2 capacitors in parallel vs. single capacitor

[Dannyx]

Good day folks. I need a bit of advice on how I should go about replacing two dead capacitors on a Samsung power board. Wasn't too sure whether this belongs in the TV repair category or capacitor questions, but I settled on the latter thinking it's really a general topic that can apply to various projects, not just power supplies, so here goes:

Without going into too much detail (since that would pertain to the TV section), I need to replace 2 electrolytic capacitors which have failed on the primary of a Samsung power supply. Sounds like a simple task, but the capacitors have an unusual value - 56uF which I couldn't find at my local shop so I was wondering what the best alternative would be. Caps in parallel, as far as I know, add up, meaning I have 112uF there really. Should I go with two capacitors of the nearest higher value (which I THINK is 68uF for a total of 136uF, which is higher than 112uF), or should I go with a SINGLE 120uF capacitor instead, which is closer but still higher ? Of course, they'd be within the 450v requirement of the original ones, so don't bother with that. I don't have any pictures of the board right now, but it's got a PFC booster if that makes the least bit of difference....just in case some tech gurus will immediately point out something really technical related to that which might make either option unfeasible. Cheers guys.

[fester]

Re: 2 capacitors in parallel vs. single capacitor

electolytic capacitors have big toleracne,sometimes 20% and higher capacity is always better :-) so use what you have in hand..

[sam_sam_sam]

Re: 2 capacitors in parallel vs. single capacitor

Can you find a 47 and a 68 UF cap that would very close I have seen this in power supply before

I do not think that it would mater if it is a little over if it this is the main filtering caps
so you could even use 2 68 UF cap as well I would think

[Stefan Payne]

Re: 2 capacitors in parallel vs. single capacitor

In General:
If you only need the capacitance, doesn't matter.
If the cap is highly stressed, more is preferable.

[Dannyx]

Re: 2 capacitors in parallel vs. single capacitor

Can you find a 47 and a 68 UF cap that would very close I have seen this in power supply before

I do not think that it would mater if it is a little over if it this is the main filtering caps
so you could even use 2 68 UF cap as well I would think

I might be able to do that, but wouldn't something bad happen along the way if they're imbalanced like that ? Yeah, you guys are right, main caps like these don't usually undergo a lot of stress (I believe they call that "stress" dv/dt in technical terms ? I may be far off there). These ones only blew because of a power surge, taking some transistors out with them. Varistor didn't go...bad design at its finest IMO >_>

[Dannyx]

Re: 2 capacitors in parallel vs. single capacitor

Tv is now working with two 68uF caps in it Success