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Re: 12v fan on 5v supply?

DigitalVT
Guide

12v fan on 5v supply?

Just received my pair of Noctua NF-A4x20 FLX fans I intended on replacing the stock ones to reduce the noise of the refurbished switch I've just bought, which I waited until I received it to check the fan size and voltage before ordering these.

 

Just connected the Noctua in them, fired it up to check which way the fan blew, and it didn't turn at all, plugged the original back in and that works fine.  Maybe the pin config is different, so I checked the volatge polarity only to find 5V's on the pins?  How can this be?12v fan12v fan 

Model: M4100-50G-POE+ (GSM7248P)|ProSafe 50 ports gigabits fully managed L2 switch with PoE+
Message 1 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

Hey did you ever get anywhere with this? I have the same switch and did the same thing - opened it up, saw the 12v fans and ordered the 12v noctuas which spin up for a second or 2 then stop.

Checked the voltage and it's putting out around 6v.

Opened up a GSM7248 and it had one of the exact same stock fans but that switch was putting out 12v from the pins. If I try that one in the M4100 it runs no problem.

If I try the noctuas in the GSM7248 they run and stay running and no fan fault light.

Should I just try the 5v versions of the noctuas instead?
Message 2 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Hi, 

 

wouldn't recommend the 5v Noctua either.  I think where your getting the 6v is that the switch is just sending a lower voltage to have the fans run at a minimumal speed.

 

I even went to the expense of getting another set of 12v fans, think they were noiseblockers, and they didn't work! I got so frustrated, not only having to disconnect, take the switch out of the rack, take apart, that I sensed the wiring colours differentiate from all the others from the stock fan that Netgear phase reverse somewhere, anyway, cut a long story short after many variations I think I blew the 12v power rail.

 

so bought another switch off eBay, probably easier and cheaper than sending this for repair.  Noticed an American eBay seller selling fans for the Netgear switch.  He wasn't very forthcoming as to what voltages were where and what fans he's using and his prices are expensive and cost of shipping and import fees, I headed over to Aliexpress and have bought a selection of 3 or 4 fans that maybe suitable and should cost the same if not less than our US eBay guy.  When they come in from China, I'll let you know, may have spare fans available!

Message 3 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

Let me know how you get on. The noctuas spun up in the GSM7248 when the positive and negative were reversed. I've ordered some 5v noctuas to try the same thing with reversing the pins.

Have seen the US seller on ebay as well but the cost plus shipping seems extortionate and no mention of what the noise output may be with those fans fitted.

I have so much Netgear kit I'd prefer not to have swap out equipment for other manufacturers and spend even more money, but the way they use fans in each device seems pretty strange.

I've made the same mods with other dell, hp and cisco switches and not had any problems like this.

Would be very interested to hear what results you get with the new fans.
Message 4 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Ordered the fans after i bought the latest switch on eBay, fans were shipped on 9th Jan via Aliexpress shipping, so in theory should be here at the end of the month.  I'm now living in Dublin, so opted for the eBay "International shipping", even though its shipping from the U.K., I reckon the parts from China will be here before that gets here.

 

The Netgear switch replaces a Ubiquiti PoE switch which went bad not even after two years, never going to buy Ubiquiti again (had a Unifi G3 filter stick as well!).

 

id be interested in what you consider the pin (voltage) configuration, am so confused with Netgear and Noctua differing configurations?

Message 5 of 25
schumaku
Guru

Re: 12v fan on 5v supply?

Can't see anything strange - except of that people try to put in replacement fans able to create a light airflow (40% less than the 5000 min^-1 Delta fan variant, max rotation speed 5000 vs. 13000 making less than 25% of the max airflow, and some 85 of the max air pressure). How easy it is to build a "silent" fan at these limitations (lower fan tip speed - this is whee most aerodynamic noise is coming from). In my opinion a fan not fit for replacing in any of these switches, even if it rotates, and the Fan error LED does not go on.

 

If an amateur aircraft builder would ask me if this engine and propeller combination ("hey I found a sooo silent solution and my Piper L-4 with it's Conti A-65 flies great") would fit his next project designed for a much bigger engine and better prop, he will hear that the takeoff run over 50 ft obstacle will be much longer, the max rate of climb will be nuts, and last but not least the cruise speed will be poor. Overall, doing so would be a major safety risk, and I'm most likely unable to sign-off his project powerplant. 

 

The FFB0412SHN nominal 12 V models have a rated operating voltage range from 4.5 to 13.8 V as per the specs - so 5 or 6 V voltage is OK. As @DigitalVT mentioned, this lower "cold switch" fan voltage is certainly implemented this way to allow lower minimum rotation speed - and it will come up to higher voltage if required. Depending on the Noctua fan motor design, it's well possible that the fan does rotate easier in the non-intended rotation direction. For example small classic DC brush engines (think of what Mabuchi builds in zig millions of and millions of one model every year) are timed to rotate in one direction for ideal power output including the torque. To let them rotate backwards, a much lower voltage is sufficient, but power out and efficiency will be ways below. And yes, several Mabuchi can be ordered from the factory for alternate rotation direction, and many can be re-timed by bringing the brushes for it. Enough said on this excursion here. 

 

Note: There is absolutely nothing wrong with the Noctua fan design and specifically the NF-A4x20 (FLX just designates the add-on electronics for interfering even more) - if is deployed where the massive lower cooling capacity of the airflow is acceptable - they just can't replace any FFB0412 variant.

Message 6 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Am sure the stock Netgear fan is great for switches in an enterprise scenario where the switch is under full load, speaking for myself, just want a switch with enough ports that can accomodate various connectivity around the home without additional switches elsewhere or having to manually repatch, thus the device itself wouldnt be under much load, therefore a slight breeze from these quieter fans may be enough to keep the Netgears internals cool enough to be accpetably quiet in a home environment?

 

I've got 8x PoE cameras, 3x PoE AP's, a PoE Cloudkey and multiple wired ethernet devices.  My thoughts that a Noctua or other "quiet fan" running at 100% capacity keeping the internals cool when the switch is not busy and then may take longer to cool for the "short" busy times, is an acceptable useage, giving a quieter environment?

Message 7 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

@DigitalVT Did you ever make any progress with this?

Message 8 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Hello pn23,

 

sadly still waiting for delivery.  It's been two months tomorrow since I ordered it, the tracking mentions it arrived in destination country on 15th Feb and on the 22nd Feb it was accepted by the last mile courier.  Have received two items I've ordered weeks after, and many other items have also followed in the black hole/depot these fans are sitting in.

 

Maybe this week?  But have been hoping that for a number of weeks!

Message 9 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

The fans arrived today!! pn23, your post must have got their attention!!

 

Received 7 fans, 3 pairs and an odd one.  Guess I didnt get 4 pairs when ordered!!

 

This version of GS752TP has the fan connectors underneath a board, so not as easy to swop fans over.

 

I've tried all 3x of the new pairs and not one fired up.  When I tried the fat SunAce40 (theyre almost 30mm deep), a little smoke came from somewhere, so pulled the power quickly.

 

Don't understand why Netgear fans are wired differently to ALL Other fans.  I presume I need to change the polarity.  But why?  Netgear, WHY?  Guess I've gone through a pair of Noctua, some others and now these!

 

Can someone just clarify the pin conguration, polarity for me please?

 

The Netgear stock fans, looking from top, left to right are - Red - Blue - Black

 

The others i have are - Black - Red - Yellow.

 

Your help would be apprecaited.  Many thanks.

 

 

 

 

Message 10 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

Hi @DigitalVT 

 

I am using a GSM7248Pv1h1. The stock Delta fans that are in it are red (+), black (-) and blue (sense/tacho)

 

I have tried a few different manufacturers of coolers that match the spec for voltage, current, power, starting voltage etc and they all do the same thing - spin up for a second then stop.

 

Sunon and others use yellow wires for the sense pin, and the red and black remain the same as you'd expect. When trying Noctua fans, I'm pretty sure I had to reverse the +/- pins as they were the other way around on the switch, but it's been a while since I did that so I could be wrong!

 

I have also tried different fans in a GSM7248. That device has 3 fans. Trying new fans on the headers for 1 & 2 did the same thing, spin for a second then stop, but when I tried a new fan on the header for 3 it worked. The stock fan connected to 3 was 20mm deep, the ones connected to 1 & 2 were 15mm deep, but the fan on 3 was the noisest. Whether stock or not, it seems to run at full tilt from power on, and having the sense pin connected or not made no difference at all. It is deafening.

 

Some of the stock fans may have onboard controllers or dependant hardware that the switch may be looking for and if it doesn't see them, cut the power I guess.

 

I'm going to keep trying when I have time, but may eventually have to call it a day and get rid of them and drop in some silent HP equipment instead. Shame really as I have mountains of Netgear kit and would prefer to stick with one vendor.

Message 11 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Well, my replacements, havent spun up.

 

I suspect when yours have spun up, it was on the initial power up and then the temperature sensor noted the temperature was low enough that the fans could idle, and lowered the voltage, hence why yours stopped spinning as the voltage wasnt enough for those fans?

 

My predicament is that the colour coding on my old ones don't make sense, you'd think it would be standardised.  See picture, stock Negear fan on left, new connector on right.  My OCD is saying that Red and Black are positive and negative.  And the Blue and yellow are the sensor.  But the pins all move about!!

 

IMG_4846.jpeg

Message 12 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

I agree with you. 

 

I would pop the pins out on the new fan, stick the yellow one in the middle and then with the connector of the new fan facing the same way up as the old one (not as in your last picture) swap the red and black around.

 

I've tried quite a few now and the cabling on the left is definitely correct for v+, v- and sense.

Message 13 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Thanks pn23.

 

Would you then agree with the pin config as overlaid on the right plug in the following pic?

connectors.jpg

Message 14 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

Yes, that's how I've done every one I've tried.

 

They've at least spun up, but then stopped after a second.

Message 15 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Success.  The Pin config has worked.

 

The two pairs of 20mm deep fans span up briefly and then stopped, like your others.  But the deep 28mm work full time.  They are noisey!!  Having said that, the volume of air they pass is incredible!  Nothing is going to get warm inside of here!!  I'd almost consider just running one!  The noise level is about 55db about half a metre above!

 

Just having issues, logging into the switch.  Will report back if I can control them!

 

SunAce40.jpg

Message 16 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

Good work!

 

I'd be surprised if you can control them though. The originals I have in mine run at around 55db each as well and the speed never changes.

Message 17 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Well, these are the ones that worked.  They do spec 40db per fan.

 

https://www.aliexpress.com/item/32381567224.html?spm=a2g0s.9042311.0.0.27424c4dkENqYg

 

I've just updated the firmware and now not a peep out of the network ports.  Smiley Mad

 

Am going to give it a rest for a few days...

Message 18 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

Hey @DigitalVT did you manage to get any further with this and were you able to resurrect your switch?

Message 19 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

Hi pn23,

 

Yeah, the fans installed okay.  My switch issue was that when I did the firmware update, I guess either it performed a factory reset or I did and came back on the default IP address (192.168.0.239), which is not in my subnet (172.16.0.x).  So couldnt see it.

 

So it is back and working, but noisey, still, even louder in the rack case!!  So back to square one.

 

Was considering the new line of Netgear switches, but don't have any cash to spend at the moment!

Message 20 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

pn23, did you progress purchasing a replacement fan yet?

Message 21 of 25
pn23
Aspirant

Re: 12v fan on 5v supply?

Yeah, other than the Noctuas, I have tried Sunon HA40201V4-1000U-G99 (3 wire with RPM/tacho feedback) and Sunon MF40201V3-1000U-F99 (3 wire with locked rotor detection) and had no luck. Same behaviour as all of the others, they spin up for a second then stop.

 

I'm completely stumped.

Message 22 of 25

Re: 12v fan on 5v supply?

I found this on the Noctua web site.

 

https://noctua.at/en/what-pin-configuration-do-noctua-products-use

 

 

Message 23 of 25
DigitalVT
Guide

Re: 12v fan on 5v supply?

It's been a while since I tried them, but they didn't work with various configurations.  Unless you've tried otherwise?  Thanks.

Message 24 of 25

Re: 12v fan on 5v supply?

Ya know, ya'all could have solved this by just leaving the case of the switch open and buying a plain old 120v desk fan with a large diameter blade, and setting it to turn slowly and point at the switch circuit board.

 

it sounds to me like none of you either read or understood the earlier post that made the connection between airflow, rpm and noise.

Message 25 of 25
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