I would like to use these in an Amp I am working on,
About a year ago I bought a bunch of supplies from an older gent who was moving out of his house,
These were in the collection of stuff.
I don't have a cap checker and all I know is they are unused and using just a DMM they seem just fine.
All for circuits under 50 VDC.
Thanks
Peter

I see a pre 1980 date code on at least of them. I'd say they were good
quality caps. An ESR and leakage test would be meaningful. But, if they
are approaching the end of their design lifespan and heading into
"sunset", and I'd bet they are close, do you really
want to risk using 40 year old electrolytic caps?

Pete

I wouldn't recommend using them, but some people would. As Pete mentioned, they are already really old for electrolytics. I'd be concerned that one might fail and I would have to go back in a few years or sooner and replace it again. For the ridiculously low price of new, quality brands of low voltage electrolytics like Nichicon and Panasonic, it makes more sense to use new current production parts.

There are also still some surplus dealers having large quantities of similar parts that are quite old in their inventory, whether or not customers buy them and use them is unknown.

These look to be hermeticaly sealed types I see commonly used in HP test equipment.
If they were mine I would not hesitate to use them. Very high quality.

Corby

I have used some of these. Passed the ESR test, value test and extended leakage test at rated voltage.

The ones on the left look like tantalums to me. They'll be fine. The 30D aluminum electrolytics are rated for relatively long life.

Wouldn't trust 'em if pointed at my eye.

Almost a similar story, I have a pile of lytics from an estate. NOS but old. I keep them around and reform them when I don't have something newer and need to get something up/running. If they reform ok, with minimal leakage, I'll use them in a pinch. It's really hit/miss. This saves me from running out to get new ones (really placing an order w/Mouser). OTOH - If I've planned a restore project , I prefer - as suggested previously, to order new parts since they are earlier in their lifecycle and less risk.

I would not, however, consider using them unless they were reformed. Do you have a variable power supply and means to measure leakage?

I have no way to reform or to really test other than a Variable power supply and I have some diodes about to make DC if needed,
Kinda need them for a project and I really don't want to wait a week to get the little values,
I will see if I can get some local tomorrow.
And yes, Ones on left sealed, Looking like oil filled somehow, Very nice looking units.
Peter

Yes small ones Sprague and the one end is an aluminum cap the other has some epoxy looking like real goos JB Weld.
Going to try and see if I can find some small ones locally.
Peter

I don't think you mentioned what kind of amp you are hoping to use these in. If it's a guitar amp then it may be useful to know that the guitar strings are connected to the amp's chassis ground, and thus to the guitar player unless (s)he's using some sort of wireless hookup to the amp.
-DS

The ones on the left look too big for tantalum especially for the 25uF I can see. The old ones kicking around here are about a third that size.

Carl

Peter,

The cap seen at the lower left in the picture may look big, but it is in reality only 0.312 dia by 0.796 in. long, according to the Vishay 109D Series data sheet. These are still manufactured. Wet tantalum. Elastomer seal.

They can be had for only $34.00 each, but don't seem to be in stock. Likely these are actually made in USA. They were only about six bucks each, back in 1985 ( qty 1 ). The seals are of very high quality, but some of these may still dry-up, just like aluminum parts.

The three other caps on the left appear to be tantalum parts, in a hermetically sealed case. The seal is glass to metal. Could be wet or dry type, in this case. They resemble Vishay Sprague 150D / 151D / 152D style parts.

I don't think that any of the tantalum parts here have epoxy seals. All such tantalum capacitors are called "electrolytic", whether they are wet or dry.

You should be very careful in the application of dry tantalum parts. The dielectric does not heal; they usually fail shorted. Keep them away from voltages beyond their ratings. It is best to have some impedance between the cap and any high current source. Perhaps a fuse.

The 30D parts on the right are regular aluminum electrolytics, with the optional epoxy over-seal. The extra seal was intended to keep cleaning solvents from infiltrating past the rubber seal and causing the aluminum electrode to corrode. I have some of these around with IBM part numbers on them.

It is still a good policy to avoid wetting the seal on an aluminum electrolytic with any chlorine-based solvent. This failure mode is usually very slow; the contamination cannot be detected by non-destructive testing.

Would I use these old parts? Well, on a prototype / breadboard, or for some gizmo that can fail without causing much pain, sure. Not for routine replacement work in equipment that is supposed to keep on working.

Ted

OK, I guess I won't be using them in this project, I want tho project to go well and never have to go back in again,
Most likely the Amp will be looking for a new home in a month or so,,,
After I get a few days of run time out if it that is,
Thanks all,
I may use the caps posted above in projects what will be staying here,
Peter