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Old 23rd Dec 2016, 3:15 am   #121
Refugee
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Default Re: Another RIFA X2 failure...

The last time my nose was attacked by one of those it was lurking in the vacuum cleaner.
It also made the fire alarm give me an ear ache.
Pooh

I fixed it with a Phillips blue one. They fail open circuit with a little black zit on one end if they are pushed a bit in VGA screen flyback circuits.
The vacuum cleaner is class2 with a 2-core power cable so it will be all right and you can still listen to radio 4 on long wave when it is on if you give the volume a bit of a blast so that you can hear it.
I was cleaning the speaker cloth on a radio at the time and had the camera close by.
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Old 23rd Dec 2016, 7:22 am   #122
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Default Re: Another RIFA X2 failure...

That's not a happy cap. Your really lucky it was in a box, else you'd never get the inside's of the scope clean.

A.
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Old 23rd Dec 2016, 10:25 am   #123
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Default Re: Another RIFA X2 failure...

Vishay one on the way here. I was indeed lucky with the design of the scope.

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The last time my nose was attacked by one of those it was lurking in the vacuum cleaner.
That looks like a Henry! I've got one of them. Now I distrust it!
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Old 23rd Dec 2016, 10:56 am   #124
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Default Re: Another RIFA X2 failure...

Another unhappy RIFA - fortunately caught it before it completely let loose, in a Sansui SR222 MkII record deck.

The deck could be started with the on/off/speed switch, but not stopped - started looking for a faulty switch and found the cap.
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Old 23rd Dec 2016, 11:03 am   #125
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Default Re: Another RIFA X2 failure...

They are otherwise reliable cleaners. Just whip it apart and fit another capacitor.
It took about 20 minutes before I finished sucking the floor in my workshop.
My other half loaned it to a neighbor and it came back with a broken hose. The capacitor is the only real failure.
We have had it since the 1980s.
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Old 23rd Dec 2016, 12:35 pm   #126
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Question Re: Another RIFA X2 failure...

With Christmas on the horizon, last week I brought down from the loft my home-brew sequential lights controller. (This was built many years ago before such things became commercially available.) Plugged in the lights chain; powered it up: O.K., everything works as it is supposed to - and all the bulbs worked! A few minutes later, there was a 'phut' - and copious amount of smoke came out of the ventilation holes in the controller case! Switch off; open case: find that one RIFA cap.(incoming mains filter) in the SMPSU had exploded. When replaced (with a different make), normal service was resumed.

So - could the fact that since this item has a very low 'duty cycle' have any bearing on this failure? Gradual moisture ingress over a period of, say, 11.9 months per year? Some form of very slow chemical reaction taking place in that capacitor?

Al.
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Old 23rd Dec 2016, 12:51 pm   #127
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Default Re: Another RIFA X2 failure...

They go crazed after about 20 years and absorb moisture.
I have seen a photo of a box of NOS examples and every one was crazed. The owner put one on an insulation tester and it read a low enough resistance for it to cook on mains.
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Old 23rd Dec 2016, 1:21 pm   #128
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Thumbs up Re: Another RIFA X2 failure...

Thank you!
Quote: They go crazed after about 20 years.
Now I know what to look for.

Al.
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Old 23rd Dec 2016, 2:22 pm   #129
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Default Re: Another RIFA X2 failure...

I think they're pretty good really. The device this was in had an assembly date of some time in 1981. It was from what I can see the original capacitor. They are designed to absorb large mains transients and seem to do a pretty good job of it. Eventually the number of punch throughs reduces the resistance and BOOM!

I'd probably just cycle them out every decade with new ones anyway. They seem to be consumables.

The bit that has annoyed me most is because the replacement isn't turning up until next week thanks to Christmas, I've just had to clean the oven as I had nothing else to do.
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Old 23rd Dec 2016, 11:40 pm   #130
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Default Re: Another RIFA X2 failure...

Hi Al,
At 5-years ago I was in a developmet group of SmartMeters for a global formation. My co-workers, from another group, has had similar X2 problems with some Siemens types to solve: they didnt do over 10years lifecycle becaus becams some leakages... Im sorry, dont tell the exact type of them...
Another knowed X2-problems are older Schaffner Powerline fillters(Switzerland), ended often with fires..
Karl
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Old 23rd Dec 2016, 11:46 pm   #131
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Default Re: Another RIFA X2 failure...

I've seen one of those line filter modules explode in an old Tek 2400 series. Fortunately a company owned one under warranty!
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Old 24th Dec 2016, 12:02 am   #132
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Default Re: Another RIFA X2 failure...

Hi

Those old cracked-up Rifas are pretty diabolical and should be replaced on site without the slightest hesitation.
Horrible caps!

Regards
Symon.
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Old 24th Dec 2016, 12:14 am   #133
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Default Re: Another RIFA X2 failure...

Schaffner filters of a certain age do that too, probably because they have Rifa caps in them.
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Old 24th Dec 2016, 12:23 am   #134
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Default Re: Another RIFA X2 failure...

Quote:
Originally Posted by Refugee View Post
They go crazed after about 20 years and absorb moisture.
They go crazed a lot quicker than that if they are in sunlight!

I hate them, in fact ALL epoxy Rifas, not just the X and Y caps.

Their electrolytics are good, though.
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Old 24th Dec 2016, 1:16 am   #135
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Default Re: Another RIFA X2 failure...

I've seen that picture before somewhere

Frankly, given that that particular 'scope has a conventional mains transformer, I'm not convinced it's essential to stop hash leaving the PSU (the usual reason for fitting them). So, no worries about operating it until the replacement turns up, IMHO...

Yes, the Schaffner filters do use these...

A few months back, I became the proud owner of an old Philips video waveform monitor. It had been working perfectly at work, but become surplus to requirements. I couldn't bear to see it go in the skip, so home it came.

After about 30 minutes of operation, I noticed the familiar smell... So off went the power, and out it came. I rummaged through my box of filtered IEC inlets, and found not one, but two of the exact type. All with very similar date codes. Now, despite realising the obvious thing here, I decided to fit one anyway. Sure enough, after 15 minutes of operation, the replacement did exactly the same!

A non-filtered inlet is working for now, and I plan to plug the second replacement in to an IEC mains lead (with an insulating boot tie-wrapped over the pins), for no reason apart from seeing how long it lasts!

We've also had several fail in our Tek 24xx-series 'scopes.

How much pain they cause depends on which end of the encapsulation fails first. If you're really lucky, the acrid smoke comes out of the IEC inlet, making a mess of just the plug, rather than the terminal end inside the device. Sadly, Murphy is rarely that kind
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Old 24th Dec 2016, 1:17 am   #136
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Default Re: Another RIFA X2 failure...

I discovered one about to go in a B&O Beomaster 5000 receiver, I'd had the thing running to see if it was basically operational before taking it to bits for a clean, everything was fine, so switched off and took it apart. I found it all cracked and ready to pop! I removed it, and still haven't replaced it!

I'm sure the caps in an old Tandberg reel to reel are Rifa or similar, they are epoxy cased things that have all split open, and one channel sounds fuzzy and naff. Probably time I did something useful with that machine (like sell it... because it gets in the way!).

Regards,
Lloyd.
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Old 24th Dec 2016, 10:59 am   #137
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Default Re: Another RIFA X2 failure...

I forget which caps Quad used, but the two Quad33's I have both had the L-N cap cracked and burnt. This was rather before X, Y etc classification, and I honestly think Quad wired it across the mains switch to suppress clicks getting into the audio circuits, which are all rather close to the mains switch.
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Old 24th Dec 2016, 11:21 am   #138
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Default Re: Another RIFA X2 failure...

Quote:
Originally Posted by mhennessy View Post
I've seen that picture before somewhere
Yes RIFA need multi-faceted shaming. It is quite funny that whilst browsing another forum you find someone with a blown up PM3212 at the same time!

Agree with running it without. I have snipped it out. Replacement arriving today apparently but I suspect that might turn into mid next week. The power supply is a two-parter on those scopes with a linear front end and a switcher on that so you can run it off 28v DC or mains.

I never thought my nose would be such a useful instrument though.
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Old 24th Dec 2016, 12:20 pm   #139
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Default Re: Another RIFA X2 failure...

Quote:
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The power supply is a two-parter on those scopes with a linear front end and a switcher on that so you can run it off 28v DC or mains.
And that's yet another reason why I really love those 'scopes

Most of the examples I've seen are Class II, so earth free. While not intended to float up by any appreciable degree (as there are plenty of exposed metal bits), they are great for when you have an earth loop problem.
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Old 24th Dec 2016, 12:23 pm   #140
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Default Re: Another RIFA X2 failure...

Quote:
Originally Posted by MrBungle View Post
Yes RIFA need multi-faceted shaming. It is quite funny that whilst browsing another forum you find someone with a blown up PM3212 at the same time!
I can't believe they are STILL producing the ruddy things :-

http://uk.rs-online.com/web/p/paper-capacitors/0210617/

When I see one in a PSU I'm repairing it always gets hooked out on sight - and NOT replaced with one of the above (although maybe it would be an out of warranty "nice little earner" in 20 years time if the PSU is still in use)
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