Recently, we redid the wiring on our club's large O gauge layout. Before, it was a combination of star wiring on the three circular loops, and a bus wire on an extension that branches off from the outer loop and wraps around the room. One of our members is an electrical engineering student, and he redid the wiring into an all-bus wire configuration (using suitcase connectors). Before the rewiring, we were able to operate all our PS2 and PS3 engines, with occasional weak signals, but all the engines were read from the DCS remote and from our phones (we run DCS 6.00 on a REV L TIU with the WIU and a TMCC base connected). After the rewiring, engines could only be picked up by any device (including the remote) sporadically at best. As in, whenever the READ key was pressed, not all the engines on the track would be picked up. I became convinced that the issue lay in the bus wiring, and today, I rewired the outermost loop of the layout (which has three power drops) into a star-wired pattern (an individual feed to each drop), while leaving the inner loops unchanged (in bus) and the extension electrically isolated. However, when I went to test the setup, only our PS3 GP20 (30-20092-1) was picked up on anyone's device. The other two engines on the track, a K4 (30-1478-1) and a SW1500 (30-2749-1, hardly a year out of an overhaul by MTH) were not picked up; they remained silent, until there was a deliberately caused short (in trying to connect the circuits for the inner and outer loops) at which point both engines fired up, unbidden, but were still unresponsive. Most odd of all, however, was that whether the GP20 was running on the star-wired outer loop, or the bus-wired inner loop, when asked to do a signal test, the engine read the signal as a 10.
I'm at a loss as to why we can't pick up the K4 and SW1500. The electrical engineering student thinks it could be that the batteries (neither has been replaced with a BCR, as far as I know, since both engines were donated) are flat, which is possible, since we don't run the trains every week, but I think there's something else as well.
Any ideas?
Could it be low batteries in combination with a weak DCS signal?
