The Extron SCART Input adapters are designed to be inserted into an Extron Crosspoint input vertically, using BNC->RCA male adapters to mate with the adapter card's RCA female jacks. There are two supported BNC spacings, one that is looser (older Extrons) and one that is tighter (newer Extrons). When you assemble your card, you use the correct RCA spacing to support your Extron. The looser spacing is labeled RED1/GREEN/BLUE1/SYNC1, while the tighter spacing is labeled RED2/GREEN/BLUE2/SYNC2. You'll notice that GREEN is shared between the two spacings.
Below, you will notice that there is a design for a 'top' card and a 'bottom' card. This was required in order to get the cards close enough together horizontally (from the perspective of the Extron). The SCART heads are large and for the newer Extron spacing, the BNC spacing is just too tight to have the SCART heads stack. Therefore, you should plan to make both 'top' and 'bottom' cards, and alternate them. I use plastic standoffs to group 3-4 boards together. For the newer Extrons, I found that alternating 15mm and 16mm standoffs gave a perfect fit. Anothe alternative would be to just pair up a top and bottom board, and use either 15mm or 16mm. The error builds when you try to create a larger matrix, so you shouldn't have any problem if you make smaller matrices.
The Extron input cards have optional sync strippers that are togglable via a switch that is labeled on the PCB. The lm1881 sync stripper is powered by the SCART cable's pin 8 (switch pin). The SCART standard says that this should be carrying 5v-12v. Anywhere in that range works fine to power the lm1881.
Also, there is a small custom circuit to determine if the console is powered on, via the switch pin on the SCART connector. This can be paired with the autoswitcher to automatically switch the extron input to match the last powered-on device. This circuit takes 5-12V and lowers it down to 2.5-3.3V, which is low enough to be a simple digital 'on' signal to the autoswitcher board.
LCSC Sub-total: $14.94 for everything for 10x boards (plus lots of spare parts)
Console5 Sub-total: $14.90 for RA Female SCART connectors
TI Sub-total: $28.40 for LM1881n
BOM Total for 10x boards: $58.40 plus Console5/TI shipping
BOM Total with shipping: ~$70
You'll want 5x of the top boards and 5x of the bottom boards PCBs: $4 for 5 top, $4 for 5 bottom, plus $6 for slower shipping = $14
Cost for 10 boards, all parts: $70+14 = $84 = $8.40 each
I've respun db_electronics' Phoenix RCA plug board to use JST headers: https://github.com/rattboi/phoenix-audio-adapter-kicad/tree/jst-xh/
$5 for 10x more boards on JLCPCB order, and $0.89 for JST headers
$5.89 for 10x populated boards = $0.59 each
https://www.amazon.com/gp/product/B07HRMWVK9/
$8 for 10(need to find a better source)
https://www.amazon.com/gp/product/B005C2KA88/
$5.39 for 10
$21.56 for 40 (4x per board, 10 boards)
Alternative:
https://www.amazon.com/gp/product/B01H1A4QAQ/
$6.42 for 10
$25.68 for 40
10x board + phoenix + cables + adapters: $84 + $6 + $8 + $22 = ~$120
$12 each, all parts, shipped
If you were to remove the optional components (no sync stripper, no sense circuit), you can get the price down further
Removing switch + lm1881 and passives for lm1881 + passives for sense circuit + sense connector:
LCSC Sub-total: $7.06
Console5 Sub-total: $14.90 for SCART connectors
BOM Total with shipping: $7.06 + $14.90 + $5 = $27
PCBS are the same, so $14 for 10x boards shipped
The rest of the parts are the same
10x board + phoenix + cables + adapters: $41 + $3 + $8 + $23 = ~$75
$7.50 each, stripped-down, shipped