Self-healing MKP X2, small capacity?

[Behemot]

Is there something like self-healing MKP capacitor for small capacities, 150 nF is the one in question? I know the big ones are being made like that, got some Arcotronics 47uF ones.

I have been repairing a few boards from Siemens LMU54, which are controll units for gas furnace. The logic uses the most basic design possible as PSU part - there is just foil capacitor in series using it's reactance to lower voltage which is than rectified and dropped to needed voltage with some regulator.

Problem is, ordinary X2 caps fail within less than a year so I am looking either for better caps or some which can repair the holes from puncturing with high-voltage which is probably the thing which kills them, together with maybe current flowing constantly through them. So a cap designed to withstand that at 230 V AC input.

[budm]

Re: Self-healing MKP X2, small capacity?

I use lots of these PANASONIC ECQUA x/y caps for such power supplies for many years. They are rated at 275VAC. There should be 100~200 Ohms resistor in series with cap also.

[Behemot]

Re: Self-healing MKP X2, small capacity?

OK, a small update, I have read my old article, it is not part of the power supply but it sits on ionisation electrode driving. Anyway, I guess something high-quality as Panasonic may be good for it. Or Rubycon also? I have contact for Rubycon distributor. It is not really easy to get my hands on such stuff here without taking a whole box with thousands of pieces…maye taking a few "samples".

[linuxguru]

Re: Self-healing MKP X2, small capacity?

100 to 220 nF, 275 VAC MKP-X2 caps in 15mm pitch are made by numerous manufacturers - Philips, Wima, Okaya, Arcotronics, etc. You may find some in smaller pitches like 7.5 and 10mm also.

[Behemot]

Re: Self-healing MKP X2, small capacity?

Yeah I know but are they self-healing? That prolonges lifetime quite a lot. Those Arcotronics caps I have are 30000 hours or something like that at 85 °C.

[Behemot]

Re: Self-healing MKP X2, small capacity?

We have tried some Panasonic X1 caps, ECQUG. We'll see next time when those craps will die, how long will it work after replacement…

Interesting is, the first one I have replaced with some old capacitor pulled from input filtration of some dissected device, is still working, over a year now. The other board with cap bought in local shop died in three quarters. So either there is bigger problem and we are just healing symptoms, or they sell so terrible craps in here.