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geekhack Community => Keyboards => Topic started by: CaffeinePizza on Mon, 22 June 2015, 18:35:45

Title: Numlock LED issue? 1989 Model M 1391401
Post by: CaffeinePizza on Mon, 22 June 2015, 18:35:45: So often, my LED light for Numlock will turn off and on, maybe flicker like a bad light bulb. The numpad still works, so numlock doesn't actually turn off. The caps lock and scroll lock LEDs do not do this. I cleaned the contacts of the membrane cable from the main board to the LED board with a smooth pencil eraser to remove corrosion. Nothing is fixing this. I do have another Model M from 1991/1992 that I may can get a replacement LED board if needed. I'm not sure what's going on. I've tried googling this issue but to no avail. I'm also using an active PS/2 to USB converter (blue box thing). I haven't tried on a computer with a motherboard PS/2 port. This keyboard is freshly bolt modded by me. Thanks
Title: Re: Numlock LED issue? 1989 Model M 1391401
Post by: Snowdog993 on Tue, 23 June 2015, 01:04:57: Quote from: CaffeinePizza on Mon, 22 June 2015, 18:35:45
So often, my LED light for Numlock will turn off and on, maybe flicker like a bad light bulb. The numpad still works, so numlock doesn't actually turn off. The caps lock and scroll lock LEDs do not do this. I cleaned the contacts of the membrane cable from the main board to the LED board with a smooth pencil eraser to remove corrosion. Nothing is fixing this. I do have another Model M from 1991/1992 that I may can get a replacement LED board if needed. I'm not sure what's going on. I've tried googling this issue but to no avail. I'm also using an active PS/2 to USB converter (blue box thing). I haven't tried on a computer with a motherboard PS/2 port. This keyboard is freshly bolt modded by me. Thanks

This issue could be 1 or 2 things. #1 is most likely.
#1.
Ribbon cable cleaned on LED side but not controller side. Be sure you cleaned pins 9-12 on the controller and cleaned the ribbon cable on that end as well. That may fix it right away. If not, you might need to use an Arduino cable and use that instead. I used F-F with 4-pin molex connectors. But you can improvise.
Pictures speak louder than words.
More
(http://i.imgur.com/gPGobRK.jpg)
(http://i.imgur.com/Bdt5db9.jpg)
(http://i.imgur.com/ITkL6Hp.jpg)

#2.
Bad LED itself. Unlikely. You say it does flash, so I seriously doubt that. Of course it could be a transistor or something on the controller itself.
Title: Re: Numlock LED issue? 1989 Model M 1391401
Post by: fanpeople on Tue, 23 June 2015, 02:06:53: Did you clean the membrane before or after the problem started, I would try reseating the membrane/cable doobie. Push it in harder and jiggle etc. Also could use jumpers from the controller to one of the other LEDs to see if you get the same problem with a different LED.
Title: Re: Numlock LED issue? 1989 Model M 1391401
Post by: CaffeinePizza on Mon, 06 July 2015, 11:20:03: I thought I would add this, but the site was down of course. Now I'm around to it!
I do have a spare Model M that can donate me some parts if it's needed.
Title: Re: Numlock LED issue? 1989 Model M 1391401
Post by: Snowdog993 on Mon, 06 July 2015, 12:32:18: Try a different USB port. Preferably one on the motherboard itself. It could be that the drain from the keyboard is more than the port itself is capable of. They are usually in pairs, so try to connect the keyboard to a port that is not using the other.
Hopefully this will resolve the problem. Like I said in my previous post, be sure that the ribbon cable and connections to the ribbon cable are good. If you didn't look at my pictures before, maybe you should look.
I just use a 4-pin arduino cable with a 4-pin M/M connector on both sides. If that ribbon is bad, it will do this no matter what you try. As long as the numlock functions properly, this tells me that there is a controller-LED panel connection issue.