Some Information Regarding PS and 418P Series Capacitors

[Structo]

Recently there has been some confusion regarding the SBE Orange Drop capacitors in the PS and 418P series.
Some have ordered 6PS caps and received 418P caps.

I wrote to SBE and this was their response:


The 418P and PS series 600VDC and lower are all EXACTLY the same thing [film, foil, size, everything except the stamp]!
Some of the higher voltage PS series are the same as the 715P polypropylene
parts.
But I doubt those voltages would be of use to you.

The PS series is a relic from the days when vacuum tube TV’s were repaired by every town’s TV service guys.
It was conceived as a replacement capacitor line that was sold via TV repair parts distributors,
an entirely different sales channel than the OEM distribution intended for new product build.

The line faded out pretty much before Sprague Electric abandoned the plant here in Barre in 1985.

BUT, they were the same 418P parts, so we kept making them when there was demand.

There were some products where the “PS series” inadvertently got designed in, and are still ordered occasionally in OEM qty. from SBE.
Problem being, we’ve had to increase our min order size, and the volume isn’t there on the PS series anymore….
We’d really like to drop the line entirely and get rid of the stamps.

BTW, thicker polyester film as used in these parts is becoming very tough to obtain lately.

The issue is that demand for such thick polyester capacitor film has dropped dramatically.
Most capacitors for high voltage applications are made with Polypropylene film, it has much lower losses, and they are not
temperature and frequency dependent as is polyester.
PP does not absorb moisture and change capacitance value as does polyester.

Above said, within our ability to do so at a profit, we will make whatever parts are in demand.

I hope the above was of some use.

And I do respect that old caps and guitar pickups can get together in nearly impossible to model ways that can sound musical,
and that this behavior is very difficult to measure and more difficult to explain.

[thyx]

We need to find some way to consolidate our demand.

[David Root]

I could go for that, thyx, especially if we could find a large stock of older ones with the outer foil end marking.

I think the 225 and the Mallory PVC types are similar too, both polyester.

[Structo]

What he told me was the problem of sourcing the right Mylar (polyester) for the job as there isn't much of it being made anymore.

[Dugmore]

I could go for that, thyx, especially if we could find a large stock of older ones with the outer foil end marking.

I think the 225 and the Mallory PVC types are similar too, both polyester.

The outer foil marking on those caps was completely random. Years ago I checked a bunch of them with a scope and found that out. Contacted the manufacturer and they confirmed that the caps a printed randomly and the "outer foil marking" has no meaning.