The most stressed capacitor in PSU

[bestsystem]

Sorry for asking a question without a real case.

When I open a gereral PSU(e.g. taiwanese brands), there are dozens of electrolytics, usually some are bulged and some are neat.

I believe that some capacitors are more stressed than others, but where are they?

and what kind of capacitor (hi-pot, low-pot or filtering......) will worn out faster, assuming their quality are similiar?

[PCBONEZ]

Re: The most stressed capacitor in PSU

Probably OP Filters but it heat is a big issue too and where that is will depend on the layout.
.
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[TheLaw]

Re: The most stressed capacitor in PSU

Typically the caps that do the filtering after the switchers because those have quite a bit of ripple and noise due to the nature of switchers. The high voltage caps don't usually see too much abuse. The small coupling caps are typically fine too or those associated with a controller of some sort.

[goodpsusearch]

Re: The most stressed capacitor in PSU

5vsb filter capacitors are usually the first to fail.

[silvergoat]

Re: The most stressed capacitor in PSU

5vsb filter capacitors are usually the first to fail.

An interesting statement considering that is where my old PSU started to fail- coming out of standby it would restart and cycle on and off until I removed all power from it.

Can you elaborate on why? And, would it be a fair idea to replace caps on a brand new PSU to avoid these difficulties later?

[goodpsusearch]

Re: The most stressed capacitor in PSU

The 5V standby filter capacitors work 24/24, even when the computer is shut down.

Besides that, when the computer is not working the fan is not moving inside the power supply, so, depending on the psu design, there is a lot of heat generated from minimum load resistor or the 5vsb diode and those parts are usually placed near the 5vsb caps...

I replace 5vsb caps with good japan made caps and make sure the resistors are not very near to them.

And I always turn completely off the power supply with its on/off switch when the PC is not working.

[kc8adu]

Re: The most stressed capacitor in PSU

+5stby followed by the 400v one in the pfc.then other outputs.
just had to replace one in a seasonic in a htpc here.got a reboot then lots of trash on my hf radio mostly on 75m.
it was a hitachi and it vented long ago.i had recapped the unit but figured that hitachi would be ok.it was for about 3 years.btw the ups is a exide pure sine unit so no stress from it.

[kc8adu]

Re: The most stressed capacitor in PSU

those are fuhjyyu.
better known as fuhkyyu.worst on the planet.

The 5V standby filter capacitors work 24/24, even when the computer is shut down.

Besides that, when the computer is not working the fan is not moving inside the power supply, so, depending on the psu design, there is a lot of heat generated from minimum load resistor or the 5vsb diode and those parts are usually placed near the 5vsb caps...

I replace 5vsb caps with good japan made caps and make sure the resistors are not very near to them.

And I always turn completely off the power supply with its on/off switch when the PC is not working.

[Rulycat]

Re: The most stressed capacitor in PSU

those are fuhjyyu.
better known as fuhkyyu.worst on the planet.

Not as bad as GSC.

[shovenose]

Re: The most stressed capacitor in PSU

They are both very bad :P

[Evil Lurker]

Re: The most stressed capacitor in PSU

Not as bad as GSC.

GSC caps are horrible... but Capxcom gets my vote as worst cap manufacturer nowadays. Then again, fuhjyuu was the manufacturer of the only primary cap I have ever seen to fail in a computer psu...

[Spitz]

Re: The most stressed capacitor in PSU

An interesting statement considering that is where my old PSU started to fail- coming out of standby it would restart and cycle on and off until I removed all power from it.
Can you elaborate on why? And, would it be a fair idea to replace caps on a brand new PSU to avoid these difficulties later?

Another reason is unless you un-plug the power cord, the 5v power is on while many people plug in memory, cards, and cpu's.

[dumpystig]

Re: The most stressed capacitor in PSU

The most stressed capacitor I ever knew had just split from its dielectric.
So sad...

[silvergoat]

Re: The most stressed capacitor in PSU

Another reason is unless you un-plug the power cord, the 5v power is on while many people plug in memory, cards, and cpu's.

I've always been in the habit of unplugging completely before touching the inside of any computer (don't trust it not to be on- guess I've been right).

[PCBONEZ]

Re: The most stressed capacitor in PSU

GSC caps are horrible... but Capxcom gets my vote as worst cap manufacturer nowadays. Then again, fuhjyuu was the manufacturer of the only primary cap I have ever seen to fail in a computer psu...

GSC = Evercon = Sacon.
They -may- be out there with a 4th name by now...
.

[Rulycat]

Re: The most stressed capacitor in PSU

GSC = Evercon = Sacon.
They -may- be out there with a 4th name by now...
.

Or hopefully they've folded.

[Pentium4]

Re: The most stressed capacitor in PSU

GSC caps are horrible... but Capxcom gets my vote as worst cap manufacturer nowadays. Then again, fuhjyuu was the manufacturer of the only primary cap I have ever seen to fail in a computer psu...

I saw an old garbage Logisys, and BOTH of the primary Fuhjyyu's failed...I put that thing where it belonged, in the trash