Electronics > Repair
Where can I find information on an old Rifa capacitor to find modern replacemen?
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Aston01:

--- Quote from: Gyro on July 15, 2024, 04:41:57 pm ---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: X2 X1 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.

--- End quote ---

It 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.
floobydust:
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.
Aston01:

--- Quote from: floobydust on July 15, 2024, 08:21:04 pm ---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.

--- End quote ---

Bernina 830 Record Electronic

Lead spacing = 10.2mm
Original Cap height of body = 10.2mm

The enclosure looks like it has room for up to 14mm of height if there was some reason to go to a taller body.
DavidAlfa:
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.
floobydust:
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/B32621A6103J000/592902
https://www.digikey.com/en/products/detail/kemet/PHE450MA5100JR05/3465857
https://www.digikey.com/en/products/detail/kemet/R75PF21004030J/5731245
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