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geekhack Community => Keyboards => Topic started by: TeacherGeek on Wed, 05 June 2019, 00:18:49

Title: LEDs not working on PCB
Post by: TeacherGeek on Wed, 05 June 2019, 00:18:49

So I got some LEDS and all of them worked on my PCB except this purple one. The legs were particularly longer too.

I was wondering why this might be? The head seemed to be the same size as the other colours.

Title: Re: LEDs not working on PCB
Post by: Findecanor on Wed, 05 June 2019, 09:21:28

Did you install it the right way around?

Title: Re: LEDs not working on PCB
Post by: TeacherGeek on Wed, 05 June 2019, 23:28:04

Yeah, I tried both ways. The LEDs worked on another PCB but not the one I wanted them on.

Same store, different colours but one colour didn't work.

Title: Re: LEDs not working on PCB
Post by: Sup on Thu, 06 June 2019, 04:02:19

What PCB? can you show the soldering. Could be that it may miss a component. I had this once with a GH60.

Title: Re: LEDs not working on PCB
Post by: TeacherGeek on Thu, 06 June 2019, 14:20:37

i put in another LED and it works on the same slot.

The non working LED works on another PCB.

This is what makes it  weird for me. Do LEDs need a certain voltage and the first PCB doesn't have it?

Title: Re: LEDs not working on PCB
Post by: Findecanor on Thu, 06 June 2019, 14:36:30

A LED (every diode actually) has a minimum voltage. Check the "forward voltage" in the data sheets for your LED's and compare.

I believe LEDs selected for a keyboard should be very power-efficient types: very bright with low current draw. A properly designed keyboard PCB should always dim the LED to a fraction of its full brightness by using PWM, not by reducing the voltage.