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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: First Ninja on October 28, 2018, 03:35:25 PM

Title: Replacing a noisy A3000 PSU fan - the elegant solution?
Post by: First Ninja on October 28, 2018, 03:35:25 PM

Hi everyone.

As any owner of the Amiga 3000 probably can vouch for, one of the machine's shortcomings is its loud PSU fan. Compared to just about anything available on the market today, the original A3000 fan is anything but quiet.

Since my A3000 is in need for some minor maintenance, I'm willing to part from my original PSU fan - and here's where some help might come in handy. Browsing through some old threads here on Amiga.org and other forums, I've realized that...

... the A3000 uses a standard 80 mm fan.
... replacing it is a matter of cutting the original power wires, and (somehow) latching the wires from the new fan onto the original wires from the A3000 PSU.

Here's a couple of photos showing what the process might look like:

(https://i.imgur.com/KJlaCbu.jpg)

Although I'm sure that the process shown on the photos makes for a solid replacement, it all seems a bit too "hacky" to me. I'd much rather go for a a more elegant solution that uses a proper set of suitable male/female connectors on each end of the two wires (so you'd be able to disconnect the fan from the CPU, in case you'd ever want to replace the fan at some other point in the future).

All of this being said, here are my questions:

What sorts of connectors would be best suited for this project? (product links/example photos are appreciated!)
Am I right assuming that the polarity of the Amiga 3000 wires determines whether or not the fan will blow air outside of the A3000 PSU or suck air inside it?
Seeing that both solutions (https://pressf1.pcworld.co.nz/showthread.php?47317-Power-Supply-Poll-Do-your-fans-suck-or-blow) are in fact a thing, does the A3000 PSU fan blow hot air out of its casing, or suck cool air into it?

Any help is much welcome - thank you in advance!

Title: Re: Replacing a noisy A3000 PSU fan - the elegant solution?
Post by: kirk_m on October 29, 2018, 08:13:20 PM

I am pretty sure you can just unplug the old fan from the PCB on of the power supply. I am sure that's how I did mine. But, since you cut yours already, just spread the wires out on both halves ( like a fan) then, twist both ends together, end to end, and apply solder. Heatshrink tubing afterwards.

Like this:

https://www.instructables.com/id/Soldering-Tutorial-Inline-Splicing/

No, the polarity of the wires has to be matched red to red, black to black. The yellow wire is for speed control, but, that PSU isn't capable of controlling speed, it's all or none. That's not what determines what way the fan operates. The way you place it back into the case is how it directs flow. My A3000 blows air OUT. It sucks cool air in from the grates on the front/underside of the faceplate of the case, and, from the perforations in the backplate on the side of the daughterboard where expansion cards are plugged.

Title: Re: Replacing a noisy A3000 PSU fan - the elegant solution?
Post by: NorthWay on October 30, 2018, 08:21:12 AM

I ripped the old fan out of my A4000D and put in a new low-noise one - I just routed the 4-pin Molex(?) power connector back into the cabinet and connected it to one of the internal power plugs.
Might be an easy option in an A3000 too.

Title: Re: Replacing a noisy A3000 PSU fan - the elegant solution?
Post by: Oldsmobile_Mike on October 30, 2018, 11:25:22 PM

I remember when I replaced the fan on my A2000 I thought I was being "smart" and got one of the ones with the variable switch to adjust the speed. But then I needed to drill a hole through the back of the power supply to run it, and another hole through the back of the A2000 case for it. Not so smart! ;D

Title: Re: Replacing a noisy A3000 PSU fan - the elegant solution?
Post by: First Ninja on January 03, 2019, 09:20:16 PM

kirk_m, NorthWay and Oldsmobile_Mike - thank you for all of your inputs and for sharing your own experiences. kirk_m - I think you misinterpreted my original post. Those photos I posted aren't mine, and fortunately not I can't take credit work the modification that has been made to that PSU. Like I said, I found that particular solution way too "hacky" for my personal taste. Since I was looking for a more elegant solution, I reached out here for some ideas.

NorthWay - I sort of went down the same route you've taken. Instead of opting for a 4 pin Molex, I chose the 2 pin variant (also known as "Tamiya plugs" - a matching pair was around €2.53 at an R/C hobby shop). The replacement fan in question is the PureWings 2 (https://www.bequiet.com/en/casefans/506) by Be Quiet! (https://www.bequiet.com/) (around €9.65). Just like the A3000's stock fan, it's a 12V 80 mm fan. After a bit of tinkering, cleaning my dust-ridden PSU and installing Kickstart 3.1.4 in the process, I managed to get everything back together in working order. I can't stress the difference enough - with Commodore's old fan out of the way, the most noisy component of my A3000 is now the SCSI disk by far.

For anyone interested in seeing parts of the process, here are a few photos I took of said surgery!

(https://i.imgur.com/lUFIgaq.jpg)

Oh, and to anyone who comes across this post looking for the same solution I did - just like others have already mentioned in this thread, the Amiga 3000's original fan does suck air out of the case (and not the other way around). Closer inspection of the fan Commodore chose reveals that the direction of the air flow is shown on the fan by a tiny arrow. To make sure that the replacement fan spins in the same direction, be careful to:

Hook up the new fan to the right wires (i.e. red wire from the A3000 PSU to the wire that connects to pin 1 on your new fan, and blue wire from the A3000 PSU to the ground wire from the new fan).
Mount the new fan in the right direction - again, the air flow arrow should be pointed outwards.

Title: Re: Replacing a noisy A3000 PSU fan - the elegant solution?
Post by: QuikSanz on January 05, 2019, 03:56:20 AM

Blue is European standard for ground or " - minus ". Any PSU fans originally blowing in were probably before they knew better and they all have arrows.

Title: Re: Replacing a noisy A3000 PSU fan - the elegant solution?
Post by: dschallock on January 05, 2019, 08:21:13 AM

I would only caution (from experience) that the psu fan on the 3000 is the sole source of cooling. If the new fan is not pulling as much air as the old one did you could get heat related issues on an already tight case configuration.