Replacing primary power cap for shuttle silent X 350watt

[tckoo1411]

Hi all, this is my first post for this forums. I have a shuttle SN25P and i have recap the board with rubycon ZL and MBZ. Now i am moving to the PSU. First I have replaced the 20v 2200uf teapos secondary caps with nichicon HM onces. Then I looked at the primary cap which is a Panny 270uF 400V FM. I am thinking if I should replace it with a higher rating one as it gets pretty hot(I think it's one of the hottest component in the PSU). My config is 2gig ram, opteron 175, one 500wd blue, one 1000wd black and a asus 4770 with plenty USB peripherals. So i am thinking if changing the primary 270uF 400v to 400uF or 680uF will help increase the power output of the PSU? Thanks.

[370forlife]

Re: Replacing primary power cap for shuttle silent X 350watt

The primary cap dosen't have much to do with the total output.

Thats more of a issue with the primary switchers and secondary rectifiers.

[tckoo1411]

Re: Replacing primary power cap for shuttle silent X 350watt

The primary cap dosen't have much to do with the total output.

Thats more of a issue with the primary switchers and secondary rectifiers.

Ok. So Will changing the primary cap do any good to the PSU? Is changing from a 270uF 400v to 400uF 400v ok? Thanks.

[everell]

Re: Replacing primary power cap for shuttle silent X 350watt

I am thinking if I should replace it with a higher rating one as it gets pretty hot(I think it's one of the hottest component in the PSU).

Are you sure it is the capacitor that is getting hot??? Or is it the toroid coil next to the capacitor that is getting hot? Do NOT touch these parts when the power is on, and allow a few minutes for the components to discharge before touching any part inside the power supply.

I would not expect the capacitor is getting hot unless a component near it is getting hot and transferring some of the heat. If the capacitor is getting hot, it needs replacement. I would NOT increase the capacitance from 270 uF, but I would consider upping the voltage from 400 volts to 450 volts, or maybe 500 volts.

Also make sure the replacement capacitor is rated for 105 degrees C (temperature rating). And buy a good brand, like Panasonic, Nichicon, or United Chemicon.

[Dgtech]

Re: Replacing primary power cap for shuttle silent X 350watt

I dont get it. How do you have a join date of 2009 but only 2 posts, these two posts?

Anyways....
I'm concerned about the substance of the question being asked on this post. You are questioning tweaking a component in a primary section of a power supply hoping it will have an effect of boosting processor voltage?? First of all, you will burn out the processor if you acheived what you wished for. Second, the design of the power supply has all of the voltage regulation/limitting in the final stages of the SMPS. Third, I'm just going off of a blind assumption that you are a novice and should not be tweaking designs. Replacing parts and fixing is one thing, tweaking designs gets into the depts of electronics that I would not feel comfortable about someone half ass learning from a post.

[370forlife]

Re: Replacing primary power cap for shuttle silent X 350watt

No he just wants to increase the total amount of amperage the unit can put out to provide a more stable output.

[Dgtech]

Re: Replacing primary power cap for shuttle silent X 350watt

I will back off a little. Just remember if you have 350W and V x I = W, then increasing current will limit voltage and increasing voltage will limit current. Sorry for the Ohms Law theory class.

[tckoo1411]

Re: Replacing primary power cap for shuttle silent X 350watt

Are you sure it is the capacitor that is getting hot??? Or is it the toroid coil next to the capacitor that is getting hot? Do NOT touch these parts when the power is on, and allow a few minutes for the components to discharge before touching any part inside the power supply.

I would not expect the capacitor is getting hot unless a component near it is getting hot and transferring some of the heat. If the capacitor is getting hot, it needs replacement. I would NOT increase the capacitance from 270 uF, but I would consider upping the voltage from 400 volts to 450 volts, or maybe 500 volts.

Also make sure the replacement capacitor is rated for 105 degrees C (temperature rating). And buy a good brand, like Panasonic, Nichicon, or United Chemicon.

Ya, After I have off the comp and open the PSU, I touch around in the PSU and found that the Cap is still hot. Other components are either not that hot or have cooled to a lower temp. So I should increase the voltage rating instead of the capacitance rating?

[tckoo1411]

Re: Replacing primary power cap for shuttle silent X 350watt

No he just wants to increase the total amount of amperage the unit can put out to provide a more stable output.

Thanks for understanding the objective.

[tckoo1411]

Re: Replacing primary power cap for shuttle silent X 350watt

I will back off a little. Just remember if you have 350W and V x I = W, then increasing current will limit voltage and increasing voltage will limit current. Sorry for the Ohms Law theory class.

I understand that, that's y I want to increase the power output. V is fixed. I want to increase the current. I know that it's something to do with the primary switcher rating. But I am not really sure which is the primary switcher in the PSU, so assuming they have oversized the switcher, will increasing the capacitance of the primary cap also increase the power output?

P.S: i am not a electrician by practice, just know some simple electronic stuff. Any comment is appreciated. THanks.

[Per Hansson]

Re: Replacing primary power cap for shuttle silent X 350watt

Is this an Active PFC design with one single primary capacitor or a passive design with two capacitors?
Are you in a 230v or 115v country?

How does the rest of the PSU's build quality look? (Filters etc on the primary side all there?)
Please post pictures if you can

If the primary capacitor is getting hot it means it is being worked hard, by for example poor incoming line voltage, or big harmonics in the line voltage
Also of course the capacitor could be too small for the powersupply, but we would need more details about the powersupply to know that...