Anybody have a photo showing the surge protection diode on a MTH Z controller circuit board. or tell me location.
Do you mean the TVS? Photo below shows a Transient Voltage Suppressor (TVS) diode connected between the Hot (Green) and Common(White) on a plate-jumpered distribution strip with capacity for routing protected railpower from a PoHo 180 to various scattered soldered connections in a single power district.
This particular T-strip feeds from 5 protected hot and common T-strip screw heads to five different 37" lengths of Gargraves flex track in an oval. Other T-strips at different locations on the layout also suppl railpower and protect the fragile locomotive components from voltage spikes while routing railpower to other center and outside rails.