For the sake of this discussion, please assume:
HOT lead = “A” terminal on my ZW = center rail on track
GROUND lead = “U” terminal on my ZW = outer rail on track
Things didn’t go as planned when I tried to wire my used-but-new-to-me ITAD to a Lionel PW 145 gateman. Long story made short, I discovered that the ITAD is internally wired such that the NO (Normally Open) relay contacts, when activated or closed, supply HOT voltage, not GROUND. This seems to be at odds with the “standard activation methodology” employed by many accessories of completing a ground, not providing HOT power.
To prove my point, I wired a lamp to the ITAD’s NO and COMMON terminals, and sure enough, when the ITAD was unblocked, the light was off – when blocked, the light turned on. I tried the same with the NC contact and COMMON – as expected the light was on when unblocked and off when blocked.
I have searched the MANY ITAD discussions on this forum and they all seem to allude to the NO terminal being switched to GROUND when activated – that is NOT what mine does. What am I missing? Is this the way it is supposed to be? I thought there might be a jumper to reverse the center relay contact from HOT to GROUND, but I don’t see one. And as noted elsewhere, MTH schematics are not to be found, and their documentation is sorely lacking on this sort of detail.
I would appreciate any insights...