Repairing the Schaffner NSD200E Mains Interference Simulator.
And the dangers of bad mains filters capacitors, and RIFA brand in particular.

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Some background: RIFA is Swedish and stands for RadioIndustriernas FabriksAktiebolag, which translates into The Radio Industry’s Manufacturing Incorporated. This was a company launched by the Swedish government during WWII, because it feared there might be a blockade and a shortage on electrical components. The government wanted everyone to have a working radio so they could receive messages in case of an invasion and beyond. RIFA’s initial charter was essentially to manufacture as many components (mainly caps) as quickly as possible. Apparently, the initial runs had some serious quality issues, and a saying in Sweden at that time was “If your radio stops working, just replace the RIFA caps”. Anyway, RIFA became pretty successful over the years and did pretty well. After a while, they started producing ICs and other components as well and eventually got bought by Ericsson to produce mainly ICs for their AXE telephony switches. I worked there in the 80s, right in the transition between RIFA and Ericsson. It was my first job. A summer job that kind of transitioned into a “real” job as a programmer for their test engineering department. It was a great place to work. I don’t think there’s much left of it anymore. The caps production is definitely long gone.

In German vintage audio forums, these RIFA caps are known as “Knallfrosch”, which translates to firecracker.
Lol das is a geile Bezeichnung.
In Dutch: Rifarotjes (also firecrackers with some alliteration thrown in) or rifarookbommen (smoke bombs, also with the alliteration)
Not surprising to me at all when I go bang sure sounds like a firecracker.

Good information on the Rifa capacitors. They were commonly used in older high-end equipment, but I’m not sure if they or their successors are used anymore.
Anyway – I’d say that you now have a decent tool to test any serious build you make.

Same story here. A RIFA cap released its magic smoke in my 30-year old Studer A810 tape recorder. A big puff of white smoke and a strong odor of burned newspaper

Dave, replace the mains input IEC connector as well! It also contains the same type Rifa paper capacitors, according to the comment overlaid on this video. Have a look at that comment now, I asked him, and he confirmed. He tossed out a whole NOS box of these IEC connectors, because they fail the same way!

I agree. The Schaffner IEC connector is almost certain to fail in the same spectacular fashion. I haven’t opened one up but I suspect they have same RIFA caps inside and exhibit the same failure mode.
In my experience the RIFA caps drop to quite a low insulation resistance before failure so an insulation resistance test from line to earth can be useful for finding dodgy Y caps in an IEC module. I treat anything with an insulation resistance of less than 10 megohms as an imminent failure and replace the filter module.
However, finding dodgy X caps with an insulation resistance test from line to neutral is less successful since the filter modules commonly have a in-built discharge of a few megohms which masks the leakage of a failing X cap. It is safest to just immediately replace any Schaffner IEC connectors of that vintage.

This is a common problem with vintage computers. Especially in the power supplies. Just get an old machine, turn it on, and boom! Magic smoke! First thing you gotta do with vintage equipment before you turn it on the first time, is check the caps. You see these paper-wound X/Y caps, you don’t question it, just replace them right away.

I just had the mains input filter go bang on a Tektronix TSG131A video signal generator. Big cloud of acrid smoke too. Made in the mid 90′s. The input filter is in a metal can forming part of the IEC input socket, with the filter caps potted internally. Some people have opened them up and found RIFA style caps. The smoke and resulting smell was terrible, took days to clear!

Might be a good hint to remind people to measure those old safety caps before using them in a new circuit, quite often they slowly fail open and the capacitance rating can be nearly zero after a “one product lifetime” of use.

The PME labeled caps were used extensively in older Tektronix switching power supplies. You must shot gun replace these because they are a ticking time disaster for old gear.

Equipping my second workbench at home, I had three Tektronix Oscilloscopes that I had previously on store spreading fumes in a row just in the span of one or two days!

“safety capacitor” and “notorious for failing” don’t go together too well.

RIFA PME capacitors is pretty much the electronic version of Surströmming.
Both come from Sweden, and both explode and stink.

An old RIFA capacitor blows up while playing a record on Revox B790.

In this video I demonstrate why I ALWAYS replace Rifa capacitors when I am repairing vintage machines.
Do not watch this video if you have a nervous disposition.

Aug 7, 2022 #electronicsrepair #learnelectronics #capacitor
#capacitor #learnelectronics #electronicsrepair In this video I’ll explain the details about safety capacitors, how they are used, X and Y class ratings, and why older RIFA safety capacitors need to be replaced. Tips on component desoldering too.

Anyone who works with older electronic equipment will before long learn to spot Rifa capacitors, a distinctive yellow-translucent component often used in mains filters, that is notorious for failures. It’s commonly thought to be due to their absorbing water, but based upon [Jerry Walker]’s long experience, he’s not so sure about that. Thus he’s taken a large stock of the parts and subjected them to tests in order to get to the bottom of the Rifa question once and for all.

What he was able to gather both from the parts he removed from older equipment and by applying AC and DC voltages to test capacitors, was that those which had been used in DC applications had a much lower likelihood of exhibiting precursors to failure, and also a much longer time before failure when connected to AC mains.

He still recommends replacing them wherever they are found and we’d completely agree with him, but it’s fascinating to have some light shed on these notorious parts.

Rifa Capacitor Fun Follow Up
https://www.youtube.com/watch?v=TB5FL3vziko

One of the main concerns for power electronic engineers regarding capacitors
is to predict their remaining lifetime in order to anticipate costly failures or
system unavailability. This may be achieved using a Weibull statistical law
combined with acceleration factors for the temperature, the voltage, and the
humidity. This paper discusses the different capacitor failure modes and their
effects and consequences

You might think you know how film capacitors fail and degrade in capacitance over time – self-healing due to surges, right? WRONG!
Capacitor expert and AVX Fellow Ron Demcko confirms what’s really going on after a teardown of some failed and one good polypropylene X class capacitor.

00:00 – Teardown of a some failed film capacitors
00:52 – Self Healing and drop in capacitance
01:44 – Capacitance Measurements
02:15 – Teardown of a new Suntan brand polypropylene X2 film capacitor
03:03 – Different failure modes based on size and winding pressure
05:52 – Unwrapping the film
07:51 – The film inside a NEW film capacitor
09:19 – Teardown of the FAILED uTx brand heater capacitor with half capacitance
10:06 – How Schoopage and the end pin terminations work
12:23 – Teardown continues…
12:45 – WOW! What on earth is this?
14:54 – Elecami Wolf also did a teardown
16:05 – Teardown continues…
17:01 – Separating the film showing both slef-healing and extensive metal film corrosion
18:29 – Another uTx brand failed film capacitor from a Corsair PSU, with 90% loss in capacitance!
Elecami Wolf Youtube Channel: https://www.youtube.com/c/ElecamiWolf
19:55 – Let’s call an expert! Ron Demcko from AVX tells us the REAL REASON for the failure!
It’s moisture ingress and corona demetallization!

Full discussion with Ron Demcko:
https://www.youtube.com/watch?v=9V99J22aiLE