Stepped on the USB cable again ripping the USB plug off the MAGA board again. New design: Short USB A-to-B cable with strain relief and a USB extension cable to the PC.

With some repair got all 36 sensors and the relays connected, with two faults: 1 - IR sensor has failed and 1 - cabling problem.

Modified a replacement IR sensor, installed. All is well. Cabling issue is still outstanding.

Troubleshooting one problem I discovered that things work when the track is up but not when its down! Developing a troubleshooting plan. So do not want to unplug the sensors expecting that will introduce new failures. But the locos will not stay on the track when it is tipped up.

Fixed the cabling problem for IR #6. Still no real answer for the up/down problem. What a rat's nest! 37 3-wire cables plug in there. Arduino/Motor Shield, IR sensor wiring detail

Short week; many distractions.