geekhack

geekhack Community => Keyboards => Topic started by: cmr on Sat, 07 May 2016, 02:50:06

Title: Caps lock LED (on MX keyswitch) failed
Post by: cmr on Sat, 07 May 2016, 02:50:06
I have an older 87-key Leopold, and the LED on the caps lock key no longer lights up. The switch itself still works fine, but the LED never comes on, either when I enable caps lock or when I initially plug the keyboard into the USB port. The scroll lock LED is still working fine in both of those cases.

It's a brown Cherry switch with an LED embedded in the keyswitch housing, so is it fair to assume that I'll most likely have to desolder and replace the whole switch to fix it?

It's from one of the earliest batches of Leopolds sold by Elitekeyboards, so it's long out of warranty. (And even if it weren't, I punched through the warranty seal when I opened it up earlier.) Both of the solder joints connecting the LED to the PCB look good and I can't see any obvious signs that the LED itself has failed. I haven't found my multimeter yet so I haven't been able to test the LED.

I'd like to get the LED working again, but I am not particularly good at soldering and I can live without it.
Title: Re: Caps lock LED (on MX keyswitch) failed
Post by: jcoffin1981 on Sat, 07 May 2016, 03:35:45
The caps lock key is infrequently used, so you could really live without it.  If it bothers you that much it would cost you probably 30$ in materials.  Me personally, the one led not working would bother me like hell, so I would go out of my way to fix it.  That and I like a good project.
Title: Re: Caps lock LED (on MX keyswitch) failed
Post by: appleonama on Sat, 07 May 2016, 03:53:56
I'd like to get the LED working again, but I am not particularly good at soldering and I can live without it.

so what is the issue? Led's fail and the only way to fix it is to replace the led. Meaning you need to desolder and solder a new led.
Title: Re: Caps lock LED (on MX keyswitch) failed
Post by: cmr on Sat, 07 May 2016, 03:57:33
I am asking because I would like to know if there are other known failure modes for Cherry switches with integrated LEDs, or if there is a known issue with older 87-key Leopolds, other than the LED itself burning out.
Title: Re: Caps lock LED (on MX keyswitch) failed
Post by: 00zeRO on Wed, 11 May 2016, 07:26:11
I am asking because I would like to know if there are other known failure modes for Cherry switches with integrated LEDs, or if there is a known issue with older 87-key Leopolds, other than the LED itself burning out.

LED's are only integrated by pushing them through holes that pass through a switch's housing into the PCB. Just desolder the old LED and solder in a new one. Then your keyboard should be right as rain
Title: Re: Caps lock LED (on MX keyswitch) failed
Post by: jcoffin1981 on Fri, 13 May 2016, 17:01:19
It's just the luck of the draw really.  Like light bulbs LED's fail, but hopefully not for years.  Also, if your board has the ability to flip a dip switch and replace the caps lock key with say an Fn key, the light may not go on at all and this would be normal. 
Title: Re: Caps lock LED (on MX keyswitch) failed
Post by: cmr on Sat, 14 May 2016, 17:14:11
LED's are only integrated by pushing them through holes that pass through a switch's housing into the PCB.

Thanks for this tip. It had looked to me like the LED was an integral part of the switch, which it sounds like would be much more difficult to remove. Strangely, none of the literature I could find on MX keyswitches explained this!

I picked up a 25-pack of 10 mA, 3 mm red LEDs at Fry's, wicked off the solder from the old ones, and the new ones went in no problem. I would actually consider it an upgrade because the color now matches my escape key and the old blue ones were excessively bright.

Thanks!

Now I just have to see if I can resist replacing the LEDs on my Filco, which is working fine, other than the color and brightness of the LEDs now being wrong.
Title: Re: Caps lock LED (on MX keyswitch) failed
Post by: jcoffin1981 on Sun, 15 May 2016, 02:12:54
Contratulations on the DIY repair.  Desoldering is a PITA, but the final product is rewarding.