Need help replacing a Rifa X2 capacitor.

[klugardo]

I have a blown Rifa X2.

It reads

PME 285 MB
40/11/56/b

on the other side

275v~SH

on the top

68n N3

What can I replace this with? It's discontinued. All I can find online
is 100u M4 and i dont know what any of it means.

Thanks.

[BulgingCap]

You should be able to salvage something similar out of a huge range of scrap electronic units, domestic or otherwise. There will be something useful around the mains input part of the PCB. It may not be RIFA but will have 'X2' written on it somewhere. 275V is important but any capacitance value near to 68 nanofarads, such as 100n will be fine.
BC

[Maarten]

If you salvage anything, make sure it's NOT a paper capacitor as they will do the same shortly, especially if used or old stock. Other X2 capacitors also deteriorate, but only with use and much slower and usually with a nicer failure mode.

It would be best to get a nice new X2 (X2 implies 275VAC or higher, 250VAC is old stock or cheap stuff) MKP (MKP means polypropylene dielectric instead of paper) capacitor of a reputable brand(Vishay, Epcos, Wima, Panasonic). In most cases 100n would be perfectly fine. If used as a series dropper, it should be replaced with an 68n type only.

[jonnybear]

These would be fine.https://www.ebay.com/itm/Lot-of-10-M...UAAOSwUQ5bvUTV.
john

[klugardo]

OK there is a replacement part here since that Rifa is paper discontinued.

https://www.mouser.com/datasheet/2/2...275-961366.pdf

If it says 68u I would rather replace with 68u, not a 100u

Anyone know why this might have blown and could it have taken any other electronics with it?

Do you know what the 40/110/56b means?

Rated Voltage 275 VAC 50/60 Hz
Capacitance Range 0.001 – 0.6 µF
Capacitance Tolerance ±20%, ±10%, ±5% on request
Temperature Range −40°C to +110°C
Climatic Category 40/110/56
Approvals ENEC, UL, cUL

What is climatic category guys? Is it important?

[klugardo]

0.0068 5.1 10.5 13.5 10.2 21 1,200 P276HL682M275 PME271MA4680M
0.0068 5.2 10.5 18.5 15.2 19 1,200 P276QE682M275 PME271M468M
0.068 7.8 13.5 18.5 15.2 5.6 1,200 P276QP683M275 PME271M568M

which one is 68u

[McMurdo]

No need to over-think the specs here.

The one in your link is another paper capacitor, this will eventually fail.

Better as others have said already is a Metallised Polypropylene Capacitor.

Mouser stock code 98-683MKP275K

68nF 310VAC class X (across the line rated)

[Station X]

Originally Posted by klugardo

0.0068 5.1 10.5 13.5 10.2 21 1,200 P276HL682M275 PME271MA4680M
0.0068 5.2 10.5 18.5 15.2 19 1,200 P276QE682M275 PME271M468M
0.068 7.8 13.5 18.5 15.2 5.6 1,200 P276QP683M275 PME271M568M

which one is 68u

The capacitor required is 68nF (nanofarad).

This is the same as 0.068uF (microfarad).

To convert nF to uF move the decimal point three places to the left.

[Maarten]

On molded or epoxy potted paper capacitors, the climate category (and all other specs and markings) means that it will fail before its time and probably in a violent manner. No other way to say it. Just use an MKP.

[klugardo]

ok so having it rated more at 300 vac is not bad?

it doesn't have to be a 275? are they designed to fail to protect other circuitry?

is the voltage and the fared the only things i should be concerned with?

frequency isnt an issue?

thank you

my issue is.

is it supposed to fail? in a condition where there could be a safety issue (fire-explosion)

is this sort of a fuse or no? this is in a controller board for a 220 cooktop.

ok so the replacement is either
P276QP683M275(1)
or
683MKP275K

now since IT IS called a safety capacitor. are they not supposed to fail?
if this part is replaced with a part that doesn't fail, would it just throw an error on the board instead of blowing?

sorry so many questions guys i am not a circuity person.
i just want my cook top back i love it.

[paulsherwin]

You are over thinking this. X2 capacitors made with a paper dielectric have a common failure mode whereby they fail short circuit and burn up. This is not a deliberate feature but a fault. Plastic film X2 capacitors do not fail in this way.

300V AC or higher is fine.
Frequency is not an issue.

[klugardo]

Ok guys then I will be purchasing this one

683mkp275 the plastic MPK

All the information you have given me is spectacular i appreciate it.

I have a picture of the way the last one went on the board.

I dont see any markings that signify + or -

Any tips.

[Station X]

Originally Posted by klugardo

I don't see any markings that signify + or -

There won't be any polarity markings. These are non-polarised capacitors with an AC voltage across them. You can fit them either way round.

[klugardo]

https://www.mouser.com/datasheet/2/2...71-1104176.pdf

Well this is the part I will be getting guys.

Thanks I'll post what happens after install.

[Station X]

On the first page of the data sheet it says they're not suitable for across the line (mains) applications.

[Maarten]

Or in other words: they aren't X2 capacitors. X2 (or X1 which is also good) is a hard requirement for mains suppressors.

[Station X]

A Mouser stock code was given in post #7.

[klugardo]

well i almost made a mistake.

is there a cap plastic that does across the line and is 68n 275vac?

[McMurdo]

the one I said in Mouser is fine, its rated 'across the line'

[klugardo]

ill send them that this is the one i want in a .068nf 250vac