The new board

With these ideas in mind I started over again. I measured the LBs and decided that the new board should be able to mount in the box without tilting and if it could fit straight in - all the better. It should interface with the existing LED board directly so the whole assembly could be replaced as a unit, if necessary, so it should plug in to a cable that remains with the semaphore LB. The LB measurements showed that the board had to be about 35-40% of the size of the existing board. First I lined up the resistors and divided them by input and output primarily into two groups and put the IC (integrated circuit) between them. The output transistors went up the long side of the board to drive the LEDs. Then I realized that the LED circuit board was not necessary if the LEDs mounted to the edge of the new board so I added the LED board circuitry to the Logic Control Board and voila! Now I had a design that fit the LB straight in and could be used as a module to make servicing easier. When mounted to the LB cover, it can be plugged into the semaphore connector and then the LB cover screws hold it all in place. It makes it trivial to replace a malfunctioning signal. What would take us a hour or so normally can be done in minutes now! The module can be repaired in the shop instead of the field so it speeds up repairs.