AF140 LED voltage ?

Randall8686 · 26 Oct 2015 at 19:25

Hi all random question i know but does any one know the voltage of the LED's on a AF140 ? i know the fans are 12v but are the LEDs? i need to change the leds in them for the Mrs to pink. Im guessing either 12v straight off the power in or maybe a resistor and 5v led ?

Greybeard · 27 Oct 2015 at 05:42

I have to say, that's a good question. Let me find out and get back to you.

Tealc · 27 Oct 2015 at 07:09

Depends on the colour.

The forward voltage of Red is 1.8-2.0v. Blue or White 3.0 to 3.2v.

Pink is similar to blue or White.

You'll probably find a 470ohm (or thereabouts) resistor in series with each led.

If you look at the PCB where the fan wires go out to the edge you'll probably see a surface mount resistor, see what value it is.

Randall8686 · 27 Oct 2015 at 15:19

Cheers guys, i cannot see without taking it apart, However they could well be 4X 3v LED's in series on the 12v ? as there is 4 LED's

Tealc · 27 Oct 2015 at 18:48

They won't be in series with each other. The forward voltage combination of 4 LEDs would be too much for 12v, especially with blue or white LEDs.

You should be able to measure the resistance in use by measuring from cathode of one LED to the anode of the next. If the resistor is in package this won't be conclusive.

If the resistor is on the PCB and the existing LEDs are blue or White you should have no issues using Pink LEDs as a straight swap. If the existing are red I would consider adding a lowish value resistor to one leg.