LED Backlit Keyboards

Deck 82 Optional Perimiter LED Installation Instructions

NOTE: Some of this information is outdated, I am working to make it nicer. DeckGuy Adam 06-25-09

On keyboards with translucent plastic enclosures, up to 6 LEDs may be installed at fixed locations around the perimeter of the keyboard's printed circuit board. However, doing so will require a soldering iron, solder and wire cutters. A digital multi-meter (DMM) or continuity test isn't necessary but could be helpful if you already own them. If you make a mistake, you will also need a solder removal tool and needle nose pliers. Finally, you must also buy your own LEDs.

Which LEDs do we use or recommend and where can I buy them? Unfortunately the ones we use aren't available to individual consumers. Do we sell the LEDs to our customers? No, because we would have to charge you $10 just to cover our costs. Why don't we just include them with the keyboard? Then we would have to charge those customers who don't want the perimeter LEDs the cost of these LEDs. Therefore we will leave selling electronic components to the experts who can do it efficiently; the buying of the peripheral LEDs to those who want them, and we will stick to manufacturing keyboards.

Here are the characteristics of the T1 or 3mm package LEDs we use:

• Red: Forward voltage = 1.8V at forward current of 20mA; 500mc luminous intensity; 30 degree viewing angle.
• Yellow: Forward voltage = 2.3V at forward current of 20mA; 2000mc luminous intensity; 30 degree viewing angle.
• Blue: Forward voltage = 3.4V at forward current of 20mA; 2600mc luminous intensity; 30 degree viewing angle.
• Green: Forward voltage = 3.2V at forward current of 20mA; 3800mc luminous intensity; 40 degree viewing angle.
• White: Forward voltage = 3.3V at forward current of 20mA; 4000mc luminous intensity; 30 degree viewing angle.

Please note that TG3 drives these LEDs at around 5.25mA maximum, but LEDs are commonly specified at 20mA. Also note that the Toxic (green) and Frost (white) boards are based on the Ice (blue) product.

As you can now see, the current and voltage characteristics of LEDs vary with color. They also even vary between manufacturers and part number for LEDs that are the same color. Therefore your perimeter LEDs may not "track" the factory installed backlighting LEDs with regard to turn-on thresholds and luminance intensity at any given brightness level. You can still use LEDs with slightly different current and voltage ratings, and lower luminous intensity - they will still work but may not be as bright or "track" as well.

We recommend that these perimeter LEDs be installed on the bottom-side of the printed circuit board (PCB). Installing them on the topside will result in very bright "hot spot" points of LED light because the housing plastic allows more light to pass through then the keycaps. The location of these 6 LEDs is shown in Figure 1. Be careful of clearance between the bottom pan and the bottom of the printed circuit board - especially for LEDs DS28 and DS29. The LED package should be either T1 or 3mm to match the lead spacing of the PCB. LEDs are also "polar devices". This means that they can be installed in the wrong way that will cause them not to work. LEDs have "anodes" (positive terminal) and "cathodes" (negative terminal). The cathode should be installed in the square shaped solder pad on the PCB; the anode should be installed in the circular pad. Failure to install the LEDs with the proper polarity is the most common cause of the LEDs not lighting.

The perimeter red and yellow LEDs must be installed in pairs as shown in Table 1 and Figure 2 per the factory installed resistors. Referring to the schematics shown in Figure 2, the red and yellow LEDs are installed with two of them "in-series" in order to reduce the overall current consumption of the keyboard. The blue LEDs are installed "in-parallel" because the sum of the forward voltage drops is 6.4V - that exceeds the +5V power supply, so the blue LEDs would not turn-on if wired with two of them "in-series". TG3 has already factory installed the resistors shown below in Table 1. These values are for "typical" LEDs of their corresponding color.

Can a different color perimeter LEDs be installed (for example, yellow perimeter LEDs on a red backlit keyboard)? Yes, again we recommend followings the guidelines in Table 1 and Figure 2. 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.

Can a mixture of colors be used for the perimeter LEDs? Yes, but again we recommend followings the guidelines in Table 1 and Figure 2. We further recommend that you adhere to the rules regarding keeping the red and yellow LEDs in pairs (i.e. DS24 & DS26, DS28 & DS29, DS25 & DS27). This also insures that the LEDs will "track" each other with regard to turn-on thresholds and luminance intensity at any given brightness level.



Reference designators are simply text printed on the printed circuit board next to electronic components in order to identify them. The conventional reference designators for LEDs are "DS" followed by a unique number (i.e. DS24 or DS26); resistor reference designators are "R" followed by a unique number (i.e. R100, R100B or R100G).

CAUTION: Since TG3 is not supplying perimeter LEDs with the keyboard, it is up to the modifier to select and install the proper current limiting resistor value, tolerance and power rating to meet the LED manufacture's specifications. Choosing improper resistor values could cause USB to detect an over current condition and disable the keyboard's port. Worse cases scenarios could result in fire and permanent damage to the keyboard.

See our warranty and product disclaimer here.