please tell me my fan is faulty

[maphill]

Rather than disconnect, it would make a bunch more sense to put a wire adapter that lowers the voltage and reduces the RPM.

Anyway, I'm still working on a solution. More later, but my initial attempts to replace the fan did not improve the situation, though the rubber mounts did lessen the lower frequency portion of the noise. However, the rubber mounts won't work with the stock fan.

I have another idea that I'll be trying soon. I promise more detailed information and pictures soon.

Mark

[curvebender]

Rather than disconnect, it would make a bunch more sense to put a wire adapter that lowers the voltage and reduces the RPM.

As the fan revs up after boot, it implies that RPM can be controlled by software. Maybe this can be fixed in an update then?..

Anyway, I'm still working on a solution. More later, but my initial attempts to replace the fan did not improve the situation, though the rubber mounts did lessen the lower frequency portion of the noise. However, the rubber mounts won't work with the stock fan.

So you did replace the mounts? And the fan?..

I have another idea that I'll be trying soon. I promise more detailed information and pictures soon.

Can't wait to see (and hear!) what you come up with!!

[Davidb]

Rather than disconnect, it would make a bunch more sense to put a wire adapter that lowers the voltage and reduces the RPM.

As the fan revs up after boot, it implies that RPM can be controlled by software. Maybe this can be fixed in an update then?..

In fact, RPM *is being* controlled by software.

That´s the reason why it speeds up when you turn the keyboard on, and soon afterwards is slowed down once the OS stars running and handles the system.

The question rather might be if can it be slowed down more than it is now, which I doubt.

[aribo61]

So curvebender finally found me

I assume he was the guy who asked me to join the thread?

so here I am

My Kronos fan is still disconnected, since I wrote it in my blog, so it's working for twenty days now.

I currently have not much time to play, but when I play (may be every second day), it's for some hours.
The right button area is hand warm after may be 30 minutes or more and seems to stay at that level. As I wrote in the blog post, our room temperature is about 20°C now.

I think, the temperature is a little bit high (inside), and it will probably shorten the motherboards live time.
So I am thinking about installing a better fan which I would slow down, may be to 1500 RPM.

Before I removed the fan completely, I first tried several methods which I usually use to build quiet PCs, all with the original fan, but none of them was acceptable to me.
E.g. I used tie-wraps (word?) instead of the screws which i crossed between fan and metal sheet to decouple vibrations (which usually works well). I also tried some kinds of rubber for that.

I didn't try slowing down the fan, because at this time I felt the noise at boot time, when the fan suddenly slows down was still way too much (for me).

Btw: some guys in this thread told us, their fan would have max speed when switching the Kronos on, then slow down, and then go to max speed again and stay there, which is just the way my Kronos behaves.

But, some guys seem to tell us, their fan slows down and stays there? are you shure? This would probably mean, that we have different operating system versions. May be we should compare our OS versions?

Can we hope to get a solution (better software controlling the fan) with the big update coming next month?

[NavidSyed]

I personally do not think that KRONOS software controls the fan speed at all, because the actual dBA remains around the 39-40 after initial spike when you turn on the KRONOS, it might be a perception of fan being slowed?? I personally do not think that KRONOS software is controlling the fan speed at all, which is connected to the motherboard and is loud because it is a small fan, running at 3000 RPM at 12 v and is almost in direct contact with the metal body..has someone actually tested that fan speed actually varies during the operation of KRONOS?

[aribo61]

I'm currently not sure why the fan makes that noise...

First I thought "this fan is very silly mounted, there will be no problem to solve that".
As someone mentioned here, it's mounted against the side of the SSD with a metal sheet, and all is well connected to the big bottom metal cover.
So all the noise will be amplified by the cover.

But -- surprise! -- when I unmounted the fan, it was still very loud.
Yes, it wasn't as loud as before, but still way too much.
So I think the fan might be the real problem here, especially when rotating at full speed.

Then I am unsure about the real reason for that fan.
Currently I think it's indeed for just moving the warm air around, so it doesn't heat up in one corner of the case.

I'm a little nervous to open my Kronos (again).
When you open the bottom cover, the keyboard and the joystick unit are missing some support from it, so they start hanging around a little.
Also I want to develop an exact plan about what to do then, before I open it again. E.g. should I attach a monitor to the VGA port? should I attach the SSD to a computer and make a backup? etc.

[aribo61]

here the fan is rotating at the same speed all the time.

But it runs at lower speed for some seconds when it's in the first boot phase.
I assume the BIOS is controlling it for some time.
The motherboard docs should help out here.

Why should it slow down, if it would be a fixed speed fan connector?
I never saw a fan on a fixed speed connector slow down for some while after first running at full speed.

From what I remember, three pins (GND, 12V, speed-detector) can mean voltage controlled or fixed voltage (=fixed speed). Four pins should be PWM controlled.

[maphill]

I too tried a rubber mount and even a different fan (that was rated as quieter, similar amps and similar airflow). The rubber mounts with the new fan had reduced low frequency noise, but still a hum.

My latest guesstimate is that the SSD being directly in front of the fan is causing minor cavitation and that the hum is the frequency of the blades passing the SSD. I'm going to try using a 10mm spacer for the fan so that the blades do not pass right by the edge of the SSD. As soon as I get the parts I'll try it and report back here.

Mark

P.S. The SSD mounting bracket clearly has mounting points for a 2nd drive.

[maphill]

Additional information:

The best solution for quiet fans is larger fans, but unfortunately I measured and I don't think there is room for an 80mm fan. There is a room for a 70mm fan, but they are uncommon and often not quieter.

It is also possible that serially mounting 2 fans can make them quiet. I'll probably tinker till I find a solution.

Mark

[panrixx]

From what I remember, three pins (GND, 12V, speed-detector) can mean voltage controlled or fixed voltage (=fixed speed). Four pins should be PWM controlled.

There were a set of photos of the inside of a Kronos and scanning throught them it seems there are three cables (Red, Black and Yellow). The photos were not totally clear on these but it looks like just the three.

[maphill]

Yes, standard 3-pin control.

By the way, my guess on the fan speed: The power cycles from high, low, then medium are part of the startup procedure, maybe even controlled by the bios. Then once the OS takes over, I bet they set the fan to medium by default, and maybe raise it to high if things get extra hot.

But I bet they thought that medium was necessary for sufficient heat distribution considering typical safety tolerances.

One other theory: If enough heat sinks were mounted on the inside of the metal casing, the heat exchange would be sufficient to negate the need for a fan. But that would have been expensive and more difficult to manufacture.

Mark

[aribo61]

The photos were not totally clear on these but it looks like just the three.

I have some photos on my blog, too, please look at
http://korg-kronos-inside.blogspot.com
and yes it's a three pin connector.
Indeed, this was the reason I said "From what I remember, three pins (GND, 12V, speed-detector) can mean voltage controlled or fixed voltage".

[aribo61]

@maphill:

Then once the OS takes over, I bet they set the fan to medium by default, and maybe raise it to high if things get extra hot

my K doesn't seem to switch to medium speed after boot phase, I think it's full speed all the time just like after powering on.

I also never couldn't see a difference in fan speed between heavy use and no use at all.

I also think, that passive cooling by heat sinks could be enough.
I personally think, that the motherboard's and the chip's specs would allow very hot operation (I think about 90°C). But this may cause malfunction of e.g. the display and may be other components placed at the top of the case.
The hot air should gather at the top, so may be it could harm somewhere.
Perhaps the fan is placed in the center to prevent hot air from gathering there?

But -- with a disconnected fan I only notice heat at the right side, where the motherboard lives. However, this is from a raw outside perspective, I don't know how the temperature is distributed inside. But at least it looks like the display doesn't get hot without fan.

[NavidSyed]

KRONOS uses Intel Atom processor which do not require any cooling in general and are very popularly used in home theater PC's due to small size and less power requirement, the position of the fan right next to power supply makes sense to disperse the heat away from the CPU as power supply can get hotter, not the LCD, not the CPU not the motherboard, heat generated by power supply can accumulate and cause hiccups in performance of the CPU..

[dfahrner]

I don't have my Kronos 61 yet, but I may have to deal with this issue when I get it, so...has anyone just bought a quieter 60mm 12V 3-wire fan and replaced the one in the Kronos? There are a lot of them available online, with around 12 cubic feet/minute air flow and noise of 15 dba or less, and they don't cost very much...???

df