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nkourtzis
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Fan installation in RB1100AHx4

Mon Oct 30, 2017 3:21 pm

Hello,

I just got an RB1100AHx4 (NOT the Dude edition) and I see there are fan grilles in the case and a 2-pin header. Since I will be running the router overclocked and on a mountain, I wonder if I can install a 3-pin 5V 4x4x2cm fan in the case. I am thinking about this one: http://noctua.at/en/nf-a4x20-pwm

Any help will be greatly appreciated.
 
nkourtzis
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Re: Fan installation in RB1100AHx4

Sun Nov 05, 2017 1:01 am

Anyone?
 
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skylark
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Re: Fan installation in RB1100AHx4

Mon Nov 06, 2017 8:52 am

Hello,

PCB do not have any FAN controller, but you can add FAN to 5V and GND, then he will always be ON. I have not done it by myself, but it should work.
 
ste
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Re: Fan installation in RB1100AHx4

Mon Nov 06, 2017 10:30 am

Hello,

I just got an RB1100AHx4 (NOT the Dude edition) and I see there are fan grilles in the case and a 2-pin header. Since I will be running the router overclocked and on a mountain, I wonder if I can install a 3-pin 5V 4x4x2cm fan in the case. I am thinking about this one: http://noctua.at/en/nf-a4x20-pwm

Any help will be greatly appreciated.
RB1100AHx4 uses slightly less power than RB1100AHx2, has a heatsink and a broad temperature range. I would solve this external. So mayby you omit the housing of the RB1100 or add some holes to it and put it into a a big ventilated box.
 
dot02
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Re: Fan installation in RB1100AHx4

Sat Apr 15, 2023 1:48 pm

Hi, just a quick question as I was also planning to add a fan to the enclosure of my RB1100AHx4's: on the PCB tabs labeled "FAN", there is no voltage whatsoever (I was expecting +5V as labeled). I read above that the PCB doesn't have a fan controller, which is not a problem, but why is there no output voltage on the FAN terminal? are these pads not disconnected from a +5V power source somewhere on the PCB or is the voltage to this pins set to OFF on the software side?

Is there a command on ROS7 to turn on power delivery to this FAN pins (if it's software related) or a jumper to set somewhere on the board if it's related to the PCB design?

I wanted to avoid a separate power supply just for the fan as having it powered from the mainboard would enable the fan to take advantage of the multiple power redundancies the RB1100AHx4 has.

cheers
Denis
 
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rextended
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Re: Fan installation in RB1100AHx4

Sat Apr 15, 2023 1:55 pm

I haven't checked myself, but if there is no fan controller, why would there be voltage on the pins?
Otherwise, if there was, who would regulate the output on the pins if they would be permanently powered anyway?
 
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Re: Fan installation in RB1100AHx4

Sat Apr 15, 2023 4:10 pm

Well there's a big difference between both approaches. A fan controller has some logic to drive and control the fan (temp control, fan RPM monitoring, etc.). And it has been made clear that the PCB doesn't have that, and that's perfectly fine.

This doesn't mean that the board couldn't have a simple voltage regulation to supply 5V to the fan pins. That's really extremely easy to implement (when it is taken into consideration during the PCB design) and comes at almost zero cost (we're really talking about way less than 30c worth of components). It would have no fan rotation or voltage monitoring, just supplying basic voltage. So I was wondering if this has been implemented, especially since the FAN pads are already present on the board (that means that someone has thought about it during the design phase)

(basically: if the fan has 3 wires, chances are pretty high that there is a fan controller onboard whereas if the fan has only 2 wires, it's just a simple voltage supply, period)
 
pe1chl
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Re: Fan installation in RB1100AHx4

Sat Apr 15, 2023 9:41 pm

Probably the situation is that "there is no FAN controller" means "it is foreseen on the PCB but not populated for this model to save some cost".
Of course you can get voltage for the fan but you need to look for the PCB position where the FAN controller could be, and bridge some connections of a switching transistor/fet position (that is now empty).
 
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Re: Fan installation in RB1100AHx4

Sat Apr 15, 2023 10:13 pm

okay, in that case, that may not be worth the trouble just to add a fan. If the router is sold fanless and there are no feedbacks or complaints about hardware failures, I think I'll leave it as it is and forget about it.
If the designer of the board reads this, however, feel free to drop in :)
 
pe1chl
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Re: Fan installation in RB1100AHx4

Sat Apr 15, 2023 10:21 pm

when you have it open anyway, make a hi-res photo of that area of the board and put it here...
 
dot02
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Re: Fan installation in RB1100AHx4

Fri May 12, 2023 4:22 pm

Here are the pictures:
Full board:
board.jpeg
Power section detail:
detail.jpeg
now, after several tests, I would suggest not to tap one of the DC input PSU's connectors (the white ones). Even though it supplies 24VDC with more than enough current to power bith the board and the fan, these 2 inputs are isolated against each other, meaning that if you have conected your fan to input one and it fails, then your fan will stop working even if PSU2 is still supplying the board.

I found 2 viable options where you can connect a fan:
1) next to the DC input 2 connector, below the C105 cap you have 2 tap points (just above the D100 diode). These taps provide 24VDC no matter if PSU1 or PSU2 is powering the board. (+ is on the connector side, so on the right). Careful however: if you power your board throuch PoE, you will see +48V on those pins!! So basically, these pins have the voltage of the highest voltage of any of the board's active power supplies. So you should use this solution ONLY if you power your board via the built-in power supplies OR PoE OR Telco 48V. BE CAREFUL!!

2) probably the best solution (but I didn't test it yet because I don't have such fans at hand) is to tap of the voltage on the pads C113 next on the top right cornet of the transformer. These pins have a 5VDC output no matter what the board's supply is. this is the main 5V voltage bus of the board, which is filtered via the gray/pink cap just next to it, and also re-regulated to various specific voltages on many other places on the board. Be careful however, I would aim for a 5V fan with the smallest wattage, just to be on the safe side and avoid any possible disturbances.

I have ordered a couple of 5V 30mm x 30mm x 10mm fans (6mm thick fans would be even better) and will report when I have it working...

Disclaimer: If you damage your board, hurt yourself or kill your dog, it's your fault, not mine! If you open up the enclosure, you agree to take full responsibility for anything that might happen including injury, death, or even a pink dinosaur knocking down your front door and eating your family. Remember that if Mikrotik sells the device without fans, it means that it doesn't need any fan! And these boards are installed all around the world and seem to be running fine without any fan!
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dot02
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Re: Fan installation in RB1100AHx4

Fri May 12, 2023 9:26 pm

OK I found a fan in my garbage. Sunon MF30060V21000UA99 (30x30x6mm)
connection.jpeg
fan.jpeg
Works like a charm. For the moment the fan is blowing the hot air out of the case but it might be better the other way around. I will monitor it to see which way is better.

Enjoy!
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pe1chl
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Re: Fan installation in RB1100AHx4

Fri May 12, 2023 11:12 pm

Thanks for the pictures... did you check the 2 locations for transistors (or double diodes) near the 5V FAN connection?
Do they have 5V on some of the pins?
They could be related to the FAN pins, and the fact that they are not populated could explain why there is no output voltage on that connector.

For example, I have some older CCR1009 in use and they have 2 FANs, in the config one can select a primary and secondary fan, one is running and the other is started when the first one fails, and they are regulated towards 50 C temperature of the processor.
It could be that this unpopulated space was for a similar circuit with one fan (only temperature control)...
 
dot02
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Re: Fan installation in RB1100AHx4

Sat May 13, 2023 2:19 pm

These missing transistors look like a simple voltage supply regulation with no negative feedback so that the fan does not cause any interference with nearby circuitry. But it could also be for a LM7805 voltage regulator IC (also 3 pins)...That would require some advanced reverse engineering. Therefore I did not check that as I wanted a simple and easy solution, and wanted to avoid the potential necessity for soldering SMD components. Moreover, taping 5V for the fan there could have an impact on the UART outputs. It could be that some resistors in this area would need to be replaced with other values. This is clearly not worth the trouble. Having the fan connected to the main 5V bus near the noisy power section is easy, quite fool proof and good idea since the power is cleaned and regulated on subsequent stages anyway.

One thing is for sure: there is no proper fan control or monitoring, as there are only 2 fan pins. The monitoring could never see if the fan stopped working like in the CCCR1009 (I guess there are at least 3 cables to the fan)

However if cou could also post come pictures of CCR1009 boards, we could have a look if the circuit looks similar. Do you have the possibility to identify and measure the values of semiconductors?

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