EEVblog #1183 - RIFA Madness (Schaffner Repair)

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

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[KeanM]

Dave, doesn't that first switch just change the rise time between 5ns and 10ns?
You seemed to be expecting it to change the pulses between 100ns and 10ns, but I'm sure you mentioned rise time in the previous video and the "Tr" notation seems to allude to that.

Good score by the way. I've been looking to get one of these for a while, but very few show up in Australia, and shipping from overseas is often far too expensive.

[prydin]

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.

[twtube]

In German vintage audio forums, these RIFA caps are known as "Knallfrosch", which translates to firecracker.

[semifavorableuncircle]

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

[BlackEpyon]

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.

[mrnmrn]

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!

[MrDuncl]

In the past couple of years Yamaha have done a product recall on 30 year old amplifiers which were fitted with RIFA smoke bombs. On the same audio forum someone had posted pictures of a RIFA capacitor that had exploded despite having never been fitted into a board. No smoke but the thing had completely split apart.

Stories from me about RIFA capacitors.

1). Hope your vacuum cleaner doesn't have one fitted. With all the air going through you won't see smoke but you will smell it everywhere.

2). If equipment fails check for these. My Mother threw away all the accessories for her expensive sewing machine and asked me to take the machine to the tip thinking the motor had burnt out. Out of curiosity I looked inside and it was a RIFA capacitor next to the motor had released all its smoke.


3). I'm watching this after having a second Philips Oscilloscope release all the magic smoke from one of these.

[Hadcrash]

Hahaha these are such a classic thing to have go bad!I happen to live in the city where they were manufactured and know one of the guys who developed those caps. A fun little side note about them is if you leave them powered on they will basically never go bad, because they were designed with some amount of inefficiency, causing them to run ever so slightly warm and dry themselves out.

[DIY-valvular]

Few months ago I put a comment because I repaired a ye olde Swiss made Meteor winder from mid 70's. Electromechanical motor controller was virtually blown out by those Rifa caps. Now I had another popcornish Rifa caps madness. The victim was an auxiliary SMPS assembled in Mexico inside a mid 90's QUAD IVc MK2 pick and place machine "proudly made in the USA" (cuac!). In this ocassion those common mode filter components don't caused massive destruction, but in our cold humid Buenos Aires winter conditions, became leaky and the nearby Laser aligment controller gone crazy.
So, the moral is: If you see an old Rifa cap, just change it!
By the way. Dave, I liked so much your differntial probe! If my coutry's economy goes better (and my own), I may consider to get a pair of those. My lab colleagues have a devotion for frying oscilloscope probes as if they were gifted them!! :-(((

[poptartmcjelly]

"safety capacitor" and "notorious for failing" don't go together too well.

[Herby-]

You DO need all the chokes and caps to make sure that the pulse you generate on the output doesn't contaminate the rest of your instrumentation. All of those devices ARE really necessary. You really don't want to test ALL your lab equipment, only the one device on the DUT side of things. Fascinating about the caps though.

[EcProjects]

I had 2 of these RIFA caps fail in an old sewing machine.
(The one in the machine went first, after 15 min of use, and after another half hour, the one in the pedal had enough also)

Not a pleasant smell at all!

[mishmasta]

I serviced some Luxman stereo equipment from the late 70s that had similar Rifa caps. None had failed, but it was clear the cases were deteriorating like you demonstrated. Needless to say, I replaced them with some new poly x-types along with all of the original electrolytics, and I'm glad I did!

[billr]

I should have disputed Dave's assumption it was the transformer / choke. I used to rewind motors & transformers... and lacquering and baking them. There's no way the lacquer could re-liquify and drip upon being reheated. Yes, in stripping motors we used to heat up the stator by powering it without the rotor... and that would make the windings easier to pry out after air-chiselling the tops off. The lacquer would become sticky... but never liquidy. Maybe after 6 hours at 400 degrees... But my electronics knowledge is very limited. However in this very narrow example my motor/transformer winding knowledge is more than Dave's!!! Yay!!

[legpetruchka]

Merci beaucoup pour cette vidéo. Je vais changer tous les Rifa de mon TEKTRONIX des années 80. Merci encore et Bonjour de France.

[paulstubbs]

I was going through some old (new) parts I have and I found a largish Rifa cap, never used, but cracked just like the rest. I always thought they swelled up and cracked after many years of service - Not so, actual usage does not seem to matter, just the time from manufacture to now.

Years ago, I worked in a Telstra repair shop (TSG Collingwood) and we had trouble with GEC Terminet printers catching fire, it was eventually tracked down to these Rifa caps in the power supply.
These printers could easily be left to run for days monitoring things, unattended, so if one of these caps smoked up there would be no one there to switch it off before the flames started after all the initial smoke had been let out.

[JimGriffOne]

I just smoked a RIFA. The whole circuit went up in magic smoke.

[dipi]

2:59 That broken cap at the lower left looks like a painting. Pretty colours.
Cheers!

[mjouwbuis]

@10:00 that 820n 500V MKP is certainly not a Y class cap but being across the bridge rectifier it's probably the pre-PFC smoothing cap.

[rimmersbryggeri]

In europe they might be underrated by now also since we have raised the grid voltage. In my sewing machine there were 220v caps and our grid is now 250. I dont know how much that would matter but the new ones are properly rated anyway.