How can I undervolt these fans...? A unique scenario.

WATYF1 · Post by **WATYF1** » Thu Feb 20, 2003 10:05 pm

OK... This is the deal.

I bought this Koolance case, and planned on building my first completely silent system.

The case has 3 80mm fans built into the top. I assumed right off the bat that these fans would be louder than I wanted... and I was right. So the plan was to buy 3 80mm Panaflos and replace the stock fans with the Panaflos. So I did that... everything seemed fine.

The Koolance case runs the fans at three speeds. 1) Low speed until you hit 45*C, 2) Low speed until you hit 35*C, or 3) High speed all the time.

So I assumed that I could just pop the Panaflos in, and it would undervolt them on settings 1 and 2, and run them at full speed at setting 3.

Well... it didn't quite work that way. What happens is... it won't do anything on settings 1 and 2, and it runs them full speed on setting 3.

I noticed that while installing the Panaflos that they had a 2 pin connector. I thought that was a little odd, and I had to chip of the little tooth on the connector to get it to fit in the 3 pin socket. Now... the original fans had a 3 pin connector, but only two wires were in the connector, so I was hoping that there wouldn't be any difference between the original fans, (3 pin connector with only 2 wires) and the Panaflos (2 pin connector, 2 wires). But obviously there is a difference... I just don't know what it is.

I read somewhere that the 2 pin connector has different traits than a 3 pin, (other than the whole "one less pin" thing.

) Is this true? Should I have gotten 3 pin Panaflos? Would that fix my problem?

My other solution is to undervolt the fans while they run at the full speed setting. So... if I have to do that, what's the easiest way to drop the 12v connectors down to 9v or 7v? I'd rather not use a rheostat, if at all possible. I know there are options for just using "rigged" connectors to do this, I'm just wondering what my best options are.

Any suggestions would be appreciated. I'm kinda thinking that the whole "2 pin" thing is the cause of the problem, because the fans I replaced were just normal 80mm fans... nuthin' special... so I would have assumed that the Panaflos would have worked just the same... but alas.. they don't... so do I need 3 pin panflos, or a voltage regulation?

WATYF

Justin_R · Post by **Justin_R** » Fri Feb 21, 2003 12:17 am

Check out the SPCR Recommended Fans page for a discussion of the different kinds of fan power connectors.

I doubt the connector itself is the culprit here. If the fan is getting powered when the Koolance drives it at full voltage, then the wires are hooked up correctly. The likely culprit here is that whatever voltage the Koolance runs the fans at for it's "low" setting is insufficient to start the Panaflos. Most Panaflos will start reliably at 5V, so I guess the voltage the Koolance provides is less than that. If you're really adventurous, there's probably some way to change what voltage the "low" setting runs at, either simply (some kind of potentiometer that you can adjust) or difficultly (swapping out a resistor). You might want to e-mail Koolance and ask them what voltage the fan lines supply when they're in the "low" setting, and if there's any way to change it. Most Panaflos will run at 5V, so if the Koolance provides at least that, they should work. This would be the best solution, as it allows you to keep the thermally activated fan speed changes.

If the Panaflos kind of twitch when you first turn on the power, but don't spin, then you know that they aren't getting enough voltage. Before you go to the trouble of creating that "rigged" connector, you can quickly make sure your Panaflos start at lower voltages by hooking them up to the 5V and GND lines of an IDE connector using small lengths of wire. If they won't start at 5V then you got unlucky Panaflos. If they also won't run at 7V, then you got really unlucky Panaflos.

One thing that I ask only because of this post is: are you sure that they are 12V Panaflos and not 24V?

WATYF1 · Post by **WATYF1** » Fri Feb 21, 2003 6:23 am

OK.. thanks for the tips. I'll try some of that stuff out.

As for the Voltage... I'm pretty darn sure that they're 12V. I found them by searching for the specific model number, so I can't imagine that they'd be 24V's, but I'll double check. One thing is... I bought them from an Electronics store... not a computer store, so who knows... maybe they are 24V.

Another thing I should have mentioned... this is odd. When I found out that they wouldn't run at low speed, I plugged on of the old fans in, while the Panaflos were still plugged in. It ran at "low" speed (obviously), but I also noticed that the Panaflos were starting to move a little. They barely had any RPM's, but they were moving. So... when just the Panaflos are plugged in, they don't do a thing,... no "twitch" when it starts up.. no nuthin'... but if I plug one of the old fans in along with the Panaflos, then they at least try to move... and sometimes do for a little bit. (at very low RPM's).

WATYF

seishino · Post by **seishino** » Fri Feb 21, 2003 8:19 am

It sounds like the koolance is using the fan speed monitoring line to regulate speeds. If you plug in another fan, that monitoring line should be getting some sort of feedback. However, if your panaflo has no designation in the serial number after the 12L1A part, you will have no feedback at all. That might explain why the no-speeds settings.

On the other hand, it might also be a mounting problem. I'm looking at a stack of Panaflo 3-pin adapters here and I see that

[p=Power Line] [Red on your model]
[Blue on your model]
[M=RPM Monitoring Line]

P B M
goes to
M P B

on a standard 3 pin.

Your two pin, on the other hand, goes from

P B [Empty]
to
P B

So, it should mount in the second spot over, so that the Red wire is mounted to the middle pin. Make sure the little plastic nubs are in the same direction as the plastic nubs on your original fans.

You can tell all of the specifications of the Panaflos by the model number on the front. They should be FBA08A12L's, with the 12 designation being the voltage. If it says 24 anywhere, it's the wrong kind.

I have a bunch of 3-pin panaflo tails here. If you want to try one, just e-mail or PM me your address and I'll drop one in the mail. I do think the lack of RPM monitoring might be the culprit, which might be rectified by configuring the device which is controlling fan speeds. What, BTW, is that thing controlling the fans? Does it have a serial / model number / manufacturer on it?

edit: One of these days I'll learn to spell monitor.

WATYF1 · Post by **WATYF1** » Fri Feb 21, 2003 10:16 am

seishino wrote:It sounds like the koolance is using the fan speed monitoring line to regulate speeds. If you plug in another fan, that monitoring line should be getting some sort of feedback. However, if your panaflo has no designation in the serial number after the 12L1A part, you will have no feedback at all. That might explain why the no-speeds settings.

I think you may be right... and if that's the case... then I can't use Koolance's built in fan speed control, because when I plugged in one of the old fans, and it lowered the fan speed of the Panaflos, they almost barely turned at all.

Which means I need to control the panaflos by some other means... so... what's the easiest way to do that?

I've got three 2 pin panaflos that I need to undervolt to 7v (since that seems to be the popular setting). How do I go about doing that? I'd prefer to be able to turn them back to 12v if necessary (if it ever gets too hot).

Any suggestions would be appreciated. Thanks.

WATYF

(btw, they're definitely 12V fans.)

1HandClapping · Post by **1HandClapping** » Fri Feb 21, 2003 11:31 am

WATYF1 wrote: I think you may be right... and if that's the case... then I can't use Koolance's built in fan speed control, because when I plugged in one of the old fans, and it lowered the fan speed of the Panaflos, they almost barely turned at all.

Which means I need to control the panaflos by some other means... so... what's the easiest way to do that?

I've got three 2 pin panaflos that I need to undervolt to 7v (since that seems to be the popular setting). How do I go about doing that? I'd prefer to be able to turn them back to 12v if necessary (if it ever gets too hot).

Any suggestions would be appreciated. Thanks.

WATYF

(btw, they're definitely 12V fans.)

It sounds like the fans maybe in electrically serial. The Koolance fan probably drains most of the voltage from the circuit. Try using one three pin Panflow to control the speed, instead of the Koolance.

WATYF1 · Post by **WATYF1** » Fri Feb 21, 2003 3:35 pm

OK... Well. I did some more tests...

The results are bad... and yet good.

It appears that all my other fans will run on Koolance's lower settings... the Panaflos are the only ones that won't. (go figger). That's the bad news.

The good news is that all my other fans, when run on the low setting, have extremely low RPMs. So low that they don't really push any air at all... which brings me to the conclusion that the Koolance speed control is not the way to go...

that said... it looks like I'm going to have to use some other kind of control to change the speed of the fans.

So.... I was looking at the BayBus. It looks like a relatively easy way to control all my fans. From what I understand, I can hook all three fans up to the BayBus, and just turn them up or down whenever I want to. If that's the case, then I would be willing to go that route. Does anyone here recommend anything other than the BayBus for an easy way to control a few fans? If not, then where's the best place to get a BayBus at... (in the US). I'm going to want a beige faceplate also, to go with it.

WATYF

WATYF1 · Post by **WATYF1** » Fri Feb 21, 2003 4:35 pm

Well... I think I'm going to get me one of these.

I did some reading and it appears that the best and most convenient way to control multiple fans is using a rheobus. There are two major models available... the Nexus, and the Sunbeam. But it appears that there are longstanding issues with the Nexus, as being reported on Anandtech and OCForums, so I'm gonna go with the Sunbeam.

I think this will take care of my problem.

WATYF

Justin_R · Post by **Justin_R** » Fri Feb 21, 2003 9:44 pm

seishino wrote:It sounds like the koolance is using the fan speed monitoring line to regulate speeds. If you plug in another fan, that monitoring line should be getting some sort of feedback.

I thought that might be the case, too, but then I read this part again:

WATYF1 wrote:Now... the original fans had a 3 pin connector, but only two wires were in the connector, so I was hoping that there wouldn't be any difference between the original fans, (3 pin connector with only 2 wires) and the Panaflos (2 pin connector, 2 wires).

So if the original fans are only 2 wire, then the Koolance can't be using the RPM sensing line for speed regulation.

I suppose it doesn't matter much anymore, but have you tried two original fans and one Panaflo? When you add one original, the only thing that changes electrically is that more current is being drawn by the fans in total. Maybe the total current draw somehow affects the voltage level being supplied.

Anyway, a rheobus will provide you with a pretty decent solution, but you may also want to try wiring the Panaflos directly at 5V or 12V. If you want a little mini-electronics project that will save you some cash, you can follow MikeC's directions for making a 5V/12V switch here.