Posted: Thu Aug 06, 2020 13:48 Post subject: WRT32x with 40mm fan
Hi,
I will start this post mentioning that I'm not an electrical engineer. I pretty much know how routers, networks and PCs work, but I don't have much knowledge to do "electrical" things.
I have a 40mm fan laying around (Noctua NF-A4x10 5V) and I was wondering if there is any way into soldering this directly on the router board.
Another way would be soldering a step down module from 12V to 5V and connect the fan to it. I know that the power supply of the router works at 12V 3A and I would need a step down module to transform 12V into 5V.
One thing caught my eye regarding the board: the serial port (UART) works at 3.3V, but I'm not sure what is the pin layout for those. Would this be enough to spin the fan? I know that using the 5V fan at 3.3V would lower the RPM. _________________ Linksys WRT32X - DD-WRT v3.0-r50551 std (10/19/22)
Linksys EA6300 - DD-WRT v3.0-r40167 (backup router if something goes wrong with the main one)
Thank you for your reply. I'm thinking now into getting myself a PWM to USB adapter and just use the USB port on the router. _________________ Linksys WRT32X - DD-WRT v3.0-r50551 std (10/19/22)
Linksys EA6300 - DD-WRT v3.0-r40167 (backup router if something goes wrong with the main one)
Hello,
This is what I use on Openwrt router wrt1900acs v2, at an ambient temperature of 28 degrees the router together with the nf-a4x20-pwm fan manages to have 47 degrees without a fan reaches 64-65 degrees.
Joined: 17 Feb 2010 Posts: 611 Location: Yorkshire (GOC)
Posted: Mon Aug 10, 2020 12:27 Post subject:
T-z3P wrote:
Thank you for your reply. I'm thinking now into getting myself a PWM to USB adapter and just use the USB port on the router.
That is the best way to do it. Just make sure you get the quietest fan that you can find, with some soft rubber feet. Low speed is fine if you go with a 120mm fan. _________________ Linksys WRT32X v1 - r45677
Linksys WRT1900AC v1 - r45677
TP-Link Archer C9 v1 - r45677
Firmware: ftp://ftp.dd-wrt.com/betas/2021/
I would not connect a fan to the 3.3v on the uart. Likely this cannot provide enough current to drive a fan, and also possible it is the same 3.3v source the rest of the logic on the board uses and you'll likely introduce electrical noise into the 3.3v rail.
The safest non-intrusive way to do this is go find some USB-A to USB-whatever cable you dont care much about, chop off the non USB-A end and wire your fan up to the USB power wires and plug it into the router's USB port. Set the fan on top of the router, maybe add some rubber feet if the fan vibrates at all that it eventually dances off the top of the router.
If you really want the fan inside the router, you could solder to the 5v power pins on the usb port, or add your own 12v to 5v regulator/buck converter to the 12v barrel jack connector.
There MAY also already be an unpopulated fan header on the 1900AC. The original ones did come with a fan, The later ones dropped the internal fan. I am not sure what voltage the fan was on the original 1900AC. You should be able to google teardown pics of the original one to find where the fan header was.
I've found the following image for WRT32x. The fan connector is still there and if you look closely, it is the same as in WRT1900ac (ignore the red circles around the case).
After seeing your post, I've opened the case of my WRT32x to look for a place where a fan might fit and found literally none that can help the router cool down. The only thing I can think of at the moment, would be to unscrew the big heatsink that can be seen in the right of the image from the previous post, take it to someone with a CNC machine and cut a place (in depth) to fit a 40mm fan (I will also have to get a 12V fan or a step down converter from 12V to 5V to use my existing fan). _________________ Linksys WRT32X - DD-WRT v3.0-r50551 std (10/19/22)
Linksys EA6300 - DD-WRT v3.0-r40167 (backup router if something goes wrong with the main one)
I've found the following image for WRT32x. The fan connector is still there and if you look closely, it is the same as in WRT1900ac (ignore the red circles around the case).
After seeing your post, I've opened the case of my WRT32x to look for a place where a fan might fit and found literally none that can help the router cool down. The only thing I can think of at the moment, would be to unscrew the big heatsink that can be seen in the right of the image from the previous post, take it to someone with a CNC machine and cut a place (in depth) to fit a 40mm fan (I will also have to get a 12V fan or a step down converter from 12V to 5V to use my existing fan).
Just because the header is there, doesn't necessarily mean all the other required support components are there for it to function. Since these fans are temperature controlled, they're likely switched on and off by a mosfet or transistor tied to one of the CPU's GPIO pins. If that mosfet or transistor was left off because the header wasn't going to be used, then it isn't going to function. To test, get your router nice and hot or adjust the fan temp thresholds under the services tab in ddwrt to something below your ambient room temp, then use a multimeter to see if 12v is present on that header.
I will start this reply by saying that YOU SHOULDN'T PROCEED LIKE I DID. I will also mention that I did 2 big mistakes which will be detailed below.
TL,DR: It didn't worked.
I've took apart my WRT32x and took of the main aluminum radiator to be modified ( https://i.imgur.com/v7n32Rl.jpg ). I've placed the fan over the aluminum radiator, traced some lines and started the process ( https://i.imgur.com/K0k0UHN.jpg ). This was my first mistake. I haven't considered that the fan will be half covered by the case. I should have moved it a bit further in to the back ( https://i.imgur.com/pIOKO6p.jpg ).
The cooling pads were replaced ( https://i.imgur.com/EnCTHiP.jpg ), then I measured the fan pins on the board and I got about 2.4V ( https://i.imgur.com/9cnZzde.jpg ) and I thought that the voltage will be increased when the temperature will reach the default of 65 °C. After that I've proceed with soldering a fan adapter and placing the aluminum radiator on the board ( https://i.imgur.com/IKaOw9k.jpg ). This was my second mistake. I haven't tested if the voltage is increased by lowering the default value for "High Temperature (FAN On)" from DD-WRT > Services > Services > Hardware Monitoring.
Conclusion: The fitment was just fine ( https://i.imgur.com/S5yNv2w.jpg and https://i.imgur.com/V2R8PFP.jpg ), but the voltage wasn't changing when the temperature limit was reached, so the fan isn't spinning. The next thing to try would be a step down converter from 12v to 5v to be soldered directly to the 12v power pins. That means the fan will run continuously. _________________ Linksys WRT32X - DD-WRT v3.0-r50551 std (10/19/22)
Linksys EA6300 - DD-WRT v3.0-r40167 (backup router if something goes wrong with the main one)
I have just wrestled the hardware resistor, bridge, capacitor and transistor, but the fan is not running, is this function active in the router or do you still have to start a service?
has something been newly integrated? Yes, I'll try it later, I have to open it again anyway because my 2 Chinese fans 80x80x10 failed, one after 3 months and the 2nd within a few days. Probably because of the sleeve bearings. Now I am going to install Sunon MagLev fans with vapo bearings because I haven't had a single failure in the last 20 years.