Unable to activate my HO layout

Model Railroader Electronics and DCC
1

Recently completed building Atlas Layout 102 (Trunk Line) from the book Atlas HO Beginners Guide, dated 1960, and using a MRC Tech 4 model 280 duel controller.

I have checked AC and DC voltages going to my switches and terminals. All is good.

Resistance checks indicate wiring is good.

I suspect that there may be a flaw in the Layout 102 wiring diagram, or I have missed something in my wiring. In the schematic it shows two individal controllers being used. One dc lead on one controller (lets call it “B”) is going directly to one side of my selector for the terminals. The other controller (call it “A”) has one lead going directly to the other side of my selector switch for the terminals. The unused side of controller A and B are tied together in a terminal block and one lead comes out and is designated common lead which continues to one side of track terminal #7. The other side of track terminal #7 goes back to selector switch #7.

Thinking my consist egines were faulty, tried all three individaully. No go.

Could the leads on track terminal #7 need to be reversed? Currently, the common lead is on the right side of the terminal and the wire going to switch #7 is on the left.

Track terminals 1 - 6 only have one lead, which go to the respective selector switches.

I did find one turnout selector switch that is bad (no AC on the terminals of the switch) which I am replacing. All other turnout selector switches are good.

Any suggestions?

2

Put your multimeter on the resistance scale and do a continuity check. It is not wise to completely build a layout without doing periodic continuity checks and watching for shorts . It sounds like you do not have a short at this time.

Rich

3

Atlas layouts built with their control switches end up with what’s called common rail wiring. That’s the two power pack wires goign to a terminal blocka nd then a single wire to one side of the track in section 7. That rail should not have any insulated joiners (unless there’s a reverse loop or wye) on the entire layout. Only the other rail should have insualted joiners, and make sure the wire from the Selector connects to the correct rail - if any of them are wired to the wrong rail it is a dead short when that block is switched on.

You need to find the problem first, but after that, you cna make things work MUCH better by wiring additional feeds to that terminal block fromt he common rail. Rail, and even more so, rail joiners, are not a great path for electricity. The Atlas designs rely on one connection tot he common rail to power the entire layout. Voltage drops and complete lack of power when a rail joiner gets dirty and fails to conduct properly are common - add the additional feeds on the common rail to prevent this.

–Randy