PS2 Engines Not Found on Gargraves Track

@DMiller17 posted:

Hi Folks - the subject really states the  issue. I've got PS2 engines that will not show up on my MTH DCS app or DCS Remote on any section of gargraves track I have. If I put a PS3 engine on it, it shows up just fine with zero issues. If I take the wiring I have going to the gargraves track and put it on lionel fast track then the PS2 engine shows up just fine. It's brand new gargraves track, I've tried wiping it down/cleaning it to see if that made a difference, but nothing. I am completely stumped and would appreciate any suggestions folks have. Thanks!

When we see this situation, where a PS3 engine is seen and works in DCS and a PS2 engine is not seen and not working in the exact same section of track- we have to go back a a KNOWN difference between PS2 and PS3- and that is, PS2 is polarity sensitive on the DCS signal.

Yes, I know the power is typically AC- however, the DCS signal convention is- red (AKA hot) to center rail, black (common) to outer rail from the TIU posts.

If somehow that polarity is swapped, then the PS3 engines work because they do not care about signal polarity, but PS2 doesn't work.

Also, Gargraves and other tracks do not natively connect both outside rails to each other in common. Fastrack has the shorting bus plates on sections that DO connect the outer rails. This matters because some 2Rail/3Rail capable MTH engines need both outer rails to be common for best electrical pickup due to the wheels and axles being isolated for 2 rail operation. So again, with Atlas, Gargraves, and other tracks that do not natively connect the outer rails electrically, your bus wiring and rail joiners or other methods need to form that common bond between the outer rails.

@Mark V. Spadaro posted:

Vernon - besides the box flap stating 2R/3R switchable, is there any other way to tell if a PS2 has this feature? I don’t believe I have any PS2 like that, but would like to know. Thanks.

Easy- with a meter- check for continuity between 2 wheels of all the axles. In a 2 rail capable engine, they would be isolated. On a 3 rail engine, they are always shorted just for the simplicity of construction. It takes time and effort and special parts along with a lot of specialized design to effectively isolate for 2 rail.

Also- mostly and maybe exclusive to Premier engines. I do not think Railking (being smaller and more typically budget class) had 2 rail capabilities.

Vernon, thank you! I swapped the posts coming out of the TIU and this worked for finding the PS2 engine. I guess I am still slightly confused though as to why the PS2 engine with the original wiring was still showing up on the lionel fast track. Even if both outer rails are connected to the negative, shouldn't the polarity issue still stop me from finding them? What am I missing?

@DMiller17 posted:

Vernon, thank you! I swapped the posts coming out of the TIU and this worked for finding the PS2 engine. I guess I am still slightly confused though as to why the PS2 engine with the original wiring was still showing up on the lionel fast track. Even if both outer rails are connected to the negative, shouldn't the polarity issue still stop me from finding them? What am I missing?

Correct, reverse wiring would ALSO affect any track system, including fastrack.

I would just go back and carefully trace your wiring, it's an easy enough mistake to make. AC power mostly doesn't care, but DCS signal matters and you just sort of found that out the hard way.

Connect the positive on both sides of the track. Those tracks are isolated on Gargraves track.

Scott Smith

For Gargraves track & RCS switches, do I put a common on both sides in one place for each loop OR at each drop point for the power?

Thank you.

Paul

@Railrunnin posted:

For Gargraves track & RCS switches, do I put a common on both sides in one place for each loop OR at each drop point for the power?

Thank you.

Paul

I'm of the belief at each drop point, however truthfully anywhere works. You are making redundant connections and every bit of that reduces voltage drop, increases reliability of electrical distribution.

Thank you Vern.