2465B cable I can't identify, what is it for?

Grayson Evans

I am reassembling my 2465B after PS overhaul. There is a two conductor "cable" that comes from the A4 readout board and looks like it is supposed to plug into J305 on the A3 inverter board (which is +5V). It seems to me when I took the PS out this was not connected to anything.
No manual I have been able to download has the A4 board that is in my scope, so I can't find what the cable is for. One of the manuals I have shows a small A4 board (about half the length of the PS). But the one in my scope is full length, the same size as the processor board.
Thanks for any help.