Norco 3x120mm PWM backplane

Notice: Page may contain affiliate links for which we may earn a small commission through services like Amazon Affiliates or Skimlinks.

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
I'm a newbie to Norco cases bu wanted a cheap'n'cheerful backup server so been spending the weekend standing one up. It's a 3U 3216 badged as a Logic Case SC-316 that takes standard 2U PSUs and has a fan wall of 3x120mm.

I've replaced the fans with Noctua NF-F12 PWMs which are exceedingly quiet and provide good static pressure; however I've noticed they run at full pelt (~1500rpm) which isn't entirely surprising given that the hot-plug backplan they're running from is just plugged into a 4-pin molex and there's no connection to the motherboard.

However, I notice that, nestled right in the corner behind the molex, is a 6-pin plug (in a 2x3 configuration); I'm guessing that this might be to be some sort of PWM connection for the whole backplane - is anyone else her familiar with this and can anyone give any explanation of what this is and if there are any cables/splitter available to hook this up to the motherboard PWM header(s)?

(Server in the middle of a RAID rebuild at the moment but I'll take a snap of the backplane and header when I can - you can't see the connector from the pics on their website since it's down right at the bottom between the drive cages and the fan wall)
 

Aestr

Well-Known Member
Oct 22, 2014
967
386
63
Seattle
Not sure on the plug you mentioned, but typically I don't associate that level of complexity with Norco. Is there any reason you don't just plug the fans directly into your motherboard? If the cables don't reach or there aren't enough headers, there are extension and splitter cables that work well and don't cost much at all.
 

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
Design of the fan wall is such that the 4-pin header plugs into the outside of the fan caddy, and when this slots in, it plugs into the backplane at the bottom of the case (fairly standard setup AIUI). It might be technically possible to route the wire outside of the fan caddies and around the sides of the fan wall, but this would require some pretty massive extension cables (at least on the order of 50cm for the fan in the middle of the wall) and would ruin the whole hotplug aspect that the backplane was designed for.

Attached pic shows the best angle I could get of the setup - looking down from top (bright orange plastic thing is the rail to hold the caddy in place), this is with one of the fan caddies removed, you can see the four-pin PWM plug for the fan immediately above the molex connector, and the mysterious six-pin header is (unfortunately slightly shadowed) immediately to the right of that.
 

Attachments

Last edited:

Aestr

Well-Known Member
Oct 22, 2014
967
386
63
Seattle
Fair enough. I'm used to Supermicro where the fans have how swap housings that allow you to connect to the backplane or the motherboard.

Looking at the 6 pin header it doesn't seem like it would be for PWM control. That format would be a weird interface as you'd still need a cable that has a standard 3 or 4 pin fan connector on the motherboard end so I'd expect the same on the backplane to avoid weird proprietary cables. Without being able to see the tracing it's hard to speculate but I'd suspect they're either jumpers or a header for some other signaling.
 

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
I'm tempted enough to think about pulling out the backplane to have a look at the tracings, or even just to get some model numbers to see if anyone else has encountered such a thing - either my google-fu is weak or no-one else has cared enough to find out what this is...

Into the realms of optimistic educated guesses here but I thought it possible that three pairs of pins might relate to the sense and control lines for each of the three fans, with the molex providing the 12V and ground for all three fans - and thus it might be possible to split the sense and control from a single mobo PWM header into providing sense and control for all three fans on the backplane - but figured if that were the case someone might already have made such a cable...

And this, children, is why you should always see what documentation is available before you hit the "Buy" button!
 

Aestr

Well-Known Member
Oct 22, 2014
967
386
63
Seattle
And this, children, is why you should always see what documentation is available before you hit the "Buy" button!
lol it's tough with Norco and their resellers though since documentation is not something they seem to care about. I think your best bet is to pull the backplane and take a look. Almost certainly the reason you can't find is not weak google skills, but just nobody asking. The fact that your fan setup is different than the Norco branded solutions limits your chances even further.

You're not wrong that it's conceivable that they made the headers for that very purpose, it would just be odd they don't sell the cable, but stranger things have happened. Hopefully it works out, but either way let us know what you find when you take it out (and we know you will because it's going to eat at you not knowing:D)
 

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
Yeah I'm also used to documentation that comes with pinouts and suchlike but I can't justify the (5x! :O) cost that the supermicro chassis incurs in this environment. Worst case I have to make do with slightly more noise and wear on the fans if I can't get them to behave nicely, and miss out on the chance of finagling a nice hddtemp-to-pwmconfig script. Best case I'll borrow a multimeter and maybe even terrify SWMBO by attempting to wield a soldering iron.
 

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
Well so I unscrewed the rails that were holding the fan backplane in place - no ICs present, just a marking of 12038 on the PCB (which maybe just means 120x38mm? Who knows).

Good news is that yes, the PCB traces do seem to lead from each pair of pins to pins 3 and 4 of the fan connectors (with pins 1 and 2 being hooked to the much fatter ground and 12V lines coming from the molex) so it does seem that this header is intended to be used for PWM control of the three fans.

I'm thinking that if I try some female -> female jumper cables I should just be able to plug direct from a mobo PWM header and into the fan backplane to check it out, then assuming that works I should be able to join them up and have all three fans on the fan wall hooked to a single PWM header on the motherboard.

I'd be much obliged if anyone can tell me the correct names for these terminal blocks since a quick shufti at Farnell has got literally hundreds of the things... not much of an EE if you hadn't guessed already!

From some combined experimenting and looking about it seems that all the moetherboard stuff uses 2.54mm-spaced connectors so I guess that I need is something like this for the PWM header and something like this to plug into the connector on the fan backplane...?
 
Last edited:

Lennong

Member
Jun 8, 2017
119
24
18
47
Pulling the amperage/wattage for all three fans from one fan header is normally not recommended. I would use only one fan pulling both power and pwm from one motherboard header and the other two only the pwm signal from that same header. The other two fans you can feed the power from any 12v source as they will be controlled by the pwm signal anyway.
 

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
The power for the fans is already coming from a bog-standard molex, not the motherboard. My plan is to hook up a cable in such a way that the sense and control lines from a fan header on the motherboard can be used hooked up to this 6-pin connector on the fan backplane. Since the sense and control lines aren't carrying any significant of power I don't think it will be a problem for the reading from a single PWM mobo header to be used as the sense and control line for all three fans (although happy to be corrected on this).

More detailed pic of the business end of the fan backplane attached. The two large power line tracings can be seen coming off molex and line up with pins 1 and 2 on the fan header on the right. Tracings can be seen coming from the 6-pin connector, and one of each of the three pairs terminates under pins 3 and 4 at each of the three PWM connectors.
 

Attachments

  • Like
Reactions: Aestr

Lennong

Member
Jun 8, 2017
119
24
18
47
Aha, then I better understand your intentions. Yes, that sounds sound. There might possibly be a need to have some kind of power draw from the header for it to respond with feedback but on that I'm not 100% sure.
 

Aestr

Well-Known Member
Oct 22, 2014
967
386
63
Seattle
Very cool! It's a bit of work, but it shouldn't be too tough to make a 6 pin head to 3 PWM fan connector cable. You can just find an appropriate ribbon cable and crimp pins on the other end, or if you're happy to solder than crimp hack up the ribbon cable and a few PWM extension cables.

Keep us up to date on getting this to work!
 

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
If I'm understanding PWM correctly, the input voltage is constant and the fan itself sets the speed via the shape of the control signal, so fingers crossed as long as that stays intact across three connections it should be OK.

Current plan is to butcher one of the extension cables that came with the fans and connect it to two of the pins to serve as proof of concept.
 
  • Like
Reactions: Aestr

hybridchemistry

New Member
Aug 11, 2016
2
0
1
35
Dead thread arise!
Did @EffrafaxOfWug ever find a good solution here? I'm currently building up a 4220 and figured the case would have come with some sort of pigtail to plug into the motherboard or a controller, but no such luck. Better yet, if someone else has another solution, I'm all ears :eyes:
 

Aestr

Well-Known Member
Oct 22, 2014
967
386
63
Seattle
The backplanes for the fans in his case actually had a very neat set of header pins where you could control PWM fans. Does the 4220? If not the 120mm Norco fan wall is quite popular as it allows you to use nice quiet fans that still move decent air. It's just a dumb metal housing, so you can connect the 3x120mm fans you use (preferably PWM) directly to the motherboard.
 

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
DIE NECROMANCER SCUM!

...and in the real world I bodged together a crappy cable held together with electrical tape, but my theory worked - the fans in this case now hold stable at about 1000rpm, enough to keep the HDDs and other components like totally chill mon. The only reason I've not updated this is because:

a) Reading the speed reading from all three fans at once doesn't work - I only need to read from one of the three fans TBH. Otherwise the PWM logic occasionally gets in a tizzy and cycles between reading ~800 and ~1200rpm (note that this is only the fan speed read - the fan speed itself is actually consistent across all three fans. But if you have a script reading the fan speeds as reported you'll get a crazy amount of variance)
b) My soldering skills totally and utterly suck and posting a pic of my miserable failures so far would result in being banned from the internet
c) Actually plugging the 2.54mm connectors in to the fan backplane resulted in me nearly starting World War 3; even with tweezers and Orbital-style headband torches it was nigh impossible to actually mount the 2-pin connections
d) The current concoction of wire and tape is working fine, but looks a bit shit, so I've not wanted to post it up here

As to whether the 4220 has the same sort of PWM backplane...? I'd be highly curious to see since I've always wondered if the fan backplane pictured above was present in the US models, or if it was a UK/EU quirk.
 
Last edited:
  • Like
Reactions: Aestr

hybridchemistry

New Member
Aug 11, 2016
2
0
1
35
@Aestr - Yes, there are the 6 (3x 2 pin) headers next to the Molex connector in the 4220 case I have, using them would be great for PWM

@EffrafaxOfWug - Mors solum initium est! I'll raise another, don't tempt me!
But really, if we could get the pinout and orientation, that would be super helpful! I think for now I'll have to shelve adding PWM to the fans - and I just realized the stock fans I have in there are only 3 pin - but fan speed would be nice none the less.

See this is why I keep so much eWaste hanging around; you never know when you might need a ribbon cable from some case power switch or USB headers to hack into a pwm pigtale. Maybe eBay has a silly simple solution...

Edit:
BOOM: 610pcs Dupont Wire Jumper Pin Header Connector Housing Kit + M/F Crimp Pins 702921737873 | eBay + some ribbon cable you have lying around, and heat shrink if you want to be ~fancy~

Double Edit, final answer:
Don't bother making your own damn cables, use something pre-made and get it in 2 days:
https://www.amazon.com/SIM-NAT-Breadboard-Arduino-Raspberry/dp/B06XRV92ZB
Bless Amazon and Bezos.
 
Last edited:

EffrafaxOfWug

Radioactive Member
Feb 12, 2015
1,394
511
113
Am I to assume then that your (presumably USian?) 4220 does have a similar fan backplane...?

Pinout on the pics above was super-simple* and, after a bit of experimentation, turned out to be as I surmised - assuming you have the same connector with the 2x3 2.54mm dupont connectors laid out like the following crude ASCII;

Code:
   Fan header

   Fan header

   Fan header

MOLEX x x x
MOLEX y y y
The X pins correspond to the signal from all three fans, the Y pins correspond to the PWM control to all three fans. I combined all three of the signal cables on pin X into one, but as far as I can tell there wasn't any need to do so - sense signal from one would have done. Hence I don't think the X pins needed combining, but the Y ones do so as they all get the same PWM signal.

* I could have been wrong in the notes as I might have been slightly drunk** at the time and I don't have a multimeter...

** Whisky makes up for not having a multimeter, in fact it makes up for a lot of things!

*** In any case I must have worked it out by reversing the polarity, because it works for me now, so if it doesn't work just swizzle it around or something

**** This is not legal advice nor even advice that has driven past a legality farm
 

Dodd

New Member
May 7, 2020
2
0
1
So, while I've had this 4216 case for years, I have only just now installed guts in it, and was wondering if a connector had been made to do this? My thought was to try to connect it to a fan control hub? Has anyone done a pin-out diagram, preferably with photos? Or a diagram?

Please and thank you.