The lighting load of the PW must be considerable. I tested it with a 1.4 amp output wallwart, and the inside lights dimmed when the sign flashed. I don't use the Menards wart because I don't want 120 volts running around my layout. I'll be using AC/DC buck converters hooked to my 18-volt accessory feed and outputting 4.3 volts.
Menards ought to have such as alternate power sources.