Half a volt below rated voltage

[espresso]

Hi
I have this simple audio amplifier incorporating Hi-Fi ic TDA2616 which provides me with 2x12W for my room.

Now, since I'm replacing existing 10W speaker drivers with Visaton's FR10 (20W) I thought I could also replace the old filtering capacitors (from 1999) and replace all small electrolytic caps with WIMA blocks. Plus stronger diodes in Graetz rectifier - RL207 (2A) instead of 1N5398 (1.5A).

The original filtering capacitors were 2x4700 uF/25V (symetrical supply 2x15.5V).
I have just replaced them with 2x 10 000 uf/16V because 25V ones wouldn't fit. As you can see the operating voltage is just half a volt below rated voltage for the capacitors. Will this significantly decrease their endurance? What can I expect?

[Gianni]

Re: Half a volt below rated voltage

Well I don't have the answer about endurance, it depends on several parameters and on the type of cap you are using; give more details like Brand/Type.


The only thing I wouldn't do is to use a cap with a voltage so close to the circuit voltage; I have always seen that a minimum margin is kept is more then 0.5V:

on 5V caps are --> 6.3V/10V
on 12V caps are --> 16V/25V

Just my experience, maybe another member can give more info.

Ciao
Gianni

[arneson]

Re: Half a volt below rated voltage

That is a good simple retrofit
but I would have not jumped that high
and I would have stayed at the rated 25v.
Just my thought,
hope it sounds clean.

[espresso]

Re: Half a volt below rated voltage

Thanks for your answers.
The capacitors are Fujicon brand. I haven't been able to find much info about them on this site but I would rate them as ok from my experience.
TDA 2612 sounds pretty good and I'd say it's ideal for small budget applications like mine.

but I would have not jumped that high

I would also say 4700uF is sufficient but I was curious to see how the amp would behave with double that much. I think this can't hurt besides the voltage issue which I'm not sure about.

[gdement]

Re: Half a volt below rated voltage

16V is only 3.2% above 15.5v. I'd have serious doubts that the tolerances are really that good. Thus they may end up overvolted, but then the caps may also outperform the advertised limit.

[espresso]

Re: Half a volt below rated voltage

They most certainly outperform it in a way that the cap won't explode if put to 40% higher voltage. I've had a 16v capacitor that had been working on 19V for a year (until I decided to save him). I don't know if he liked it because he never showed me he was unconfortable
However my 1.0F gold cap wasn't so lucky cause it died even though the applied voltage was only 0.1V higher than rated (5.6V instead of 5.5V).
Still, I am bothered by the question of quick aging at maximum voltage.

[PCBONEZ]

Re: Half a volt below rated voltage

The max voltage rating is not just nominal voltage it's nominal+ripple.