Tour Easy Rear Running Light: LED Lens Assembly

Having discovered the need for careful alignment of the LED PCB with the lens, I paid more attention to detail this time around.

The LEDs arrive soldered to PCBs atop aluminum star heat spreaders, but the one I picked out of the bag looked slightly misaligned. Unsoldering it showed a smear of solder paste had melted across the central pad:

1 W LED PCB - errant solder
1 W LED PCB – errant solder

The LED has a die contact slug on the bottom which, I suppose, could be directly soldered to the spreader. For my simple needs, removing the errant solder, plunking the LED atop a layer of heatsink compound, and resoldering the leads should suffice:

1 W LED PCB - wire layout
1 W LED PCB – wire layout

The LED holder has a pair of slots aligning it with the LED leads on the PCB. The base of the holder sits flush against the PCB, so the wires must attach directly to the LED pads.

I ran the wires for the amber light through holes close to the pads:

1 W LED Running Light - heatsink fit
1 W LED Running Light – heatsink fit

Which required chewing two passages in the base of the holder:

1 W LED Running Light - wiring
1 W LED Running Light – wiring

It turns out the 5° and 10° lenses are strongly conical and leave plenty of room around the LED to run a wire around the inside of the holder, so I drilled a pair of holes to put both wires on the same side of the circuit plate:

Tour Easy Rear Running Light - circuit plate attachment
Tour Easy Rear Running Light – circuit plate attachment

The holder required minor surgery to let the wire double back on itself over the LED pad:

1 W LED Holder - wire passage
1 W LED Holder – wire passage

The wires thread through two holes drilled in the plastic holder:

Tour Easy Rear Running Light - clamped LED assembly
Tour Easy Rear Running Light – clamped LED assembly

More urethane adhesive glues the PCB to the LED holder, with the clamp applying pressure to the lens to ensure the lens seats properly around the LED. It turned out that worked well and the light has a nicely rounded beam.

With the optics bonded together, metal-filled JB Weld epoxy attaches the heat spreader to the heatsink with good thermal conductivity:

Tour Easy Rear Running Light - clamped LED heatsink
Tour Easy Rear Running Light – clamped LED heatsink

The LED holder is a slide fit in the heatsink, so the clamps can keep the PCB flat on the bottom of the recess while the epoxy gets a good grip on all parts.

Now it’s just a matter of wiring everything up!

Spam comments get trashed, so don't bother. Comment moderation may cause a delay.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s