Dash Panels and Switches, Part 2

OK, let's convert a switch to LED indication. First, the switch actuator, the part that actually rocks back and forth, has to be removed from the switch body. It just snaps in place, so, to remove it, you have to gently pry up one side, and then the other side, until it releases from the body. Be gentle, it does come off. Set it aside once it is free.

The switch body itself looks like this:

Now, if you look at the body carefully, you will notice that it also comes apart. There is a retention tab on either end of the switch. Gently pry these away from the body, and carefully separate the two halves of the switch:

There is a small rocker assembly in the portion of the switch on the left - this remains unchanged. Just be sure to keep the rocker properly placed on the fulcrum. If you invert the switch, it will fall right out, so be careful. On the right, you can see what we are after. Remove the white plastic roller assembly from the upper body, and put it aside. Inside the body, you will then see the incandescent bulb:

There are two wires that are set into wire guides - pry them out with a small screwdriver or suitable tool, then remove the bulb by carefully releasing it from the retention tabs. You will then have this:

Discard the bulb. Now, you will take the LED and resistor you purchased, and carefully solder them together, as seen in this picture:

This is the replacement assembly for the switch. The LED will fit back into the body just like the incandescent bulb. Be careful to keep the O-ring in place - it seals the bulb to the body, and keeps contaminants out of the switch. Then, route the two wires in exactly the same way the incandescent bulb wires were routed. The resistor just tucks into the body out of the way, and doesn't interfere with the switch at all. You'll wind up with something like this:

A word of caution - LEDs only allow current flow in one direction, so if you install the wires in the wrong direction, the LED will not illuminate, and you'll have to reverse the wires. I recommend that you simulate the install before tucking the wires in place, so you don't waste any time. Once the install is done, simply snap the two halves of the body back together, and then snap the actuator back onto the body. Now, you have a cool running, long lasting switch with indicator! Finished, it will look like this:

Now all you have to do is repeat this 20 or 30 more times, and your boat switches will be done.

Dash Panels and Switches, Part 1

When we first purchased the 340, one of the things I noticed was that many of the switches on the dashboard didn't "indicate" properly. To clarify - many of the rocker switches on the dash have small, built in incandescent indicator lamps. When the switch is turned "on", these lights illuminate, so the operator knows that circuit has been activated. But, over time, a couple problems inevitably manifest:

1 - Since the lights are incandescent, the do eventually burn out, leaving that circuit without a status indication.
2 - Incandescent bulbs generate a substantial amount of heat, and, over time, that heat degrades the plastic of the switch body. Eventually, the switch body may start to crack around the bulb, and the little bulb starts flopping around inside the switch.

So,  what to do? My answer is to replace the  bulbs with LEDs. Light Emitting Diodes solve both problems, since they have a life that is vastly longer than incandescent bulbs, and they generate far less heat. A couple suitable LEDs are here:

http://www.unique-leds.com/index.php?target=products&product_id=1953
http://www.unique-leds.com/index.php?target=products&product_id=1883

The royal blue one (1000 mcd) isn't as bright as the deep blue (2000 mcd), but either one will work quite well. They have basically the same dimensions as the incandescent bulb being replaced, so they snap right into place, and the O-ring seal around the bulb is still effective.

Now, if you look at the specifications for these LEDs, you'll note that the forward voltage is specified as between 3.0 and 3.6 volts (we'll use 3.3 for calculations). As such, a resistor is required in the bulb circuit, to drop the voltage into this range. Assuming worst case for a boat operating at roughly 14.4 volts, we see we have to knock (14.4 volts - 3.3 volts) 11.1 volts out of the bulb circuit for proper operation. Using Ohm's law, and the example of the Royal Blue LED (30 mA forward current), we have 11.1v / 30 mA (1000mA / 1 A) = 370 ohms. So, a roughly 370 ohm resistor needs to be in the circuit with the LED. At this current level, a 1/4 or 1/2 watt resistor is sufficient, and fits in the switch case with ease. These work fine:

http://www.mouser.com/ProductDetail/Kamaya/RC1-4394JB/?qs=sGAEpiMZZMuDPtTs5Gda260u%252bQsOF0S4HuXtl3e2gOo%3d

In the next post, I'll show an actual switch conversion - stay tuned!