PSU issues

Kostik · Post by **Kostik** » Mon Jun 16, 2003 4:23 am

I have a 250w Fortron PSU (passive PFC, thermistor controled fan, can't remember the exact model but it's similar to this one), and two problems :

- There is a big coil inside the PSU that buzzes and vibrates. I soft-mounted it using rubber pieces and earplugs, and the vibrations don't transmit to the case anymore, but I can still hear the buzz through the acoustic foam.

- The coil began to whine yesterday's night.

Of course i've been searching for a solution through the forum, as I know coil whine and coil buzzing have both been discussed very often here, but I still have a few questions :

1°) I can't find that "special lacquer", that's designed for coils. Is there something else I could use to prevent the coil from whining and that I could find easily ? Nail polish ? Glue ?

2°) Would lacquer/varnish/whatever also prevent it from buzzing/vibrating ? And if not, what could ?

3°) I have a non-PFC PSU at home, and it doesn't have a coil, or at least, not such a big one. Could it be that this coil is related to PFC ? I'm just wondering.

Thanks !

dukla2000 · Post by **dukla2000** » Mon Jun 16, 2003 5:51 am

Kostik wrote:1°) I can't find that "special lacquer", that's designed for coils. Is there something else I could use to prevent the coil from whining and that I could find easily ? Nail polish ? Glue ?

Well I read you could try wooden toothpicks between the windings - didn't work for me. Also I tried an epoxy glue 'coat' - also didn't work for me.

Kostik wrote:3°) I have a non-PFC PSU at home, and it doesn't have a coil, or at least, not such a big one. Could it be that this coil is related to PFC ? I'm just wondering.

I would stake a large sum of money it is a choke for the PFC circuit.
- My FSP 300-60BT has one of these (bolted and now grommeted to the lid of the psu case) - I never could silence it so retired the psu to one of my noisier systems.
- A Jou Jye psu I got had active PFC: instead of the large choke it had a daughter card with several components including a coil on a donut ferite core that buzzed. This is the one I tried to sort (without success) with toothpicks & epoxy. Fortunately the psu blew up and I threw it away.
- A Mercury (aka Deer) passive PFC I have also has the large choke mounted on the psu lid as per my FSP. I have also failed to silence this one.
- My current psu is a Powerup (aka Deer) with no PFC, and is silent.

In my experience PFC costs money as well as noise - I hope I have to eat my words at some stage in the future but (on the noise front) I am disillusioned with PFC! But hey, hopefully someone else here can enlighten us how to silence these damn things

Gekkani · Post by **Gekkani** » Mon Jun 16, 2003 6:00 am

In my experience PFC costs money as well as noise - I hope I have to eat my words at some stage in the future but (on the noise front) I am disillusioned with PFC! But hey, hopefully someone else here can enlighten us how to silence these damn things

What kind of noise do PFC ???

Post by **MikeC** » Mon Jun 16, 2003 9:31 am

On the other hand, it looks like the commonality among your PSUs is either lower quality brands or passive PFC, not just PFC. I have rarely experienced any buzz/whine problem with APFC units from Seasonic, and none so far with the Nexus, SilenX, or Fortron 400w APFC units. The Zalman 300W APFC sample is another story, it's a whiner, but this is already documented -- by jinu117(?), I believe -- as a flaw Zalman has owned up to.

dukla2000 · Post by **dukla2000** » Mon Jun 16, 2003 2:15 pm

MikeC wrote:... lower quality brands ...

- well certainly downright cheap

Previous to my FSP I doubt any of my psu's had any PFC: the only one that was quiet was a brilliant Seventeam 235W that is still running for a relative. I do hope it is just coincidental/personal to me: I remember (over 18 months ago) planning & researching for weeks with PFC as a number 1 'must have', and eventually finding my FSP for quite a premium ££. It really is a Jekyll & Hyde PC - built like a tank, reliable as the best, and performs like all the reviews say it should. But the noise has been a battle I lost: started with fans, put a Papst on grommets, still had noise, eventually ran it open 1 day without a fan and discovered what electronic noise was! It may well be a close cousin of the Zalman 300W?

And for me the perfect irony is that the absolute cheapest psu I have ever bought is electronically silent.

But OK, I hope I am the exception and one day will buy another 'quality' psu. Already I dread the process: what shop can you go into and ask to see the design inside the psu, and to listen to at "1am suburbia" levels of background noise! I guess thats what SPCR reviews are for

Also I am 'contrary' about the current trend for 350/400/450/500W psus - I only need 100-200W and want to be on the high end of the psu's AC/DC conversion efficiency curve, not in the pits! The fanless FSP 200-5P01 is tantalising - the bad news is that it has missed its Q1 launch by a long way

And the longer my current Deer runs stable & quiet the more contrary I will be! (Then again, 1 small fire will have me back on the straight and narrow!!)

Kostik · Post by **Kostik** » Tue Jun 17, 2003 5:00 am

Ok, thanks. Looks like there isn't much I can do.

I couldn't put up with the noise, so I put my 120mm fortron (PF) back in, and it's much better. With the cpu ducted and the thermistor a few millimeters away from the heatsink, it doesn't speed up too much. And at least it doesn't whine !

Another PSU-related question now, is it possible to trick the thermistor in the 120mm fortron into thinking the temperature is lower ? Assuming the fan controler is linear, but there is a minimum voltage that is fed to the fan when the temperature is below a certain value, then just tricking the thermistor into thinking that the temperature is 5°c or 10°c lower would turn the controler into some kind of "two stages" device : the fan would only speed up under high loads, and would stay slow in normal use.

Would soldering a resistor inline with the thermistor do that ?

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