Is it practical to put BOTH your MTH PS2 GP38 and your MTH PS1 F-3 on the track? It's not to physically run them but to check the bell and whistle behavior when you apply power from the Z-750 transformer and controller. Or maybe you already did this.
I knew I had a Z-750 transformer in a box somewhere and I finally found it. To confirm, your Z750 transformer says 24V AC output (as opposed to 21V AC):
I'm not saying this is a problem but just like to put all the cards on the table so to speak!
Using multimeter set to DC Volts (red test probe to center rail, black test probe to outer rail):
- Don't have a GP38 but put a PS2 diesel on track. Set throttle to half-way of range. Engine starts up.
- DC volts bounces around but measures less than +/-0.2V DC.
- Press WHISTLE. DC volts bounces around but between +3.5V to +4.5V DC. Horn blows.
- Press BELL. DC volts bounces around but between -3.5V and -4.5V DC. Bell toggles on/off.
