Installing extra fan on simucube

I’m in the process of assembling a Ioni pro hc/simucube build with an sdr 480. It’s going to be driving an AKM54K and I’d like to install a secondary fan to cool the regen resistor and ioni board.
I’m already using the fan control from the simucube to power a case fan which cooks the ps and board all up - what is the best way to wire in a second fan for cooling the pro hc and regen? Any recommendations on placement/further advice?

I believe if I remember correctly there are two 5v outputs on the Green bus where the SimuCUBE fan is installed you can use the second 5v on that to power a second fan… There is also some tie downs to allow you to strap a small fan right next to the Regen Resistor.

To tell you the truth though you probably don’t really need to do this as unless something is messed up in your configuration the Braking resistor won’t really ever get hot enough to kill itself, especially if you have a newer (2nd gen) board with the dual stacked resistors.

Thanks for the reply, that makes sense, can I share the PWM enabled ground of the first fan to speed control if I chose to do this?

I’m thinking this is a good idea out of an abundance of caution, if nothing else - I will be driving a AKM54K which pulls a lot of current from the IONI, I’m intending on running it hard so there’s going to be a lot of me fighting the wheel and pumping voltage back up the line to the regen resistors.

What Simucube fan?
My IONI Pro HC Simucube from SimRacingBay (in the Cooler Master ATX case) has no fans operating. The case has a fan but it’s not wired up and I was told this is normal.

Should I have a fan going?
I have the 720W peak PSU


The Large Mige actually pulls more than the 54K and there are several running without a fan at 25AMMC, but it is precautionary…

The only concern with running the grounds the same would be if there are any current limits on those points of connection.

@GlobeSpy - I had an 80mm fan (single) for my SimuCUBE when running in a REALLY tight small case with a SDR PSU and Large Mige. I now have my Simucube in with my Computer so it all uses the same case fans.

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I think we will have to wait for @Esa to comment on whether the 5V regulator can drive 2 regular fans. However, with the latest firmware patches on IONI side, there should be no need to install a separate fan for IONI.

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I have done lots of testing around this and would not recommend driving a 2nd fan, as it will indeed borderline the current available from the 5V reg with unintended consequences.

A single small fan is enough, my setup has never been below full 25A MMC setting, and I only use a small 70mm fan affixed directly to the holes on the SimuCUBE to ventilate the PSU and IONI. I have also never lost a single IONI or SimuCUBE due to overheating issues.

And yes, I have have done pretty funny things over last few years to my hardware. So a single fan ventilating your case is good enough, all you need/want is to remove stale air, nothing drastic needed.


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That settles it. Not necessary, potential issues due to over-drawing on the 5v line. I won’t be pursuing this. Cheers all.

Cheers bud, wise decision.

I still don’t know how to get just one fan working!!
The case that my build came in from SimRacingBay has a fan (CM110 case (dustproof, silent 12cm fan inside )) but was not hooked up and sounds like I likely don’t want to hook it up internally?

Now I’m worried about overheating and have no idea how to get a fan working.

The fan is working - it’s just super silent! (my bad)

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Anyway, herewith 2 pics to show how I did mine, using the original fan-mount location on the Simucube board. Easy, simple, elegant.

@Globespy: You can see where the fan connects to the green header on the Simucube, the first 2 points on the block. Make sure you get polarity correct, and it is the furthest 2 points away from the edge of the board. See first picture below.

And it works very well :wink:

I see you had an sdr-480-48p, but went with a larger one. Why? Was the 48p not strong enough?

I don’t really want to bump or take over the topic, but I saw by incidence when I was just scrolling around.
I’m about to buy an sdr-480-48p so therefore the concern


Phillip runs some very, very large Kollmorgen motors, which require such high power PSU.

Hi Mate,
As per Mika’s answer. On top of the large AKM servos I run nowadays, I also have a pretty power-hungry Lenze servo I play around with that actually uses the most power of all servos in my possession.

My test AKM65L (640W) and Lenze MCS 12H15L (711W) will constantly drive the SDR-480 to exceed nominal power capability, which is not a good thing from a longevity and reliability POV.

Hence the SDR-960 workhorse, which is a great PSU, provided you have a 220-240VAC inout source - it is not suited to 110-120 VAC inputs, if you want high power output, that is.

Hope it makes sense.

I have anyway posted a spreadsheet earlier that highlights PSU wattage requirements for most commonly used servos when combined with the SimuCube.