E3 Tail Light Inserts

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I noticed folks on the E3 forum looking for tail light circuit board replacements. These were probably cutting edge at the time of manufacturing, but the "traces" disintegrate over time. Like many E3 DIY'ers, I soldered in jumper wires as a fix. And it would work for a while. But the metal deposition material continues to erode and eventually the bulbs cannot complete the ground through the sockets. The project below is a more permanent solution that replaces the entire board with a machined aluminum insert with off the shelf sockets. They snap in place of the old boards and are concealed by the plastic back cover of the tail light assembly. I'll post the details of the build below, but cutting to the chase, the picture below shows the parts involved (and an original tail light shown in the upper right hand of the image).

The parts involved:

Sockets (sources off of ebay).
Copper Spade Terminals (digikey)
1/4" Aluminum Plate (McMaster-Carr 6061 T6)
M3 Socket Head Cap Screws (McMaster-Carr)
Extruded PPS Sheet for terminal block (Putnam Plastics)

The plates and terminal blocks are CNC machined.

 

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The first part of the project involved measuring out the old parts. Several parts were measured with a best guess made as to the orignal dimensions. The latter was necessary as the front and back are supposed to snap together via the tabs and slots, but the plastic definitely deformed over the past 50 years.

Machining the main plates:



Machining the sockets. There was less guesswork with the dimensions of the sockets.

 

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The finished sockets with the spade terminals being installed. Drawings for the terminals were available from digikey, so it made modelling the sockets much easier. I chose PPS as the material because I had some lying around and it is tough with good chemical compatibility.

 

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Assembly of the parts was pretty straight forward. The terminal connector assembly snaps into the aluminum plates by virtue of tight tolerancing of the parts. The bulb sockets are screwed in place and wires trimed to length to fit in to the wire channels.

 

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The positive leads are soldered to the appropriate pins of the terminal block. Note, there is an unused socket position on the original parts. I think it may have been intended as rear fog lamps. In these assemblies I wired this extra socket as an addition brake light. You can see this in the first image below on both assemblies (rightmost leads running vertically in line). Finally, the wires and terminal block were potted in place with Hysol epoxy.