Wiring MTH AIU

Joe, all of the IN terminals on the AIU are isolated from each other. You can feed anything you wish.  In fact, as I described in another thread, you can use IN for output in a specialty circuit.  The reason for the instructions is that the wiring must be that way if you want to have switches wired for non derailing mode.

Joe,

Has anyone put power to the IN terminal of the AIU instead of the ground? 

The reason for wiring switch tracks to the AIU with Common to IN is because, if you wire Hot, automatic non-derailing mechanisms will cause a short circuit when triggered, instead of throwing the switch.

The mechanism uses the bridging of an outside, Common, rail to the control rail to operate the switch.

If your switch track doesn't have automatic non-derailing operation or it needs to be wired and you choose not to do so, you can wire Hot to the IN terminals. However, it is somewhat "against the rules".

This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!

Joe, I suspect you could revise your wiring without much effort, by switching the AIU/controller feeds from a hot terminal to a U or equivalent, and at the turnout by running a hot feed around the layout and tying to it the switch terminals now connected to ground.  If you already have a ground feed from U for all the switches, simply move it to a hot terminal.

RJR,

I tried doing that.  On the particular group of switches I have some G1000 switch machines and some twin coil NJ machines.  When I turned the power on one of the G1000 machines started chattering(going from normal to reverse continuously).  With the ground to the machines and the power at the push buttons things work ok.  I'm pulling what hair I have out trying to figure why it don't work.