I have a wiring question. I'm sure it's simple but can't figure it out.

If both transformers are still operating both sections there is still a connection somewhere. Did you install isolation pins at each end of each isolation section? Just isolating the center rail should work.

The fiber pins identify the two blocks, you are OK there.

"U" connections all go to Lockon clips #2 for outside rails.

Throttle binding posts "A", "B", "C", & "D" go to clips #1 on the Lockons as needed.

This may be thin but are you shutting down each tran separate to test?

i use this method in RC planes to have a separate battery pack for retracts. Common ground and sep hot and it works fine. 

I suspect something is making contact. Separate the track completely and run a ground to hook the two outside rails and see if that solves the problem, then work from there.

good luck.

I realize you've used transformers for this task before, but there are drawbacks with regard to potentially large fault currents between/among the A-B-C-D posts of your ZW when the trains traverse the two blocks. Instead, adjust your downgrade speed by powering that section with an adjustable rheostat Like the Lionel 95 or Lionel 81/Ives 1894 powered from the same transformer lever/control.  This will let you adjust the downhill speed accounting for differences in engines and loads.

If you have "A" set to 17 volts and "D" set to 7 volts, there is a difference of 10 volts, and the full amperage of the ZW(14+ amps potentially) that is bridged by every roller crossing the fiber pin between the two blocks.

It's worse when a double roller pickup on a loco bridges the pin, and gets worse still when a passenger car like the Polar Express cars with the rollers on each truck wired in parallel straddles the two blocks and the fine, small gauge wiring inside is asked to carry the current of a good portion of the running train... even momentarily.

Additionally, each bridging/unbridging of the gaps/blocks has the potential to set up transient voltage spikes going into the hundreds of volts which is damaging to sensitive semiconductors - maybe not immediately, but certainly cumulatively.

Using a rheostat or voltage dropping diode array eliminates the fault currents.

If it makes a difference, your wiring is wrong.

Assuming the wiring is in proper order some other things to check for would be, first, are you testing with illuminated cars? these will bridge the isolated section until the entire train is on it.  If that turns out to be the problem there are lots of "fun" ways to solve it.  

A second thing that comes to mind is if the fiber pins are installed right where the incline starts or ends, it may be that the change of angel is causing the tracks to touch, letting the higher voltage flow through.  Try pulling the tracks apart a bit ( 1/16 inch or so) to make sure the insulator pin is doing its job.  

Sounds like you have the common U posts connected to the center rails and the A & D posts to the outside rails. If so reverse them.  

If you are just running 1 train on the loop,all you need is to make 2 outside insulated rails. Have them activate a relay coil using the insulated rail method.  The relay will then switch the 2 throttles automatically from one to the other,depending on train position. I assume you want a 3rd throttle for flat surface running. That can be done with an additional relay.

Dale H

I worked that out before for someone else once. I will look for the drawing. I run a trolley that way. I have 3 voltages,uphill downhill and flat. I just wired it ad lib without a schematic.  As I remember I used 2 relay 24VDC DPDT with 10 amp contacts. I use bridge rectifiers as a voltage dropper,but you could use 3 transformer taps as well. The relays are activated by the outside insulated rail method,described here

LINK

Voltage dropping is described here

LINK

Insulated rails are on the uphill and downhill portion of the loop. They activate a relay for each section. 

The relay contacts switch the 3 voltages,either from transformer taps or from the voltage dropper. For simplicity ,we will call it -6,-3,and 0 volts reduction from the throttle.  . If the train occupies the uphill insulated rail,the voltage is boosted (0) by the block relay energized by the insulated rail. If the train sits on the down hill rail the voltage gets the reduced voltage( -6) by its block relay. If it is not on either one,both relays are closed and the flat voltage (-3) goes to the center rail through the NC contacts of both relays in series. . The contacts are wired so that both common contacts go to the center rail. The 0 and -6 go to each NO contact. The -3 goes through a second set and to the center rail. 

This is easier to make up than explain or draw. If I get time I will post a drawing if interested. I have a bunch of hospital tests this week so it may take a while. 

Dale H

Hope this is readable,found these in a file. Actually,I think it can be done with SPDT relays. click on photo to enlarge

Instead of 3 throttles a voltage dropper can be used

A bit of warning about what you are doing now. If your 2 throttles set at different voltages are somehow hooked together, you can damage your transformer and it is not breaker protected. Note the the relay contacts keep the throttles separated electrically from each other. I do recommend the wire wound resistors mentioned either. In a track short circuit,they can burn up,also not breaker protected sometimes. Also different locos will react differently at the same setting.

Dale H