Dreamcast Fan Replacement

The fan on my VA1 (late model, NMB plastic fan) had been making clicking noises and a high pitched whine so i was set on replacing it.
Some problems presented itself and the solution i ended up on didn't present itself by researching on the web.

Upon research these facts presented itself:
- Stock fan specs: 30x30x10mm, 5v, at 9000rpm (according to old datasheet)
- The Console won't run without a fan tachometer signal
- I could not find any 5v fans with the required tachometer signal (yellow wire)

I ended up taking the route of getting power directly from the PSU and only connecting the tachometer line to the fan connector.
The replacement i arrived at was a Sunon MC30101V2-G99 (30x30x10, 12v, tach line, 8000rpm).

The Problem: The console won't accept a standard PC fan tachometer signal
A VA1 Dreamcast will not run for more than a few seconds if it does not detect the fan spinning, this likely applies for VA2 units as well.
It does not matter if you use a 5v or 12v fan, this problem persists.
Research shows this Problem being fixed by using a 555 timer circuit that simulates a signal the console could handle, but in truth the solution seems to be much easier.

When trying to measure fan speeds using a microcontroller you usually have to connect a pull-up resistor between 5v and the fans tachometer line, in the Dreamcast this resistor looks to be built into the standard fan.
PC fans do not have the pull-up resistor built in.

The Solution: Adding a pull-up resistor between 5v and the tachometer line
By simply adding a 10k ohm resistor between the 5v and tachometer pins on the fan connector the console starts running without any issues as long as the fan is correctly wired up.


For a 12v fan keep the resistor between 5v and tach Only move the red wire to 12v on PSU

Be aware that i am by no means an expert in the field of electronics and that this information may not be entirely correct.

The Aftermath:
In the end replacing the fan got rid of the clicking bearing noise but once you close the top-case you still hear a high pitched noise.
My assumption is that the design of the case somehow allows high frequency vibration to resonate.

Running it at full speed this fan also moves significantly more air than the original and thus creates a lot of air flow related noise, once you reduce its speed the high frequency sounds become apparent.

I may add pictures to illustrate all of this better, please excuse the messy formatting of the post.
Any input on the matter is appreciated.

 

I looked into this a couple years ago. The problem is that all 30mm fans are inherently loud due to the size, the number of blades (more = quieter) and the limited RPM choices. When you move up to 40mm size there are more options. There is still air flow noise but the sound is more pleasing.

I tried to build a custom 40mm bracket/duct back then but somehow miscalculated the placement of the lid ejection mechanism (interference issue) and had to shelf the project.




Someday, I like to revisit this project again.

 

Damn I really need to invest in a 3d printer. You make some cool shit @BuffaloWing

 

I cut a hole in the case where the air slits used to be (better air througput), and installed a bigger fan on the outside instead. The console gets placated by a 555 timer, which allowed me to add a manual speed control to the fan (runs as slow as I want, even off). Won't win any beauty contests but gets the job done with a minimum of noise.

 

I'd buy that.

@OP, so you did not use a 555 timer, and got the fan rpm pretending like everything is fine anyways? That's great! Could you elaborate a bit on where the 10k Ω is connected? Between the fan (or any) 5v and the tachometer line?

 

I have added a picture illustrating how i connected things, this is assuming you use a 5v fan.
If you use a 12v fan simply connect the red wire to a 12v point on the PSU, in this case you still connect the resistor to the 5v pin on the fan connector.

Pull up resistors are common when connecting signals to microcontrollers, the original fan already had this built in which goes against the standard for computer fans.
This way the console can read the fan RPM just like it would with the stock fan.

Hopefully this clarifies things.

 

hi bro, its works then , how about noisy , it seems its an quite nice fan with magnetic levitation to reduce the noisy

the original dc fan be the panasonic model:
UDQFHAB05F
DC5V 0.08A
0301
here is the datasheet
http://media.digikey.com/pdf/Data Sheets/Panasonic Fans PDFs/fhb_ab01_hab05.pdf

i being watching this others models too of 5 volts but the rpm seems different. probably soon i buy one to see how it works. if reduce the noise hopefully.

Sunon 30mm X 10mm Maglev Fan 5v Dc 3 Pin Conector gm0503pfv2-8

http://datasheet.octopart.com/GM0503PFV2-8.GN-Sunon-Fans-datasheet-5401739.pdf

SUNON 5 V 0.9 W KD0503PEV1-8 3010 3 CM

http://images.100y.com.tw/pdf_file/16-SUNON-KD1204PFB2.MS.pdf

 

I've been asked by @PearlJammzz about this, so I thought I'll just post what I posted earlier here. If you have a 3D printer, here you go. It's not perfect as I stated below. I want to redo this again, but if you want to give it a try it's down below. This version will not work, but if you feel you could do something with it, please do.

" I've taken another look awhile back, but I decided to put it on hold for a number of reasons.

First, the 3-pin fan I was using wasn't interacting which Dreamcast's speed sensing circuitry anymore. Before I build the 3d model duct, I was able to run that fan without the system shutting down. But when I revisit the project last time, I wasn't able to use the fan without the system turning itself off. Wasn't sure if I was mistaken the first time or if I damaged the fan's 3rd pin/circuit somehow. I never got around to get another fan to rule this out.

Second, I've come to conclusion that in order to use a square 40mm fan, at least one corner (or maybe two) of the fan's plastic frame need to be cut/trimmed to clear Dreamcast's lid ejection mechanism. There is just not enough space in there to cram the entire fan in tact. While cutting is not entirely a deal breaker, I just prefer not having to. I've noticed some fan cut more cleanly than other. Depending on the manufacturer, some frame will shatter when cut with flush wire cutter while some will just snip off cleanly. Ideally a fan with round frame/housing will be great for this application, but I'm having a hard time sourcing a round 40mm fan, let alone one with 3-pin with speedometer.

Third, I want to totally redesign the duct because the prototype I made has the duct opening sitting lower (about 5mm) than it should be. I'd like to revisit this again, but I really need to resolve the first two issues stated above first."

 

How about Noctua NF-A4x10 5V? It has a tachometer signal. It is advertised as near-silent (<18db) at 4500RPM. It does not have a round shroud, unfortunately. I estimate the original fan to have an airflow of between 3.5cfm and 6.5cfm from datasheets of other similar fans, and Noctua claims about 5cfm but according to independent measurements comes out closer to 3.5cfm. I guess this simply needs to be measured in real use.

I'm not sure whether there's injected noise current issues from fan tacho circuit and whether one shouldn't install also current limiting of maybe 1kOhm between the pullup and the logic board tacho input to avoid damage to the console logic.

 

PearlJammzz says he is getting a Noctua, so he'll probably chime in on this. As for the pullup resistor, I'd like to know also, since I couldn't find anything on the spec sheets that I was able to find.

 

I picked up the Noctua fan and tried it on one of my spare DC, I also printed BuffaloWing's fan adapter and to make it all fit I 3d printed a custom eject latch that would allow it all to fit in. The Noctua Fan did require the pull-up resistor in order for the Dreamcast to stay on.

 

So how does the Noctua Fan sound like? Significantly better?

 

There is still some sound but it is significantly better. I plan on doing a side by side video will swap it into my USBGDRom unit. I will upload the new latch for anyone who is interested in it, but that will have to wait until I make it home tomorrow.

 

Sorry for the late reply, I have been out of town.

That said, yes, I did get the fan but haven't put it in. The GF wants her new bedroom finished before I can tinker with the DC lol. Glad to see you got it working! I plan on doing before/after temp measurements too see if there are any issues. The noise reduction sounds promising! As long as it cools enough we should be good . The fact that the fan is readily available doesn't hurt at all either.

 

I don't think the video does it justice, but when I have them on at the same time the difference is night and day.

I also attached my stl file for anyone who would like to 3d print the latch I made to accommodate the bracket and 40mm fan. I also needed to cut a small piece of metal on the gdrom mount in order for the fan to fit in the black case, which I didn't need to do in the white one.

 

Awesome that finally figured out some kind of a solution for this =)
Next time I take a trip to my local electronics shop I'll see if they can print these for me to try out too.

 

I'm now intrigued by the Noctua fan. It seems to be the best solution. As for cutting metal, the fan I was using is a 6.75mm thickness fan (Noctua is 10mm) . It appears 10mm will not fit on my VA1, so that might explain that. Is your white DC a VA0?

 

It is a VA1, but it was a very tight fit. The first fan bracket I printed was a lower infill so it deformed a bit more than the one I made for the black Dreamcast.

 

Tangentially related question: would it be feasible to have a passively cooled Dreamcast if you were to re-case it? I've got a GDEMU and PicoPSU in my system and was thinking the whole thing could fit in a case around half it's current height (probably limited by the GDEMU), but that would make the space situation for fans even worse than it already. But maybe if a metal case were to act as a partial heatsink, the temperatures wouldn't get too bad? Anyone know which parts output the most heat?

 

If you got a picoPSU, then I'm fairly confident the majority of the heat you get comes from the CPU/GPU.