Replacing LEDS - TG3/Deck Keyboard

[Tarzan]

I was wondering how difficult it would be to replace all the LEDs on a small TG3 BL82 (Deck 82)?  I'm not a fan of red LEDs, and the small form factor looks like it would make for a good test-case for a project.

I don't have a lot of experience in electronics soldering, but I'm comfortable learning new skills.  I have soldered before, but just on household wiring, copper pipes, automotive battery cables and body-work.

Does a LED swap involve switch removal/replacement, or can LEDs be replaced in situ?

 

[dante]

http://www.deckkeyboards.com/light.php

[Tarzan]

http://www.deckkeyboards.com/light.php

I appreciate the link, thanks!

[Tranquilite]

The biggest problem with replacing the LEDS is finding similar spec LEDS in the color you want. The only other LEDs that I have been able to find in that voltage range are either orange or amber (or maybe yellow). You most likely wont be able to find any green/blue/white LEDs in the ~1.8V range.

As for actually removing the LEDs themselves, I find that it is a bit tricky to remove all the solder using solder wick/solder sucker due to the double sided PCB. However, since the leads are so close together I found that using a pair of tweezers while heating both leads with the soldering iron makes it a snap to remove an LED. After you remove the LED it is fairly easy to use a solder sucker to clear the holes.

You do not need to remove the switches to replace the LEDs (though you do need to remove the LEDs to remove the switches).

[Tarzan]

The biggest problem with replacing the LEDS is finding similar spec LEDS in the color you want. The only other LEDs that I have been able to find in that voltage range are either orange or amber (or maybe yellow). You most likely wont be able to find any green/blue/white LEDs in the ~1.8V range.

As for actually removing the LEDs themselves, I find that it is a bit tricky to remove all the solder using solder wick/solder sucker due to the double sided PCB. However, since the leads are so close together I found that using a pair of tweezers while heating both leads with the soldering iron makes it a snap to remove an LED. After you remove the LED it is fairly easy to use a solder sucker to clear the holes.

You do not need to remove the switches to replace the LEDs (though you do need to remove the LEDs to remove the switches).

The article on the Deck Keyboards site does refer to swapping resistors as well as LEDs, although they don't provide a lot of detail.

"Depending on the color of the keyboard backlighting and the color of your chosen perimeter LEDs, resistors may also need to be removed and changed with ones of different value. In other situations, resistors may be removed and not replaced (for example, adding blue perimeter LEDs to a red or yellow backlit keyboard). All resistors should be 1/8 Watt or greater and have a tolerance of 5% or better."

Any idea if the resistor reference is only for the perimeter LEDs, or are there resistors on each switch as well?  So if I can't find a LED to match the existing provided voltage, I could swap LED+resistor to get the desired LED color?

Apologies for all the questions, I've only had one back-lit board previously (CM Trigger), and I haven't taken it apart in any way.

[WhiteFireDragon]

The proper resistor must be matched with the corresponding LED based on voltage and current, otherwise you'll have dim LEDs, or the opposite where it's too bright or just burn out. But for keyboards, generally you'll be within tolerance even if you don't change out the resistor if you just use standard 3mm or T1 size LEDs. Try a few first and see if the brightness is ok, then solder on the rest.

I think you mean each switch has individual diodes, not resistors. LEDs have individual resistors.

[Tarzan]

The proper resistor must be matched with the corresponding LED based on voltage and current, otherwise you'll have dim LEDs, or the opposite where it's too bright or just burn out. But for keyboards, generally you'll be within tolerance even if you don't change out the resistor if you just use standard 3mm or T1 size LEDs. Try a few first and see if the brightness is ok, then solder on the rest.

I think you mean each switch has individual diodes, not resistors. LEDs have individual resistors.

Thanks!

Time to get a better soldering iron...   

[Tranquilite]

One more thing to note. The BL82 with red LEDs is wired in such a way that all the LEDs come in pairs of two wired in series which gives you at most 2.5V per LED with the current circuit setup, which is still not quite enough to get the more fun colored LEDs rated at ~3.3V to light up (trust me, I've tried). However, I do admit that I haven't tried replacing the resistor(s) associated with the LED circuit (in fact I haven't even been able to find the resistor(s) associated with the LED circuit), so I suppose there might still be some way to get the color you want, but I'm not particularly optimistic...

I think you mean each switch has individual diodes, not resistors. LEDs have individual resistors.

LEDs don't have to have individual resistors. The two reasons for resistors in the first place is to get  the LED working at the right voltage, and to limit current draw to prevent thermal runaway. You can usually get away with using a single resistor to limit the current of multiple LEDs.

I really wish the red LED BL82 boards were easier to LED mod. I would have changed the LED color in mine a long time ago if that was the case.