Thanks Jeff! I'll try to follow up with schematics and whatnot. Glad someone's interested.
Here's the circuit layout of rev B of the board. I included as much info as I could about the components on the silk screen mask so it could give someone a hint of what's going on sans schematics.
![[Linked Image from seriss.com]](https://seriss.com/people/erco/tmp/1a2-board-REV-B--film-rental-mods--FINAL--screenshot-redgrn-labels.png)
This is revision B of the board.. one thing that's wrong is the direction of the diodes for the "BELL CALL" section on the silk mask. When I got the boards back from the printer and soldered it up, phones wouldn't ring unless I desoldered the diodes and flipped them all around. Will fix that in rev C. Was surprised it mattered, I thought the bells would ring on either side of the AC cycle.. didn't catch that in R&D.