Razer Imperator LED swap. Need help identifying.

[skorpien]

I've recently put together a computer with mostly green and orange LEDs, and one thing that's been bothering me is that my Razer Black Widow and Imperator (which I'd purchased a few years back) had blue LEDs.

So I figured I could try to swap out the LEDs as I have had experience soldering and working with them from my recent build.

I'm running into a bit of a problem with the Imperator mouse. When I opened it up I saw there was a 5mm LED for the breathing logo, but the scroll wheel illumination is done with a small circuit board with two SMD LEDs.

I was wondering if anyone here would be able to help me identify exactly which SMD LEDs I'd need to purchase to replace them. I have tried searching online but there are quite a few that look very similar.

If all else fails, I may just wire a 3mm LED to the leads powering the SMD LED board, but I'd like to try my hand at replacing the SMD LEDs first if possible.

 

[Bobnova]

0805 package it looks like, 270 ohm current limiting resistors, so probably ~12mA.
Beyond that, there is really no way to tell.
Your options are to buy a couple 0805 LEDs in the color you want that can deal with 12mA. or to do a hackjob and solder 3mm through hole resistors in their place (which should be fine).

 

[skorpien]

Thanks Bobnova.

I've measured forward voltage and source voltage using a multimeter if that would help? The readings I got were ~2.9V and ~4.9V respectively, so probably 3V or 3.1V forward voltage and 5V source voltage I'm thinking.

I'm trying to find them through Digi-Key but the only Green SMD 0805 package LEDs come in 10mA and 20mA variants, with the 10mA available in only 2.1V. According to a circuit calculator, that'll require a 330 ohm resistor.

2.2V and 3.1V are available in 20mA, but again, according to the calculator they would only require a 150 ohm or 100 ohm resistor respectively.

Am I right in assuming that the 2.2V or 3.1V 20mA LEDs will still work with a 270 ohm resistor, but will be dimmer than if I were to use a 100 ohm resistor?

Apologies if these questions are a bit basic...

Or would it just be less headache to wire a 3mm LED to the 5V source voltage with the proper resistor?

 

[Bobnova]

Yeah just go with the 20mA LEDs, that'll be fine.
They won't be as bright as they would be with the full 20mA, but they should be plenty bright.

Most blue LEDs are ~3V voltage drop, so that sounds about right.

Odds are that pretty much any LED you solder in there will work nicely really, they aren't terribly picky. Putting more current through an LED than it is rated for will shorten it's life, so that's not ideal. Putting less than it's rated for is fine, recommended really. Pretty much anything run at its max rated power will die sooner than if it's run at a lower power.

You may want to get both 2.2v and 3.1v variants, or get the 2.2v and a few different resistor sizes, in case a straight swap results in LEDs that are too bright.