I drew up a quick plug n' play guide here; that anyone can use without needing to consult the Switch Matrix
Of course without a schematic, there would be no way to know (without having the game in front of you), that there is a Black wire with White Stripe that is the "traveler wire" that connects the Left Jack Bank with the Right Jack Bank. This traveler wire lets the game know when all the drops are down on both sides of the playfield.
So looking at the above to follow the logic:
We need the game to see all 4 targets down.
Williams calls this event "Jack Drop Target Series" Switch Closure #35
So, we see on the Switch Matrix that ROW 3 (White/Orange Stripe) needs to complete the circuit to COLUMN 5 (Green/Black Stripe)
Look how the White/Orange wire on the Diamond board, connects to the Club board (black wire), then across the playfield to the Hearts (Black wire), and finally to the Spades where it meets up with the Green/Black wire to complete the circuit.
Take a second and follow the circuit path until you "get it"
The above guide assumes you have the playfield ass-up on a rotisserie.
You can see that the Diamond drop target uses a double-diode Red board, the rest use the standard Green board.