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 Post subject: MikeC on empty space in the Fortron Aurora
PostPosted: Fri Apr 02, 2004 11:36 pm 
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Well folks, I think I've figured out the answer to these comments by MikeC in his review of the Fortron Aurora: "The unpopulated portion of the printed circuit board by the capacitors is unusual, compared to the many other already seen that were OEM'ed by Fortron-Source. On most of those, there is no bare space on the board at all. Whether this lower PCB parts density means anything is not a question easily answered."

MikeC, I think there IS a simple answer, and I don't think it is unusual... I think it is a "feature" if you will of mass production. Basically, Fortron left that unpopulated space there because you reviewed a model that had NO PFC. Models that have passive PFC have a large choke coil in that empty space. A good example of a model with passive PFC and that choke coil is the Nexus NX-3500, which is clearly just a rebadged Fortron Aurora with that special Yate Loon fan.

Look carefully at these pics of the Fortron and the Nexus NX-3500 side-by-side (try to visualize the Nexus image flipped around), and you'll see what I mean. Notice that the layout of the heatsinks and circuitry is IDENTICAL apart from that PFC choke.

Image
Image

In fact, for fun, I even compared the results of Mike's testing on the two, and if you look at the charts, you'll notice that practically every single one of the figures is close to, if not dead-on identical! :lol:

Even the power factor measurements were similar: 0.62 - 0.71 for the Aurora, compared to 0.64 to 0.72 for the NX-3500. With these two units being almost identical, apart from one having PFC and the other having none, I'd say this is a PERFECT case study in PFC circuits. The verdict is clear: passive PFC clearly makes virtually no difference whatsoever. I'd say for all of you considering PFC in your choice of PSU: Go for active, or none at all. Passive PFC clearly doesn't make much difference (if any) and the choke coil is simply another HUGE potential source of coil noise. :twisted:


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 Post subject: Re: MikeC on empty space in the Fortron Aurora
PostPosted: Sat Apr 03, 2004 1:24 am 
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zuperdee wrote:
I'd say for all of you considering PFC in your choice of PSU: Go for active, or none at all.
Couldn't agree more.
zuperdee wrote:
Passive PFC clearly doesn't make much difference (if any) and the choke coil is simply another HUGE potential source of coil noise.
ALL my passive-PFC chokes have vibrated on the psu case causing noise I could not cure. Avoid passive-PFC unless you are a masochist. :twisted:

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 Post subject:
PostPosted: Sat Apr 03, 2004 1:02 pm 
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Yeah--I must say, I used to think either were better than none, but after seeing how little difference it actually makes between these two nearly identical units, I've now officially changed my mind. Active PFC is also clearly less prone to vibration and noise, offers full-range input, better power factors, and is generally much more robust than Passive PFC. (It is less susceptible to brown-outs, drop-outs, and simplifies overvoltage protection.)

I found an interesting article at Reed Electronics that gives more detail on the regulatory background, and the technologies involved. It also explains why it isn't more prevalent in the United States--apparently, the U.S. opted to make the supply more "robust" instead (whatever that means).

Here's the article:
http://www.reed-electronics.com/ednmag/ ... 2F6%2F2000

I guess this is in part why my next PSU is going to be a Fortron FSP400-60PFN. (What the Zalman ZM400A/B, the Silenx, and the Nexus NX-4000 are based on.)


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 Post subject:
PostPosted: Sat Apr 10, 2004 11:58 pm 
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All I know is I want a vendor for Yate Loon 120mm fans. These kick butt. I took one out of fortron and it competes w/ both my pabst 4412 and NMB b 20's at low volts. I bet it's cheap too.


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 Post subject: Here's hopin'
PostPosted: Sun Apr 11, 2004 4:26 am 
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Hello:

Beerhunter wrote:
All I know is I want a vendor for Yate Loon 120mm fans. These kick butt. I took one out of fortron and it competes w/ both my pabst 4412 and NMB b 20's at low volts. I bet it's cheap too.


Yes, they do! I'm not sure why some folks have tried replacing them in the Fortrons -- they move a lot of air, and run at very low speeds *smoothly* and quietly -- no clicking, and virtually no bearing noise... 8)

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