a 1k resistor to rated voltage for at least one hour.
Voltage drop across the resistor shows the decreasing leakage current.

With a tube amp it suffices to fit the cap and let the amp run on a low wattage (say 40W) lamp limiter for some hours.

That's exactly how I've done it a couple of times. On one occasion I was working with a manufacturer and there were some amps still packaged that were decades old. The guy I was working with didn't understand how an unused amp might be prone to any failure but I insisted (the guy I was working with was not an amp tech). He balked so we plugged one in. It hummed and fizzled and went dead inside of two minutes. So then we tried my idea. We brought one up on the lightbulb current limiter and let it do it's thing for several hours. It still hummed a bit and otherwise exhibited symptoms of bad filters but at least we were able to try it out and hear it played. New caps were already on order for all amps involved by this time. I had to recap four amps for our purposes the following morning. And I'll even name drop (because I can ) I got to meet Ronnie Montrose on that venture Super guy. Shitty sad end.

[GoldtoneWorkshop]

I thought the same thing when I got some recently. The caps I've gotten from Mojotone here in NC have been labeled Mersen and the ones from CE Dist are still labeled F&T.

I wonder if theres going to be a change in quality with the new branding? I'm sure we would've heard something by now if there was a major shift, but time will tell. I remember when I first got a batch in of Mersen labeled caps, (not sure if it was 47 or 22uF) that there was a noticeable drop in size from the F&T I still had in stock. Not that that matters at all, but it made me wonder.

[g1]

Are they not putting date codes on them or something?

[Chuck H]

Are they not putting date codes on them or something?

I've never looked into it because I'm lazy and it hasn't been a problem often enough to motivate me but I've read here that there are date codes. They're encrypted though so you don't get a readable date. You have to either know the code or contact the manufacturer.