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Question Connect 4 pin fan to 2 pin header?

May 15, 2022
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The fan of my UPS is very noisy, so I was thinking of changing it for a noctua.
The problem is that the UPS header is 2 pin and the noctua fans only come with 3 or 4 pins.

Noctua NF-A6x25 PWM (4 pin)
Noctua NF-A6x25 FLX (3 pin)


Which one should I buy? and could I connect them directly to the header or would I have to do some mods?

Header image: View: https://imgur.com/u1S3coH

My UPS is a SMART1500LCDT Tripp lite (in case it could be of help)
 
It looks like a proprietary connector.
Without a third fan speed connector, the fan will run at max speed all the time.
You could try to construct a voltage lowering cable mod to run the fan at a lower 7v. or 5v.
https://www.techpowerup.com/articles/other/137

Or, better yet, modify a zalman fanmate to allow continuous adjustment.
https://www.amazon.com/Zalman-Fan-Speed-Controller-FANMATE-2/dp/B000292DO0

I might first contact the ups customer support with the noisy fan issue.
Normally a UPS fan should not be audible.
There may be a clogged filter or other reason why the fan should run at high rpm.

If all else fails, can you move the ups more distant from your hearing?
 
It looks like a proprietary connector.
Without a third fan speed connector, the fan will run at max speed all the time.
You could try to construct a voltage lowering cable mod to run the fan at a lower 7v. or 5v.
https://www.techpowerup.com/articles/other/137

Or, better yet, modify a zalman fanmate to allow continuous adjustment.
https://www.amazon.com/Zalman-Fan-Speed-Controller-FANMATE-2/dp/B000292DO0

I might first contact the ups customer support with the noisy fan issue.
Normally a UPS fan should not be audible.
There may be a clogged filter or other reason why the fan should run at high rpm.

If all else fails, can you move the ups more distant from your hearing?
I have cleaned the fan and it is still noisy, the fan only turns on when the batteries are in use or when it detects a low voltage, in spite of this and as far as I know the fan is set to turn on at 100%.

I checked the header and I can remove the small white plastic, so I think there will be no problem to place any fan.
 
You need a 3-pin fan, not 4-pin. This WILL require some custom wiring, but not much.

Since you have the old fan working still, get a voltmeter. With the UPS on and working (CAREFUL inside!), check that the RED wire of the fan gets the + voltage (probably 12 VDC), and Black is Ground (the - part of power supply). That is the likely use of the colours.

I assume you do NOT want to save the old fan, so you can cut off of it the wires with the 2-hole connector on the end. Now, on the new 3-pin fan, the colour colded wires always are : Black - Ground, Red = + VDC, and Yellow = Speed signal. So cut off that connector and splice onto it the old fan's wires: Red to Red, Black to Black. Tape the end of the Yellow wire and just coil it up out of the way - do not connect it to anything.

This will get the replacement unit to work just like the old one. IF the UPS system does its own fan speed control, it still will. IF there is NO speed control BUT you decide you want to reduce the Noctua's speed, there is a way using some speed reducer modules that come with the fan and a DIFFERENT custom cable modification. So if you want that, post back here BEFORE all the cutting and splicing!
 
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Necesitas un ventilador de 3 pines, no de 4 pines. Esto requerirá un cableado personalizado, pero no mucho.

Ya que todavía tiene el viejo ventilador funcionando, obtenga un voltímetro. Con el UPS encendido y funcionando (¡CUIDADO por dentro!), verifique que el cable ROJO del ventilador reciba el voltaje + (probablemente 12 V CC) y que el negro sea tierra (la parte - de la fuente de alimentación). Ese es el uso probable de los colores.

Supongo que NO desea guardar el ventilador viejo, por lo que puede cortar los cables con el conector de 2 orificios en el extremo. Ahora, en el nuevo ventilador de 3 pines, los cables fríos de color siempre son: Negro - Tierra, Rojo = + VDC y Amarillo = Señal de velocidad. Así que corta ese conector y empalma los cables del viejo ventilador: rojo con rojo, negro con negro. Pegue con cinta adhesiva el extremo del cable amarillo y simplemente enróllelo para que no estorbe; no lo conecte a nada.

Esto hará que la unidad de reemplazo funcione igual que la anterior. SI el sistema UPS realiza su propio control de velocidad del ventilador, igual lo hará. SI NO hay control de velocidad PERO decides que quieres reducir la velocidad de Noctua, hay una manera de usar algunos módulos reductores de velocidad que vienen con el ventilador y una modificación de cable personalizada DIFERENTE. Entonces, si quieres eso, ¡publica de nuevo aquí ANTES de todo el corte y empalme!
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Me gustaria saber cual es el metodo de los accesorios de Noctua que mencionas para disminuir el ruido.
 
I said in my post that, if you want to use the Noctua units to slow the fan down, post back here for details. Your post above is just a translation of my post into Spanish I believe. Does that mean you DO want more info, or was that for a different reason?