This is a close-up of the earliest T4A unit I've ever seen. This particular T4A came out of a compressor that has earned the nickname 'Majik' because of its incredible sound. Every signal run through Majik came out sounding better than it did going in. I will publish more information about Majik on this site at a later date.
The above photo clearly shows the glass-encapsulated Claired CL-505L photocells used in the earliest Teletronix LA-2As. Notice that the photocells are oriented vertically and the electroluminescent panel sits transversely on top of the photocells. No circuit board was used in the construction of the unit.
Notice the paperclip soldered around the copper strip to which the electroluminescent panel is soldered. It appears that the copper strip performed at least two functions. It provided structural rigidity and a mounting point for both the electroluminescent panel and photocells, and also provided good grounding and shielding.
This view shows the way the copper strip was grounded to the can. You can also clearly see the paperclip that is an integral part of the assembly. I have not been able to find any documentation as to the brand of paperclips used :-)