First was ILS tuning panel. This panel is used to tune the ILS frequency and course sending the data via ARINC bus to the flight control computer.
It features 3 separate connectors. Each of them has the exactly same features so it gets 3 separate power feeds from different buses, and outs 3 separate data channels to L, C and R flight control computers.
Here is a pinout of the central channel connector:
As you see there is an ARINC bus channel, 115VAC 400Hz power feed, 5VAC for backlight, a park discrete that is sent when the freq is set to PARK (---.--) and a freq/test inhibit which is normally 28V feeded but it's grounded when the FCC )Flight control computer) commands it not to be able to change the freq, like during an autoland to avoid erroneous human intervention.
Here is a pic and video of the unit.