Retro-fit fix for FS-4 noisy fan questions

[Daniel Kohl]

I am contemplating ways to correct the noisy fan problem on my FS-4.

Before I start sawing my FS-4 apart, there are a few things I would like to have some input about.

Can anyone explain to me why some HDD devices need, or have fans, and others don't.

I have the feeling that the FS-4's cooling system is one of the reasons that it works reliably, but I don't understand why some devices can get alone with more heat and some less. There are some professional cameras that get very hot and they don't use any audible fans.

I realize that the FS-3 and FS-4 are in effect specialized computers, so I can understand why they would need a fan, like a laptop does, to cool the heat produced by the CPU. I haven't used the FS-3 for a long time now, but I don't remember there being an issue with it making fan noise. This is probably due to its metal chassis, which looks like it was designed with cooling fins in mind.

One of my ideas is to add Aluminum elements to the FS-4 with heat pasted connections to the units CPU. I would also think about repositioning the fan so that it is blowing more directly onto the units IC boards and/or these aluminum elements. Even if this would mean adding a bulge to the side of the FS-4, I think that it would be worth it. The unit it quite enough in quite mode, it's just too loud when it goes into medium and high fan speed.

I have also noticed that the placement of the fan on the back of the unit is somewhat impractical. One of the reasons due to the fact that the unit is usually placed on its back when put down on a tabletop (covering the fan in-take for the most part) for connecting to a computer. The accessory stud prevents the unit from lying entirely flat, but I wonder if the unit is making optimal use of the fan in this position.


Thanks for any ideas

[David Suthers]

Daniel,

While I'm not familiar with the FS-4, I have followed the noisy fan complaints pretty closely, so maybe I can help. The first thing I would do is get the specifications from the fan and see if there are any quieter fans available with the same or better specs. Look at home theater PC websites for listings of quiet fan manufacturers.

A thought I had is to check to see if the "high speed" mode of the fan is excessive for the cooling needs. What I mean by this is that after a certain point, blowing the fan faster doesn't cool any better. If the FS-4 is over-designed this way, then it is possible to put a potentiometer in series with the fan power and you can manually adjust the fan speed for optimal cooling (and noise reduction).

An old computer "modder" trick is to lap any heat sinks. The flatter, shinier, lapped heat sink will carry away more heat than a plain cast one. If any heat sinks are attached with mechanical clips (versus being glued on), you can also replace the heat sink compound. Artic Silver here in the states is very popular and also very good. These steps won't make a large difference, just a few degrees C, but every little bit helps.

Another source of noise could be turbulence caused by restrictions in the air inlet/exhaust. You can tell this pretty easily by opening the case and listening to the difference in fan noise. A little case trimming here could pay off big, but be careful. Indiscriminately trimming material could disrupt the airflow design of the case.

If none of these work, I'd look at going with a larger fan that turns slower. This may require extensive modification to the FS-4 case, but from your "Frankenstein meets XL1" web page, I'm sure this doesn't scare you.

[Daniel Kohl]

Hi David,

Thanks for you quick response.

I am indeed not afraid of modifying the FS-4's case. I'm even looking forward to it.

I have also looked into quieter fans. But they are pretty damn expensive, especially since I don't know if it will be significantly quieter.

I like your second suggestion. But how can I check if the unit is blowing excessively without letting it overheat. And although no one can answer this, I am wondering why the engineers at Focus would choose to over design it in this way. I do have the feeling that the unit is not cooling effectively. I was actually thinking about putting an on/off switch on the fan for when I'm shooting in quieter situations. Your potti suggestion is good.

I couldn't find any heat sinks in the unit, and I am assuming that the CPU is the biggest IC and the only one that is removable in there. But I am a retrofitter and not a computer "modder" (maybe I will become one some day). I'll be looking into heat sinking. I've noticed that there are some web site out there that are very helpful in this area. Thanks for the tip about Arctic Silver, I'm sure that I can get it here as well.

The FS-4's fan is 50% blocked by the 2.5" HDD housed in the unit. I don't know if this is causing noisy turbulence, but I can't imagine that having half of the fan blocked, is making optimal use of its sucking power. That is another reason why I am thinking about mounting the fan on the side of the unit. I bet if it is in a better location it won't have to be bigger.

Thanks a lot for you input.

[Dan Diaconu]

Daniel,
Although my post is not of not imediate help, you could check:
http://overclockers.com/
I used to read preety much all written about cooling (water and mini compressors) till mid of 2003. You could find usefull ideas and tips. If you need specific help (I did a complete water cooling on a PC) I could give you a hand if you need something machined or so... Good luck.

[David Suthers]

If the fan is 50% blocked by the hard drive then I'd start there. Measure the thickness of the fan an see if it would be possible to install a thinner unit. Use some small washers under the bolts to gain some clearance around the fan. The larger gaps should get you better airflow and less noise from turbulence.

On my suggestion that the fan is blowing exccessively... you can check this by feeling the fan exhaust after the unit is fully warmed up. Maybe after an hour of recording, or when the fan kicks up to high speed. If the exhaust is cool, or doesn't change temps significantly, then I'd say they're running the fan unnecessarily.

When most electronics are designed, there is an minimum & maximum ambient temperature specification. Focus may have designed the unit to be used in 40C temps and that's the reason for the high speed fan in the first place. If you never operat the unit in temps higher than 25C then the fan may never need anything more than slow speed. It would be interesting to know if the fan change speed is on a timer, or a temperature probe.

Good luck.

[Daniel Kohl]

I made a few interesting discoveries last night.

The FS-4 has a utility section which displays a temperature. I don't know exactly where the thermostatic probe is located, which delivers this value but I'm assuming that it's measuring the air temp in the unit.

I also discovered that the acceptable sound that the unit makes when it is first turned on, is the sound coming from the unit's HDD. There is no "low" fan mode. The fan is off until it kicks in when the temperature reaches around 41 deg. C, based on the FS-4's own status readout. Also when the fan goes on, it stays on. The loud fan doesn't manage to cool the unit down enough to turn itself off. The air coming out of the exhaust vent feels cool to my lips, but the temp readout only fluctuates between 40 and 39 deg C. The fan is audibly louder at 40 deg. C than at 39. That means that there are two speeds (loud, and louder).

This also means that it might be an option to install a slow moving (quite) fan that prevents the unit from reaching 40 deg C in the first place. The only down side to this would be energy drain, but that would be definitely worth the silence.

Thanks guys for your suggestions. The over-lock site is damn cool (no pun intended).

[Daniel Kohl]

Ok, I removed the fan from the FS-4. And discovered that it is not loud at all. The fan itself is practically inaudible when it is running. It is, at least, as loud or quieter than the HDD, in the unit.

The main reason for the fan's noise is most likely that it is mounted directly to the unit's case with three screws and no vibration isolation. I think that the units case is acting like a resonance body and this is amplifying the mechanical sound of the fan. When I hold the running fan in my hand, I can feel it but, I can't hear it, unless I hold it right next to my ear.

So one quick fix may be to install rubber washers or something to isolate the screws from the case.

I also noticed that the fan is blowing fresh air into the unit (or more accurately at the back of the HDD). That's probably the reason I couldn't feel a temperature change of the air coming out of the inlet. I'm wondering what the advantages and disadvantages of drawing the warm air out of the unit are, as opposed to blowing fresh air into the unit.

The FS-4 is very well vented, it seems to me that if the fan were drawing the air out, instead of blowing it in, fresh air would enter the unit from all sides and that this would cool the unit more effectively. Is this possible?

[Dan Diaconu]

Originally Posted by Daniel Kohl

The FS-4 is very well vented, it seems to me that if the fan were drawing the air out, instead of blowing it in, fresh air would enter the unit from all sides and that this would cool the unit more effectively. Is this possible?

Always possible. Try it. Rubber will do fine (double sided tape even better)

[Daniel Kohl]

Thanks Dan,

I just cut a window in the side of my FS-4 big enough to place the fan in, with a little room to spare on all sides. The window is on the lower right edge of the unit on the hight of the navigation keys (I think the CPU is around there). I used two spots of hot glue (to which I am very partial), but double sided tape would probably be much more vibration insulating. I turned the fan so that it is drawing the air out of the unit. I taped up the gaps around the fan and the vents adjacent to the fan, with scotch tape.

The unit is now acceptably quite for filming in normal interview situations. And the fan is now able to change the temperature in the unit enough to turn itself off. After it has gone on for the first time, the fan goes off after 30 sec. and then goes on again after 30 secs. and so on. I don't know if this is bad for the fan or not, but it shows that the fan is cooling more effectively.

Unfortunately this retrofit will immediately void all guarantees on the unit. At least we know that it is possible to quiet the FS-4. Maybe Focus would consider making a FS-4 Pro S, in the future.

[David Yuen]

Once the "patient" is all patched up, you'll be posting a picture?

[Frank Yap]

I don't think the fan is for the HDD (it should not), since it runs at 5400rpm. Faster HDD like 7200 and above requires fan, they generate lots of heat.

I've modified my FS-4 as well (not fan related) and also noted that the fan is half blocked by the HDD. And you're right, the unit has ventilation holes all over so sucking air out (like most computer chassis fan) is more efficient.

The part number of the fan is KD0502PEB2-8 which is a low noise fan.
There is however from same mfg a super low noise fan KD0502PEB3-8.

Fan info: 25mm, DC 5V, 0.6W

[Daniel Kohl]

The "patient" is patched up. I am planning to do some plastic surgery (literally), and grill work, so it won't be going out into the public like this.

http://www.marq5.de/Fan_Retrofit/index.htm

The fan would physically fit further into the unit's case, almost to the point that it would be flush with the case's original outside dimensions, but this increases the noise level considerably due to air turbulence. The white tape is covering the vents directly next to the fan, and I taped up the vents on the bottom right side below where the fan is as well. This causes the fan to draw (I hate the word suck) fresh air from the opposite side of the unit across the IC boards.

Getting a quieter fan might be a good idea, this fan, mounted like it is, seems to be just a little louder than the HDD. But the noise level is acceptable for the kind of work I do. I also like the fact that this retrofit makes use of the devices own parts.

The operation took about 15 minutes, (without plastic surgery) and other than the massive changes to the case, required no non-reversible modifications.

[Daniel Kohl]

I've added a few pictures to my retrofit documentation.

The fan is now held in place with rolled-up double sided tape strips. I also built up the case with some two component epoxy putty called "Turbo Kit" here in Germany. I don't really mind that it's green. I also cut the side of the FS-4 caddy so that the retrofitted FS-4 fits into it, which it does nicely.

I am planning to replace the double sided tape with black silicon, and I plan to fasten a protective screen to it one of these days. Although a screen doesn't really seem necessary.

I wanted to field test the unit the other day but I forgot the FW cable. Didn't matter because the client just wanted a tape. However, it goes to show, that the added paraphernalia can become a disadvantage in unexpected ways.

Another lame-brain warning, is that the FS-4 likes to have itself turned on by anything that may rub up against it. It's not what it sounds like.

What I am trying to get at is, that I would not suggest packing the FS-4 together with other gear that can move around. You may discover that the battery is dead because the unit was on during transport.

Cheers