Is it safe to double the bulky caps ?

[hkivan]

I have 2 820uF 200v teapo caps in my Tt 480W.
I wish to add more on the I/P caps &

(1) Pls advice me on the max. value of the caps
I can installed.

(2) Are there any differences ( especially the inrush current )
to replace the old caps to larger caps or just to solder the new
in parallel to the old ? and also, if the news are different brand.

[larrymoencurly]

Re: Is it safe to double the bulky caps ?

Here's what I've seen in other PSUs of decent quality:

500W Antec SmartPower: 1200uF
350W Fortron (80mm fan): 1000uF
350W Enermax EG365P-VD: 680uF
300W Delta DPS-300BB: 820uF

Is there even room to add caps in parallel on the high voltage side?

[hkivan]

Re: Is it safe to double the bulky caps ?

Yet, because I removed the huge
passive PFC inductor. It just like the
one in the attached pic.
There is some room left now.
I done it before on old psu by soldering wires.
Also, I done transferring my Hedy 350W PSU
to a larger old psu case. Then, I added it with larger
heatsink & replaced the 680uF caps to 820uF,
replaced the fans to LED ball bearing fans.

The caps values you mentioned are their original values.
It is of course safe. For the same circuit, to what value
can I added to ? In my case, the Tt 480W come with 820uf.
Can I make it to 1200uf or even 2000uf ?

[tiresias]

Re: Is it safe to double the bulky caps ?

Hi hkivan

You're in Hong Kong, I believe - so your PSU will be rated for 230vac - ie. those two 200v, 820uF will be in series, giving you a total capacitance of 400v, 410uF.

410uF isn't extremely low, although it is a little less than what one would normally see in a passive PFC PSU rated for 480W. The Enermax 470W "noisetaker" unit, for example, has two 1000uF caps, giving 500uF in total.

In my case, the Tt 480W come with 820uf. Can I make it to 1200uf or even 2000uf ?

I guess 1000 or 1200uf caps shouldn't be a problem, although I wouldn't overdo it - what exactly would you like to achieve, though? Is there a lot of 100Hz ripple on the output you want to eliminate?

[larrymoencurly]

Re: Is it safe to double the bulky caps ?

Can't the current peaks go really high and possibly damage the diode bridge if the capacitance is too large?

A long time ago, there was a brand of PC PSUs called GlitchMaster, designed to maintain stable power even during brownouts lasting as much as one second. Did they simply have extra-large input caps?

[hkivan]

Re: Is it safe to double the bulky caps ?

Hi, Tiresias

I learnt of from some sites that greater capacitances
will smooth out cuurent from the BR.

For Hi Fi amp, they usually have over 10000uF.
Someone says 2000uF for every ampere from I/P BR.
This way will sometimes help the base sound a bit more
solid.

In case of PSU, are there any benefits apart from
eliminating 100Hz ripple ? How to achieve the smoothest
current ?

By the way, do you see Netherlands as the
champion of the World Cup 2006 ? Personally, I
really don't like to see Brazil to take the Cup again
.

[MD Willington]

Re: Is it safe to double the bulky caps ?

Personally, I really don't like to see Brazil to take the Cup again

on the other hand I do so enjoy seeing the female Brazillian fans !!

[larrymoencurly]

Re: Is it safe to double the bulky caps ?

This engineering professor: http://users.ece.gatech.edu/~mleach

has plans for several hi-fi projects, including a very high-quality audio amplifier. He explains what improves sound quality and what doesn't. Apparently larger caps mostly allow more power output but don't improve sound quality noticeably because amplifiers naturally reject lots of power supply hum, and it's enough to just regulate the voltage to the low power section of the amp.

[hkivan]

Re: Is it safe to double the bulky caps ?

Thanks, larrymoencurly.
Are you smile just like that goat ?

I wish I counld take that course if
I don't have to earn a living.

[hkivan]

Re: Is it safe to double the bulky caps ?

There are 7 UTC2030 in my 5.1 speaker system which
give 18w o/p per chips , totally 126W O/P.
The I/P caps are 4 unknow 3300uF 25v 105C caps.
The EI transformer is 40VA 4x12v O/P.
For the price of 300HKD ( ~ 30 euro ) I have no
complain but it is obvious to need more power.

In fact, most of the low end china-made speakers
saves on using larger transformer. In order to make
the chips UTC2030 to its potential, I replaced the transformer
to 2 larger EIs ( from old speakers) and recap
with 4x 4700uF YK Rubycons. ( although UTC2030 is also
an low end amplifier IC, and D1875 or LM1875 does
sound better ) Maybe, I will replace them with 1875s later.

The op amp is YC4558. I do have ne5532 &
JRC4560. But the pcb is so crowded that I don't
feel competent to replace it.

Well, I just want to share my DIY experience.
But I will only done to those low ends for
there are more rooms for improvement.
I wish I could learn of more from different people.