I am hoping someone can share some knowledge.
I recently obtained an unpopulated Gottlieb display board from The Pinball Resource (PBR). It is listed on PBR as a Gottlieb System 80B board. When I Compare it to the board in my System 80B pin it appears the same with the exception of a capacitor added at C7 (see attached photo).
I followed the circuit from it where it enters at A4J1 to it’s end at the display glass . The circuit, as far as I can tell, is the same as the circuit from in the Gottlieb manual (Chicago Cubs Triple Play, CCTP). There in one exception that I see. That is a capacitor added between the incoming input from A4J1/#10) and Z2/pin 9.
I highlighted the circuit on the board from PBR (see attached picture). The outgoing path on the PBR board from Z2/pin 8 to U2/pin 5 is the same as the the schematics for board CCTP A4 board.
Since the CCTP schematics does not include C7, I am unsure of what capacitor could be used. If the board is populated with components per the CCTP manual, can C7 be left unpopulated? If not, can someone suggest a suitable capacitor?