Modern air whistle won't shut off after KW diode upgrade

I had a thought right after I posted.  I tried the tender on my type V, with no whistle controller, and I get a whistle.  What causes this?  Thanks, Chris

It is a whistle problem.

Here is a complete discussion on the problem.

The replacement circuit board is available HERE.

I replaced My KW with a new copper disk i got from the Train Tender years ago . It was an easy switch and still  works well. I've also used the stud diodes in my ZW , I 'm probably one of the few but like the disk rectifier better. The track must be getting some dc to trigger the whistle, perhaps a lighted car might help? 'U connection  on KW  connected  to the outside rail?

The transformer is not the problem.

Gotta' go with Rob here, I can't see this being the transformer.  At the price that Bill has the board, it's an easy call.

Just replace the transistor, it probably shorted.  How does the transformer work with a PW tender whistle?  G

OK, thanks for pointing me in the right direction.  I mistakenly thought that if the board failed, I wouldn't be getting any DC to trigger the whistle, forgetting that things can fail open or closed.  Cheap enough fix.  Thanks, Chris

Ok I agree  Not transformer. I miss- read the post thinking the whistle   was OK  before the diode install.

The funny thing is the whistle was ok before the KW "upgrade".  And when I did the KW upgrade, I installed TVS diodes across AU and BU posts.  And last fall, I installed TVS in the whistle tender, between the tether wires.  So I don't think I fried it from a transformer spike.  I guess it was just time for the transistor to go, and just happened to be right after I did KW work.

I just ordered ten MPSA13s off ebay for less than $3 shipped.  These days, you can't even drive to the post office for that price.

The problem is with the non-polarized cap, C-1.

A quick fix that may work is to reverse C-1 or add a diode

in series with R-3 wiith the diode arrow pointing toward the

transistor.