Electrical HOT Smell

I believe you can still get the control boards for the ZW from some parts dealers, and Dale Manquen also repairs them I believe.

If that's not an option, I'd probably consider selling the bricks and getting something like the ZW-L or even a Z4000.

I got a rough quote for a board of $150 and $60 for installation. Because i am just running the transformer for light, what do think about finding a used ZW on eBay?

As usual, you folks are an outstanding resource. I have a meter on my ZW and I noticed that with all resistor controls (4 channels) in the off position I was still getting a 0.01 amp draw on the system. The draw seemed to be related somehow to the Atlas O uncouplers, the tracks are energized with two 180 parallel bricks direct to the tracks. 

Anyway, I moved the yellow layout uncoupler wire from a terminal on the ZW to a positive connector point on the track but left the ground side connected to the ZW. The mysterious amp draw was gone and so too was the heating, cracking, snapping inside the ZW. So, the only question remains, do the uncouplers running 18 volts have the stamania    to survive on 18 volts?.?.

Did a button stick and cause the coil to short?  Normally I run the accessory track activated devices on a separate power line that is phased with the train power and at a lower voltage.  Normally around 12-14V.  G

The uncouplers will quickly melt and warp with 18 volts on them for any length of time.  However, they draw more like an amp or more when energized, so I don't know exactly what you were seeing.