[Help] LED lighting underneath PCB for Acrylic case

[daviswalkers]

So I recently added LED's to my Poker II I screwed up one soldering pad so I put led's in every other  switch to avoid one blank spot.


I also just bought an acrylic case from massdrop with the intent of trying to find a way to light the case as well, I was originally looking into LED strips but just thought of something and was unsure if it would cause any harm or if it would even work.

What I was thinking is in the extra switches that don't currently have any LEDs in them I could put the LED's in backwards (so the LED would be on the bottom of the PCB not the top of the switch) to give it a glow through the case.  Would this be an issue? I'm completely incompetent when it comes to electronics and PCB's more specifically so I see no issue but there could be more than meets the eye.

[suicidal_orange]

It makes no difference to the circuit which way up you put the LEDs as long as you get the legs right.  It would probably be easier to bend them over so you can reach the pad to solder to, and you'll need to make sure they fit between the PCB and the case but other than that there are no issues. 

Looking forward to seeing pics

[daviswalkers]

It makes no difference to the circuit which way up you put the LEDs as long as you get the legs right.  It would probably be easier to bend them over so you can reach the pad to solder to, and you'll need to make sure they fit between the PCB and the case but other than that there are no issues. 

Looking forward to seeing pics

Awesome! Thanks, I think I'll lay the LED's flat, since I have the rectangular leds and not round they shouldn't be an issue with fitting underneath. Sadly it's going to be awhile since the case is from massdrop but I'll definitely put an update post in here once I have it!

[daviswalkers]

So I soldered them in and everything worked, a little less light than I had hoped but I don't have the acrylic case yet so I'm not too worried. Tested every key and everything worked. Until I brought it back to work, randomly my 6 key stopped working, however if I press it harder than normal it zoom's in firefox, as if I was doing "CTRL + +" or something only it's like I did it 15 times, also it smells like what it smelt like while I was soldering it ever now and again, I'm thinking the leds wires are touching the aluminum case and somehow shorting out or something as I had to basically bend the led to be closer to the edge of the pcb. I'm hoping this wont be a problem once I put it in the acrylic case but if it is I guess I'll just have to take out one more led

Edit, slightly moved some of the leds around and adjusted the wires so they weren't laying flat on the PCB and all the keys work again, sadly all I can smell is that solder smell now, so hopefully it will dissipate and I can see if it's a continuous issue or if I fixed that as well.

[suicidal_orange]

You could put some tape on the case where the LEDs touch, that would prevent shorting.  Didn't mention that as your case was supposed to be acrylic...  And yes, adding powered LEDs to a key matrix will do funny things so keep the LED leads away from everything else (switches and diodes) too!

There isn't enough voltage in a keyboard to cause any burning unless you've got an LED wired in without a resistor, in which case you will kill the LED but nothing worse.  It should be leftover soldering smell and will pass

[daviswalkers]

Electrical tape the best to use or will scotch work? Yeah I have a aluminum case for the time being until the acrylic one ships (swear I mentioned it but oh well) and yeah after I fixed it I messed up my 2 key so whenever I hit it it did "123456667567" pretty weird stuff for sure... I spent a lot of time moving this around and didn't have any other issues, but the smell seemed to persist most of the day, I think it might just be the solder getting hot but when I check it's always cold so you're probably right about residual smell, I guess tomorrow will tell

[suicidal_orange]

You did, I was just sleepy and thinking of pretty acrylic cases )  Any tape will work as an insulator, you just find some that sticks to metal and isn't thick enough to cause a problem.

What you saw is not weird at all (except the multiple 6s) - you just got a preview of how a keyboard works.  The controller constantly sends signals and then records where they come back know which key was pressed, you shorted the number row return to LED power so no matter which column it sent power to a signal came back from the number row and it registered a keypress.  No damage done

Hopefully it smells better by now!

[daviswalkers]

So it doesn't smell better, as soon as I plug it in the smell starts again, when I have lunch or a break I'll take it out of the case and see if I can find a heat source or if it still does it out of the case.