Rifa suppressors to avoid

[Richard]

This is the 2nd one of these I've had go in use and every one I've seen in equipment has already failed. I fitted this only 2 years ago from a pack of 5 from RS. Acrid smoke and the fuse blew a few mins after switch on.

A quick Google shows it's a common problem with this metallised paper type of cap both in cap-only form and the RC network suppressor seen here. I'm amazed they're still being made and sold. No harm done but it may have been different if I'd been leaning over it when switching on after servicing - so be warned.

I checked 2 left in the packet. One is cracked open and it's never even been fitted and the other has the start of a fracture visible. So I made up networks from a 47nF plastic film X2 cap and 100R 2W metal oxide resistor. Space was a bit tight but a bit of creative bending got around that, pics attached.

[Phil Y]

Interesting Richard,

I have recently fitted 2 Rifa suppressors, although they are are the 3 pin (1x & 2y) 3 capacitor type. I will have to keep an eye on them!

Phil.

[Richard]

Ah yes, are they the delta caps in the mains filter Phil? If so they should be easy to keep an eye on. I had mine in for several years and they were no trouble. 20 years and I can understand a cap failing but not 2 years like these others...

[bob orbell]

Very interesting Richard, I too use that very same capacitor in power amp and two PSU's, they have been there for more than 8 years, my mains voltage is also very high, could be you have a **** batch, might be worth bringing this to the attention of RS, they are very good when it comes to customer problems and faulty goods, irrespective of the product price. Bob

[Richard]

Hi Bob, yes I'm a fan of RS too and get much of my stuff there.
I can only relate my own experience which is of several failures going back to 1986 but Google "rifa capacitor failure" and you may be surprised.

[Richard]

A quick follow-up,

Re. Phil and Bob's comments about the mains delta cap; whilst sorting through the box for some bits over the w/e I found the last of my 5 RS 239668 delta caps in it's bag perhaps 10 years old. It's not used and shows no problems visually with a magnifying glass. These are still for sale on RS site.

Checking RS for the 47nF 100R network RS 2067847, it is showing as discontinued and a search of RC networks shows no alternative in that value.