Where can I find information on an old Rifa capacitor to find modern replacemen? - Page 1
Forum section: electronics / repair

author: Aston01
author_rank: Newbie
timestamp: July 15, 2024, 04:15:54 pm
content: I am attempting to replace a broken Rifa capacitor but likely due to its age I can't find any documentation on this specific part number (PME 2616 MA 510).Does anyone know where I can go to find enough information to cross-reference to a modern replacement?

author: fzabkar
author_rank: Super Contributor
timestamp: July 15, 2024, 04:33:23 pm
content: https://file.elecfans.com/web1/M00/20/FE/ooYBAFmk4f2AOsh6AFozsxcyW-I075.pdfMP = metallised paperCapacitor Name - PME2616Capacitor Type - General PurposeReplacement Type - PME261E (page 42)

author: David Hess
author_rank: Super Contributor
timestamp: July 15, 2024, 04:33:52 pm
content: MP is metalized paper. Any y-class capacitor with the same capacitance and voltage rating may be used. If it was a line to neutral application, then an x-class capacitor may be used instead.

author: Gyro
author_rank: Super Contributor
timestamp: July 15, 2024, 04:41:57 pm
content: Congratulation on catching it before the Rifa madness set in - they are metalized paper and notorious for giving off lots of magic smoke and occasionally a small flame when they reach a certain age. The cracking allows moisture ingress, which is the ultimate failure mechanism.PME2616 capacitors are still available to this day, now under the Kemet brand, which will normally give several decades of continued life.In most applications, a metalized Polypropylene (MKP) is a suitable replacement. As regards sub-type, the capacitor's position in the circuit is important, so it isn't possible to give an exact recommendation. If the capacitor is being used as an EMC suppression filter in an across-the-mains application, then it is important that a class X type is used, normally an [Edit:X2X1 to match 630V DC rating], as they have thin metalization and are designed to be self healing on voltage spikes. If, on the other hand, it is being used somewhere inside the equipment, on a DC rail or pulse application, then it is important to not pick an X type because a thicker metalization is needed.

author: floobydust
author_rank: Super Contributor
timestamp: July 15, 2024, 05:58:58 pm
content: The Rifa's have oddball lead spacing which makes changing to a better brand, a bit of hassle sometimes.OP you have to know what class, where the cap is- across mains or to GND, used in TRS-80 etc.PME271 datasheetandPME271M510MR30edit: not high enough voltage rating isX2LS=15.2mm but a 15.0mm fits.It's the LS=20.3mm parts that are a hassle to stuff in a modern 22.5mm part.I use Epcos, Wurth, Kemet R46 or R47R474I210050A1Kis X1, 440VAC/1kVDC $0.48 etc. Some Kemet parts have long leads if you need that.

author: wraper
author_rank: Unknown
timestamp: July 15, 2024, 06:09:36 pm
content: Just avoid using any Rifa/Kemet paper capacitors. There is no info they were ever fixed. I know for the fact they were bad for decades, and IME capacitors made in mid 2000s were already failing in mid 2010s. Have not stumbled on these caps made 2010s so cannot definitely say anything about them but why use sus parts when there are so many polypropylene and polyester alternatives.

author: floobydust
author_rank: Super Contributor
timestamp: July 15, 2024, 06:22:24 pm
content: The paper Rifas are for sale even today, and after I'd emailed and gave them (new owner Kemet) shit over the caps failing. Wima obsoleted their version of paper+epoxy.I think they became a magical unicorn part with their use in EMI filtering. No idea what SRF is but this might have helped, or paying to recertify EMI on a product is simply too expensive so use the old part?I wonder what Schaffner is now using in their EMI filters, less smoke please.

author: wraper
author_rank: Unknown
timestamp: July 15, 2024, 06:38:18 pm
content: They are a magical unicorn in a sense that no other caps fail with these audio-visual-olfactory special effects.

author: floobydust
author_rank: Super Contributor
timestamp: July 15, 2024, 07:10:33 pm
content: They are self-impregnating- just sitting there they get prego and bulge and get bigger... leading to epoxy cracking... then... birth of a unicorn does make sparks, smoke, a bit of flame.Paper is still an excellent dielectric in some situations and is used in substation transformers, or guitar amp (paper in oil) capacitors, it can take the oil immersion.

author: David Hess
author_rank: Super Contributor
timestamp: July 15, 2024, 07:17:41 pm
content: There are some X and Y class capacitor requirements that metalized paper capacitors have an easier time meeting.

author: Aston01
author_rank: Newbie
timestamp: July 15, 2024, 07:59:57 pm
content: Quote from: Gyro on July 15, 2024, 04:41:57 pmIt is being used in a sewing machine pedal (wired for US Style 110v). I have tried to find a wiring schematic for the pedal but as of yet no luck.I noticed in other parts of the machine there were X/Y type caps used and explicitly labeled as such but this one has no obvious designation as either type and even the Kemet catalog segregates them into a General Purpose category (screenshot attached).Anyone able to clarify why something not noted as an X/Y type would be replaced with such?BTW - Thanks for all of the information so far... this is an extremely common question for this machine on just about every YouTube video and NO ONE actually identifies the modern replacement.

author: floobydust
author_rank: Super Contributor
timestamp: July 15, 2024, 08:21:04 pm
content: What make/model sewing machine is it? I did draw a few schematics of these, Elna Stella Air? and some other one.What do you measure for lead spacing? The PCB has extra holes to take two different size parts. How much room (height) do you have for one?The part I linked to in post #4 is higher voltage 440VAC X1 and 18*5mm, 11mm H and leadspacing 15mm.edit: it doesn't look like an X-cap application, two high value resistors are in series with it. The EMI filter caps X, Y are in the potted module.The black blob looks like a MOV.

author: Aston01
author_rank: Newbie
timestamp: July 15, 2024, 08:31:55 pm
content: Quote from: floobydust on July 15, 2024, 08:21:04 pmBernina 830 Record ElectronicLead spacing = 10.2mmOriginal Cap height of body = 10.2mmThe enclosure looks like it has room for up to 14mm of height if there was some reason to go to a taller body.

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 15, 2024, 09:24:48 pm
content: You'll find 10nF 630V mkp/mkt (propilene/polyester) capacitors anywhere with the same spacing or close enough.Just search 10nF 630V, anything square with leads will be one of those, usually blue, green, yellow or red.

author: floobydust
author_rank: Super Contributor
timestamp: July 15, 2024, 09:46:10 pm
content: Consider PP 0.01uF ±5% 630VDC LS=10mm, size 13*4mm height 9mm. Not an X-cap application here. It might be doing timing so I'd use a 5% tolerance. This is a common part:https://www.digikey.com/en/products/detail/epcos-tdk-electronics/B32621A6103J000/592902https://www.digikey.com/en/products/detail/kemet/PHE450MA5100JR05/3465857https://www.digikey.com/en/products/detail/kemet/R75PF21004030J/5731245

author: Aston01
author_rank: Newbie
timestamp: August 04, 2024, 04:59:45 pm
content: Quote from: floobydust on July 15, 2024, 09:46:10 pmJust wanted to post a follow-up.I did end up replacing the capacitor withhttps://www.digikey.com/en/products/detail/epcos-tdk-electronics/B32621A6103J000/592902as suggested by floobydust and everything works great now.Thanks again to everyone who helped sort this out.