The schematic Rob provided shows the resistor wire soldered to the cathode of the rectifier. That is the way it was before I bought the stud diode. See photo:
Two of those blew up. They were rated at 6A. Rob said they were backwards. The stud diodes I bought ended in RA that means the large metal part with the threads is the ANODE and the solder end is the cathode. Those are now in there and the whole thing is smoking from blowing the whistle. Some of the stud diodes people install are reversed with the threaded portion the cathode.
Which is right? In an AC application (like the original setup with the motorized whistle tender) I don't think polarity was an issue. The sound car is a modern device like the newer engines that have DC components so (as far as I know) DC polarity alternates between the whistle and the bell.
Also the 1033 center rail goes to the U terminal and on the KW it goes to the variable A or B posts so I am not sure about the schematic above when it comes to the KW.
I think.
