The second PCB, 'Reformatter PCB', looks like it dealt with producing the NTSC video image and has power supplies (MIC4680, LTC3401)
There is a 24MHz clock, TI TMS320VC5410 DSP, and AD9708 8 bit DAC.
It has the end user connections of J1 and J3.
1 Power in + 6 - 32V. DO NOT EXCEED 33V
2 0V Ground
3 Low Battery Shows a low battery logo when grounded. Software version dependant.
4 RS485+
5 RS485-
6 Ground Ground
7 Shutter Ground to force a manual shutter / flat field correction
8 Video Polarity Ground to select black hot imagery
9 Low Voltage in 2.5V - 4V an alternative to using pin 1, typically 2 x AA cells. DO NOT EXCEED 5V
10 Power Out Connected to pin 1 via a diode to aid wiring.
11 3.4 - 3.7V out To drive a display, 250mA maximum
12 Video Gnd Ground
13 Video NTSC video
This is all public domain as the user guide is available on the internet, and not marked commercially confidential.