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     I have tested three Lionel tenders on my layout. I run them on an oval of track with a ZW transformer. When I throw the throttle to start the steam loco (a postwar #736 or 685), the whistle relay activates, continuously sounding the whistle as the train operates. Is this a transformer issue or a tender issue. The whistle should operate only when pushing the whistle button, not the throttle.

Thank you for your assistance,


Original Post

The whistle relays should not activate with the ZW throttle being moved. It sounds like the whistle button may be stuck. Try hooking up the track to the opposite throttle and see what happens. If the whistles still blow, you have a DC voltage somehow getting to the track.  Get a voltmeter set to DC volts and see if there is a DC voltage on the track with the throttles on.



A much simpler test would be to swap throttle channel - if you are using A-U to power your troublesome track, try using D-U to see if it behaves the same. If it behaves differently (and correctly), you'll know for sure that the whistle circuitry for the initial throttle channel at fault. At that point, you can use the ZW service diagrams that Olsen's kindly hosts as well as @Tranz4mr's awesome webpage and inspect/replace the circuitry such as the whistle diode or rectifier plate. You might as well also follow up and checkout the whole transformer too!.

As an aside, Olsen's also has tender whistle service diagrams too, but I initially suspect your fault does not lie within.


Last edited by bmoran4
@Rob English posted:

Relay can be stuck in closed position.


Definitely a well known issue, but to have it happen on 3 tenders concurrently would be a statistical anomaly in my experience, hence my suggestion to look at the transformer first... Also, initially swapping the ZW throttle channels to the track requires no tools or opening anything up and can narrow things down.

Besides the valid issues with ZW whistle switches stated above tender and diesel whistle relays can have issues too. It seems sometimes the contact plate that pulls up in the whistle relay can get magnetized and stick. One suggestion is to add a piece of non conductive tape to the bottom of the magnetic coil between the contact plate and the bottom of the coil. Sometimes this helps sometimes it doesn't

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