1. Normal 027 tubular track setup on a small 4 x 8 layout (inner and outer loop), Lionel postwar 2026 engine and 6466W tender, KW transformer
2. Added a Lionel steam sound car which came with the #6-5906 sound activation button
3. All center rail track taps from the layout are supposed to route through the sound activation button (which they are) to the variable post (A) or (B).
4. I had replaced the whistle diode in the KW with a 6A10 diode as per these instructions
5. When the whistle handle was activated only the whistle in the tender blew (not the whistle in the sound car) and the bell in the sound car would come on. Every time. The engine sped up (as it is supposed to). The bell would continue ringing until the sound activation button was pressed for 2 seconds or more, or the whistle handle blown for 2 seconds or so. Button depressed for two plus seconds resulted in the engine slowing down or stopping because of the center rail drain.
6. Two of those diodes in a row blew (heated up and fractured with a burnt smell) after a week or so in between them.
7. Because two 6A10 diodes blew up, I Installed a 40A stud mounted diode instead (yesterday). 1N1186RA 200v 40A
8. Now both the whistle in the tender and the sound car are activated simultaneously with the KW whistle handle and the bell is activated with the #6-5906 sound activation button. ??? And when the button is pressed the engine slows down to a crawl or stops as before. If you run the engine at high speed (which I hate) you can hear both whistles. Slow it down and you hear the 6466W tender whistle motor laboring and the whistle in the sound car dominates. There is a lingering of the sound car whistle (maybe that's normal).
9. There is no difference and has not been if I reverse the sound car on the track.
I am concerned that with the heavier duty 40A diode other components will burn up instead. What am I doing wrong?