The intent of this Post is to minimize or eliminate research effort by others.
After much research and investigation related to my KW - Whistle incompatibility issues with Locomotives from the Lionel Fun Dimensions and Richard Kughan/Neil Young eras, I discovered the fundamental problem was related to an error in the schematic of the original KW Service Manual.
After replacing my original Selenium Disc Rectifier twice, I subsequently replaced it with a 40 Amp NTE5944 Stud mount rectifier. (Overkill but above the built-in circuit breaker trip value.)
Note: the NTE5944 I used is a “Cathode to Case” Diode. You may find it easier to use an “Anode to Case” Diode such as the NTE5991.
At time of replacement, I followed the incorrect schematic for anode and cathode orientation and connection of the diode.
However, the orientation of the diode in the schematic is incorrect (i.e., the anode and cathode connections are reversed). Therefore, by following the schematic, I had created my whisle issue.
For my own use, I have revised the Original Service Manual and have attached it for others if interested. The attachment includes a Revision Cover Sheet that documents my changes.
I what to acknowledge and thank two Form Members that provided the “key” to finding the solution my problem – ADCX Rob and Ken Wing.
