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I recently bought an old Lionel layout that has 022 turnouts and an SC-2 switch controller.  The 022 turnouts are bonded to the train board by the ballast on the rails.  Independent 17 VAC power to the turnouts is supplied through the “booster pin”.  Most of the turnouts operated intermittently.  After some detective work and some difficulty in removing the switch machine covers, I determined that the problem with the turnouts was that their internal slide switches are dirty or corroded.  Because the turnouts will be difficult to remove from the train board, I decided to implement a temporary fix.  [Eventually I plan to change the track plan.  When I do I’ll remove the turnouts and clean the slide switches].  The temporary fix is shown in the figure.  I disconnected the wires from the slide switches to terminals A and B on the switch machine.  The reason for this was to prevent the switch coils from shorting to ground and being damaged when a train is sitting on the control rail of the turnout.  Then I put new jumper wires directly from terminal A to coil A and from terminal B to coil B.  As a result of this temporary fix, both lamps in the controller (these are LEDs) burn continuously.  All the turnouts operate very well with the fix.  On those turnouts where the slide switches are not dirty, the anti-derail feature still works.

Question #1 – could there be any unforeseen consequences of making these changes to the 022 turnout wiring?

The power to the SC-2 switch controller had been supplied through the wires from turnout #1.  Because the intermittent operation of turnout #1 made the power to the SC-2 intermittent, I moved the control wires from turnout #1 to position #5 on the SC-2 (now effectively making turnout #1 into turnout #5).  I supplied the power for the SC-2 from a “wall pack” through the 12 VAC port.  This works fine, despite the admonition in the SC-2 manual, “Do not use the wall pack or the separate power terminals on the SC-2 if you are using it to operate switches.”  Also, I had been warned, with the fix I implemented on the 022 turnouts, that if the SC-2 “sees live voltage on a terminal it may present a false trigger of ‘thru’ or ‘out’ when it should not.” But the SC-2 seems to work fine and I see no adverse effects on its operation due to the mods I made on the 022 turnouts.

Question #2 – are there any possible adverse impacts to the SC-2 because of the fixes I made to the 022 turnouts?

Eventually I would like to use all six positions of the SC-2 to control turnouts.  I’ve read in other forums that people have cut one of the SC-2 circuit board ground traces to disable the powering of the SC-2 from turnout #1.  Before I do that I’d like to understand exactly what cutting the trace does. 

Question #3 - does anyone have a wiring diagram or block diagram of an SC-2 or know where I could find one?

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Original Post

Switch wiring looks good to me.

The SC-2 is just a set of relays which parallels the switch controller. So ok too. The #1 position allows the SC-2 to get power from the switch coils which are a low impedance compared to the very low power requirements of the SC-2. The red and green lamps get their power the same way in the switch.

The common side of the power comes from the center "Ground" of the switch terminals. Cutting the COM trace headed toward the #1 set of connections, cuts that power circuit.

I've cut the trace of four of these and the SC-2 works well for 6 Fastrack switches. You can restore the cut trace just by inserting a jumper from "Ground" of the #1 connections to COM of the SC-2 power terminal. 

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