Amiga 3000D PSU Noise Reduction project

[StompinSteve]

Hello fellow A3000D fans

Are you like me, looking up into the sky to find that Airbus 380 flying by but it turns out to be the original fan in your power-supply?
Then look no further. Here is a solution

The challenge is to find a fan that fits perfectly, has roughly the same airflow properties but is as silent as can be.
I'm a huge fan of Noctua case-fans. They are silent, have liquid bearings, last forever and are vibration-free by design. They can be made even quieter with their "Low Noise Adapters" that they ship with many of their products.

I have been experimenting with several fans of several vendors and ended up with the Noctua "NF-A8 FLX" 80x80x25mm Case-Fan.
It is the same exact size as the original, minus the Airbus like noise-level.
It comes with rubber mounting thingies that replace metal screws. They isolate the PSU housing from the fan-housing, so that any vibrations from the fan do not resonate which adds loudness.

Some quick specs:
12V 3-pin (we don't use the 3rd wire which is for the tacho-signal)
Base RPM = 2000 RPM
Airflow and sound-level without a Low Noise Adapter = 50.4 m3/h @ 2000RPM - 16.1 dB(A)
Airflow and sound-level with Low Noise Adapter (NLA) = 41.4 m3/h @ 1650RPM - 13.0 dB(A)
Airflow and sound-level with Ultra Low Noise Adapter (UNLA) = 28.9 m3/h @ 1200 RPM - 7.9 dB(A)

The fan ships with two Low Noise Adapters:
NA-RC10 = Low Noise Adapter (UNLA) = 50 ohm
NA-RC12 = Ultra Low Noise Adapter (UNLA) = 140 ohm

As attractive as it may sound (pun intended), do not use the Ultra Low Noise Adapter NA-RC12. Yes it makes the fan inaudible but the airflow is not sufficient with the case closed and the A3000 under prolonged load.
The airflow is enough to keep the PSU itself cool, but it creates almost no suction through the front and top vent-holes in the PSU to evacuate enough air from the rest of the case.

The PSU fan does not have to do all the work though. I use a Noctua 40x40x10mm 12V fan between the left-front of the case (between the Daughter-board and the square hole in the case through which the wires to the Power- and HDD-LED board are routed). This fan is inaudible but blows enough air over the Chips at RP102 and U174, U256, C202 and Fat Agnus. I put little pure copper heatsinks on the hot chips in that area so heat-build up there is not a concern anymore, all the while being totally quiet.
This little fan sits on the lower Zorro-card rails (by lack of a better term) so that it can pull air from behind. This way, it is not necessary to drill a hole in the front of the case and have a fan suck air through the hole. It would be a mistake to remove the plastic Zorro card-rails so that the fan sits flush on the metal of the case. There will be no airflow as there is no open space behind the fan.
A side effect of this approach is that the lower two Zorro slots can no longer hold full length cards like a Fastlane Z3 for example. But a RAM board like the GottaGoFaZt3r 128/256MB will fit there just fine (and be cooled by the fan).

Use the Low Noise Adapter NA-RC10. The fan pumps enough air through with 41.4 m3/h @ 1650 RPM and with 13.0 dB(A), it is really quiet. The orginal PSU fan does 43 m3/h if my research is correct.

If you have an A3000D chuck-full with Harddisks and Zorro Cards al over the place, you might want to consider not using a Low Noise Adapter at all. The fan will run at 16.1 dB(A) @ 2000 RPM which moves a lot of air while still being massively more quiet that the stock fan. I like it more quiet so I run with the NLA but that is personal preference. Again don't use the UNLA because the lady will overheat in the summer.

So how to proceed? Simple. Remove the 100000000 screws that hold the two halves of the PSU together and unscrew the fan. Unclip the clip of the wire and out she goes. Cut off the little white plug from the fan and bury the fan 2 meters deep, never to be seen or heard from again. Good riddance.

In 3 of the 4 holes, through which the old fan was held in, insert the rubber mounting-thingies (2cm long brown rubber "pegs"). Use some lube as the pegs are a pain to pull all the way through when they are bone-dry.
The way it works is that you shove the holes in the fan over those pegs and then use pliers to pull the pegs through until it snaps into place. The peg in the corner is impossible to pull through with pliers once the fan is in place. If you manage to do it, tell me and I will worship you until the end of time
This is the reason why you will see 3 brown pegs in the first photo and not 4. But 3 hold the fan solidly in place so don't worry about not having 4 of them.

Snip off the 3rd yellow wire which is for the tacho-signal. We only need red and black.
Then, get a 50 ohm resistor ready or, if you don't have one like me, take the NA-RC10 Low Noise Adapter out of the box and butcher it until you have the resistor, still in its little heat-shrink condom, left over like in the second photo. I kept a few cm of red wire on both sides attached so my simple brain could do "duhhh black wire onto the black wire and the red wire onto the other red wire with the little resistor thingy in it". Solder them together and connect the white plug to the other white plug which still attached to the PSU's guts. Power on and test.

Wrap it up with a good dose of electrical tape and route the cable such that it does not touch hot things (3rd picture). Test, then put the PSU back together and into the A3000 and you are done. Get beer, you deserve it.

[KONEY]

Cool! In both senses ;D

[Gorf]

Thank you!
I will have a look - I will probably miss the familiar noise of my A3000 *g*

[Mathesar]

I replaced my A3000D fan as well some while ago.
See here: http://eab.abime.net/showpost.php?p=...1&postcount=17.
I used a NF-A8-PWM though. The PWM version produces slightly more airflow and also more pressure. My thinking was that the pressure might be more important than the maximum airflow as the A3000D is quite crowded inside.
I did a test using a trashbag and found that the nf-A8-PWM in full speed moves about the same amount of air as the old panaflow.
With the low noise adapter it moved considerably less air than the orginal panaflow fan. I think it is down to the generated pressure and would thus recommend to not use any low noise adapter.

[StompinSteve]

Update: to address the heat concerns in the "Zorro area", I devised a solution for that side of the 3000's chassis as well.

My A3000D is perfectly cooled all around from now on. All the "hot" chips in there have little Heatsinks and the Zorro cards stay nice and cool.
Two of these beige "Zorro card holders", the middle ones, are removed so that the fan can breathe freely (also prevents turbulence and thus extra noise).
The top "Zorro card holder" holds the fan. The fan is stuck on with very strong industrial tape (double-sided but the yellow band I left on because there is nothing to be glued on there). That fan sticks like a Paris Hilton to a rich guy and is not going anywhere.

I used a Pabst industrial case fan, a 70x70x15mm model with a standard 3-pin fan-header. This fan is too loud for my taste but thanks to a Noctua NA-RC11 98? low-noise adapter (3-pin) it is now quiet but still moves enough air. Together with my Noctua Power-Supply Fan-Mod, the 3000 is nice and silent ? (you can hardly hear it).

At the rear, two of the standard closed Zorro-slot covers (the ones at the very top and very bottom) where replaced with "grated variants" from a server. The bottom one is just painted black, so that's not a hole/slit. It's just hard to see on the bottom picture.
Thanks to the two grated covers, the warm air can be evacuated even better there.

[patrik]

LOL @ the Airbus 380 comparison! Funny because it is true, the A3000 has an obnoxiously loud stock fan.

I think a big reason it sounds so much is that it is running waaay to fast for how much air is possible to move through the holes in the PSU and case, causing it to constantly work very hard against that limit, causing that troubled loud sound when forcefully trying do its work.

Also replaced my fan with a Noctua fan. I think it’s the PWM variant, it is grey. If I remember correctly, I used no low noise adapter. It is not whisper silent, but a dream compared to the original and cools really well.

[seb132]

Originally Posted by patrik

LOL @ the Airbus 380 comparison! Funny because it is true, the A3000 has an obnoxiously loud stock fan.

Not even close to a good joke. I trust none of you have traveled in an A380 before: it is the NOCTUA of all planes! Dead silent!

Anyway, great job StompinSteve, your post is a "sticky" for me, now...