In Polish measurement equipment it is common to find filters manufactured by
Silesia . The diagram on the chassis allows discussion of each part of this filter - the purpose of the choke at the input is to suppress common mode interference (
common-mode interference ), that is, interference that occurs simultaneously on the L and N wires relative to PE. Two capacitors of type
Y form a low impedance path to earth for high frequency currents. The capacitor type
X is intended to suppress differential interference (
differential-mode ), i.e. that which occurs between the L and N conductors. It acts as a shunt for high-frequency currents, allowing them to flow past the receiver (the rest of the device).
What are the problems with them?
These filters were built using paper capacitors. The filter housing was filled with tar and the whole thing was sealed with epoxy resin. After years, this resin often cracks and moisture gets inside. The capacitors get leakage, so several things can happen. It usually ended up that when plugged in, the filter explodes with a big bang or slowly expands, pelting the inside of the unit with tar. The repair is to remove the filter, which can be replaced with a modern factory design made with film capacitors, or it can simply be cut out, reckoning with a higher level of interference. The tar can be easily removed with either extraction petrol or WD-40.
The story is very similar with RIFA capacitors.
Some say that Surstromming is the worst thing the Swedes have given the world, but my poll winner is these paper capacitors. The EEV Blog forum community often jokes that an extension of the name
RIFA is "
replace if found, always! " The capacitor housing is simply a layer of resin that cracks after years and leakage occurs. I have repaired quite a lot of Tektronix brand measuring equipment by simply replacing the RIFs with good quality polypropylene capacitors
WIMA or
Wurth Electronics .
The problem is not Tektronix's domain - in HP digital oscilloscopes from the 1990s, such capacitors sat in filters integrated into the socket and switch. Worst case - it's hard to get such a filter for anything.
Comments
What do you see as the problem? These were the elements then, and these were used. Every filter from the factory has a data sheet with the most important parameters to help you choose a replacement. [Read more]
The problem I see is that someone could be electrocuted by such a faulty filter. Such components were used then, but today we have 2025 and better capacitors. Let me give you an example from work: we... [Read more]
And what did you expect from such a vintage piece of equipment? That each component would hold its parameters for 50 years? So before measurements, they had to be upgraded to modern components. They... [Read more]
This was a 2013 power supply.... I would expect it to be working normally like this after 12 years when someone has shelled out 20k to buy professional equipment. Surely normal capacitors could have been... [Read more]
And it doesn't have to meet current legal/technical requirements. What matters is that it met them at the time it entered the market. The same applies to electrical installations, for example. Does a... [Read more]
I see that this has not resonated. No standard that I know of allows 10 mA to flow between PE and L. This is already a noticeable current flow. A healthy person should be fine if such a current flows... [Read more]
The current standards are a different matter, the plant standards are "standards internal " and are not of general application in the legal sense of them (the standards). A device that complied with... [Read more]
Regulations and standards aside, let's both agree that if we have a leakage of 10 mA, that's a problem that needs to be fixed? [Read more]
Of course! I don't remember the exact value anymore, but it was a few uA. [Read more]
Slightly more, as according to EN 50699 0.75 mA under normal conditions. [Read more]
As for the topic itself - it was posted in the wrong section in my opinion. There are much more appropriate places on the forum for this type of topics treating typically occurring defects in electronic... [Read more]
Not just the Rifa. Wima MP3 X2 - it blazed like New Year's Eve and smoked up the whole room.It made a mess of the power supply by throwing black stuff all around. Just a malfunction. [Read more]
Rifles commonly used in Revox equipment. Some do not replace them to this day, and write that the device after service..... [Read more]
I recently replaced the Rify in the softstart with new Rify. Good to know :D next time I will give something better [Read more]
A little strange when you consider that RIFA AB ended capacitor production in 1988. And new buyer Finvest Oy rebranded RIFA as Evox Rifa AB in the same year. And finally Evox RIFA in 2007 was acquired... [Read more]
Yes, tme sells as Kemet, but parts come branded Rifa [Read more]
Why did the current electrocute Zdzisio if, as you write, there is PE? Was the installation also faulty? Well yes, old installation and nails instead of fuses. Perhaps to add to the drama there was phase-to-phase... [Read more]
Some people have quite a fantasy or a lack of foundation in the subject they assume. [Read more]
The story is, of course, exaggerated and coloured, inserted for humorous reasons - with a working installation, the differential should work. However, in many older houses I have seen some hmmm odd... [Read more]