Replace 10uF 400V with 47uF ... is it okay:?

[JonathanAnon]

Washing machine was giving me a lot of problem, would stop half way during the cycle and the lights would start clicking on and off.. So I tested drain pumps and the usual suspects, before pulling out the front electronics.. Here is what I spotted..



Problem is, this is a 400v 10uF cap, and the closest I have is a 400V 47uF cap... And I cant leave this on my kitchen floor in bits until I order the same cap and replace it... I'm thinking it should be okay, anybody have any objections?

[tom66]

Re: Replace 10uF 400V with 47uF ... is it okay:?

Should be fine, if it's the cap immediately after the bridge rectifier.

[JonathanAnon]

Re: Replace 10uF 400V with 47uF ... is it okay:?

Yeah it's the main filter cap on the front control panel (with the buttons for "quick wash", "Rinse", "Start" etc)... My electronics books say that it's okay to replace with close, but I still mentally find it difficult to be comfortable replacing with a different value.

[Khron]

Re: Replace 10uF 400V with 47uF ... is it okay:?

Replace it without worries - it's in a position where the value isn't (that) critical Quite the contrary, "bigger is better" (within reason). 47u should do just fine there. Keep in mind those caps are specified with +/-20% tolerance out of the factory, so...

[Toasty]

Re: Replace 10uF 400V with 47uF ... is it okay:?

If you can pull the datasheet for both caps and compare their ripple handling capacity at 120Hz, that would give a good idea of compatibility. Likely you'll find a 2 or 3 fold increase in ripple handling ability.

T

[bluto]

Re: Replace 10uF 400V with 47uF ... is it okay:?

Also keep in mind that bean counters will often lower the value on such parts and if it still works the go with it. I had one of those DTV converter boxes hooked up to my Tivo that would switch off when ever there was a 1/4 second power outage (grid switch I guess). I bumped up the filter cap a little bit and now it doesn't do that. So better tolerance to power fluctuations is just one advantage of upping the value of the main filter cap.

[JonathanAnon]

Re: Replace 10uF 400V with 47uF ... is it okay:?

I bumped up the filter cap a little bit and now it doesn't do that. So better tolerance to power fluctuations is just one advantage of upping the value of the main filter cap.

I think the only reason I've read for not being able to use a larger value cap is that if you put in a really big cap instead say a 10uF cap, where the purpose of that cap is to work as a charge reservoir, then it may draw too much current away from the load leaving it unable to function.....

I put in the new cap anyway, it was quite substantially bigger in size but manage to fit it safely... And my washing machine doesnt click any more :-) ...

[cheapie]

Re: Replace 10uF 400V with 47uF ... is it okay:?

It looks like the old cap failed quite badly... What brand was it?

[JonathanAnon]

Re: Replace 10uF 400V with 47uF ... is it okay:?

It was an SMG 400V 10uF... very badly failed alright, came up as completely open with my ESR meter.

[Heihachi_73]

Re: Replace 10uF 400V with 47uF ... is it okay:?

Nippon Chemi-con by the looks of it, the small one is NCC as well, going by the writing on the top. Something bad must have happened in there to kill a Chemi-con (it isn't exactly a KZG).

[Wester547]

Re: Replace 10uF 400V with 47uF ... is it okay:?

Nippon Chemi-con by the looks of it, the small one is NCC as well, going by the writing on the top. Something bad must have happened in there to kill a Chemi-con (it isn't exactly a KZG).

Well, note that the SMG series is rated for a load life of 2,000 hours at 85*C (KZG for 2,000 hours at 105*C)... by way of that sort of rating it has an finite life and a 10uF capacitor isn't exactly going to have a high ripple current rating nor a low ESR rating. The fact that it's a 400V capacitor (I think at least) suggests that its duty was not light, either, especially if that washing machine had many hours and power cycles on it (I don't think the PSU in that washing machine has a fan, either, so maybe it did get hot, but I could be wrong). Capacitors rated at 85*C have 1/4th of the life that equivalent capacitors rated at 105*C do.

[JonathanAnon]

Re: Replace 10uF 400V with 47uF ... is it okay:?

It is a second hand washing machine, I bought it from an auction website about two years ago.. It wouldnt have got a huge amount of use here.. That board is for the electronic control panel, so I wouldnt have expected that there were huge loads on it. There was no fan on it.