Failing RIFA Safety Capacitors!

In this video I'll explain the details about safety capacitors, what are they, how they are used, X and Y class ratings, and why older RIFA safety capacitors need to be replaced. How to solder and desoldering tips are shown too.
#capacitor #learnelectronics #electronicsrepair

[JohnnyUtah]

I watch a lot of videos about older electronics, and they often mention RIFA caps in passing but don't elaborate. This was the perfect explanation. Thank you!

[ValuedTeamMember]

Thank you Sir Air-Rick. Your videos are quite engaging... It's like I stopped by to hang out at the bench but was forbidden to speak (lucky you, many have tried:). Glad to hear you give a shout out to Rifa. Like my grandma yells in church and my stepdad says down at the mill; "BINGO! You Nailed it"

[MrWaalkman]

This is the best explanation of safety capacitors that I have seen. Thanks!!

[borisj]

There is no safety involved with these capacitors. They are used to suppress line and SMPS noise. The usual arrangement uses 3 devices, one between the Active and Neutral being around 0.1 uF in conjunction with two others of about 0.002uF wired from the Earth to Active and Neutral respectively. The 0.1uF 250ac device has proven to be most problematic. I had two pieces of HP8563E gear go up in smoke minutes of plugging the equipment into the mains. Have spent their life on 120Vac mains and then being exposed to the 240Vac has resulted in rapid destruction. I replaced them with an ac rated mains capacitors of 275Vac and never had any further trouble. But the word Safety should never be in the same sentence as these type of capacitors.

[Stevie_D]

A good, clear description of what the device is supposed to do, its limitations, and what problem exists with it. I just found your channel in the last few days and I like the subjects and the way you present the material. As a suggestion, you might discuss sources where hard to find parts (like RIFA Safety Caps) can be purchased. Excellent either way !!!

[poormanselectronicsbench]

Dave @ EEvblog recently did a video on "Safety Caps", that, although did not have outward signs of physical damage, but one was used as a voltage dropper to power a low voltage linear DC power supply section of a heater ( "overseas designed") that had failed and caused the control panel on a space heater to quit functioning. After "de-potting" the failed cap, and unwinding the foil, you could see visible signs of internal damage, or, how the capacitor foil was designed to pretty much vaporize at a weak point where the stress of a surge made continuity. Over time, the cap wouldn't short circuit, but it would slowly be out of tolerance as far as capacatance value is concerned. I would probably put these types of components on a list for replacement as far as a maintenance visit inside of an assembly goes, unless you tested them for proper value to tolerance and leakage before calling it good.

[GaryKeepItSimple]

Nice Video, When you refer to 240V it would be nice if USA-specific issues were pointed out. UK has 240 V and we have Live, Neutral and Earth ( chassis) this two-line thing is new to me. Now all I have to do is find a supplier for my VCR safety cap. Cheers.

[MrXenon]

Great video, just one remark: Y-capacitors are often even more safety critical than you described. Nearly every class-II SMPS uses Y-capacitors between the primary and secondary side of the transformer to surpress EMI. If a Y-capacitor fails in a class-I device - like you have shown in your sketch - then usually the failure current is going through PE and the RCI or even the circuit breaker trips. But if a Y-capacitor in a class-II device fails, then you have mains voltage directly on an output that usually is not earthed - e.g. on the output of your smartphone charger. An electric shock is more or less unavoidable in that case.

[brianwood]

Another excellent video, Thanks for sharing Erik. 🎅🎅

[BjornV]

i can be wrong, but in my opinion, Rifa caps start to acttract moisture arround the leads, and once the moisture gets inside, they start to swell, and that swelling cause the cracks in the housing. i experienced many times a bad Rifa cap, and each time when they where cracked, they where also bulged. Never seen a Rifa cap with only cracks without swelling.
A few years ago, i bought some high voltage Electrophoresis powersupplies trough Ebay from USA sellers, where they previous where used on 110/120V, the first time when i received such a powersupply, i opened the powersupply and everything look fine, set the voltage select switch to 230V and power up the powersupply, and after a few seconds, the Rifa cap bursted open in flames.
The entire room smelled for days like burned wood. That Rifa cap was rated for 250V, for use in the USA with 120V, thats fine, but for use here in Belgium or Europe with 230/240V, that is not enough extra headroom. Since that day, i replace every Rifa cap with a Kemet or Wima cap, and choose for a 310V or 400V rating.

[Shmbler]

It's not only RIFAs blowing up though. I've had old 80s WIMA X2 ones (silver color) release phenomenal clouds of white smoke just as well as the RIFAs do. Which makes me wonder: Which brand/model safety caps are actually safe to operate after 40 years?

[johndevires]

Nice informative video.👍 What model is that desoldering tool you use? It seems to work well.

[gunnarMyTube]

7:34 "What the manufacturer did not assume was going to happen"

[agegroot]

I wondered "Are they still needed these days?" Removed a blown one from my Revox B790, didn't replace it.

[TimsWorkshopTJY]

I suspect a failed Dain capacitor is the reason the rv fireplace board quit working. I tested both ends where its leads were soldered in and no continuity? I've read they are not very good. Any suggestions? Thanks

[Diego-lxui]

would you tell where we can buy relaiable safety caps? I know the mouser but other than that...

[crim]

Hi there. X capacitors have + and - poles? Thank you

[vrjb]

Warning for desoldering... that's only needed for countries using the imperial system. Then the desoldering is blocked by hands and filmed of camera.
Vintage equipment without dust?

[gabrielphilips]

How do these capacitors protect the circuit? From what does it protect the circuit?

[y_x]

Do you really need to show how to replace a cap ???