ZW horn lever and Hogwarts Express

[TrainLarry]

You may wish to upgrade the old whistle rectifiers with modern stud mount rectifiers. This may get the ZW to operate the whistle in your train.

Larry

[Benjamin Maggi]

Oh yes, the wires were switched and still no whistle.

[sulafool]

Did you try reversing the track wire connections to the transformer as Sir James said? Always try that first before doing all that  intensive testing with voltmeters, etc.

[Benjamin Maggi]

Well, I ran the tests as suggested above and the transformer performed fine per the Voltmeter. Still no whistle out of the tender though. Perhaps I will need to purchase a whistle button or something to wire between the transformer and the track?

[Benjamin Maggi]

Thanks Larry. I will try out these tests this weekend.

Ben

[fixall]

Also, for the whistle to work (assuming the transformer passes all the tests Larry describes), there has to be some load in the circuit such as the engine and/or a few lights as the whistle uses some of the current that is flowing in the circuit. Thanks Ken

[TrainLarry]

No.

We are talking both AC and DC voltage here.

Hook up voltmeter to A-U terminals. Set it to read DC voltage. Put a lighted loco in neutral, or a lighted car on the track.

Move the 'A' throttle all the way up.

Push the right hand  Whistle lever forwards. Part way up when pushing the Whistle lever, the voltage should read 4-5 volts DC.

Continue pushing the Whistle lever all the way forward, and the DC voltage should drop to 2-3 volts.

While keeping the Whistle lever all the way forward, observe the light in the loco or lighted car. It should be brighter with the Whistle lever all the way forward, than with the Whistle lever released. This happens because an additional 5 volts AC is added to the track when the Whistle lever is fully pushed forward.

Do the same with the 'D' throttle.

Hook up the meter to the D-U terminals.

Move the 'D' throttle all the way up.

Push the left hand  Whistle lever forwards. Part way up when pushing the Whistle lever, the voltage should read 4-5 volts DC.

Continue pushing the Whistle lever all the way forward, and the DC voltage should drop to 2-3 volts.

While keeping the Whistle lever all the way forward, observe the light in the loco or lighted car. It should be brighter with the Whistle lever all the way forward, than with the Whistle lever released. This happens because an additional 5 volts AC is added to the track when the Whistle leveris fully pushed forward.

The transformer should pass these tests for the Whistle circuits to work.

Larry

[Benjamin Maggi]

So, having the A/D throttles at the closed position, if I move them (one at a time) the voltage output should be increasing to 4-5v, then drop to 2-3v in the full position, then increase back to 5v at the full position? How can it be 2-3 and 5v both at the full position? Excuse my ignorance!

TrainLarry

Hook a voltmeter to the transformer A-U and then the D-U terminals, and set it to read DC volts. Turn up the 'A'  throttle, and slowly press the whistle lever forward. You should get a 4-5 volt DC reading with the lever partway, then the voltage drops to 2-3 volts DC at the full forward position of the lever. At the full forward position, there should be a 5 volt increase in AC voltage on the track also, as indicated by an increase in the headlight brightness on the locomotive. 

[fixall]

If the DC is not correct, then the rectifier is bad. I can replace them with zener diodes...I did 3 last week. If you have a special tool for ZWs then it is easier....don't have to take out the whistle switches. You can contact me thru my web site http://kenslionelrestoration.com/ Ken

[TrainLarry]

Hook a voltmeter to the transformer A-U and then the D-U terminals, and set it to read DC volts. Turn up the 'A'  throttle, and slowly press the whistle lever forward. You should get a 4-5 volt DC reading with the lever partway, then the voltage drops to 2-3 volts DC at the full forward position of the lever. At the full forward position, there should be a 5 volt increase in AC voltage on the track also, as indicated by an increase in the headlight brightness on the locomotive. Do the same for the 'D' throttle. This will verify that the transformer whistle switch and rectifier are working properly.

Larry

[servoguy]

Hook it up to A-U and report back what happens.

It sounds like the whistle control for D-U isn't working correctly.

[sir james I]

This works on mine.

Push the whistle button slowly to the halfway position. That's the only spot mine will work on a ZW. You could also try reversing the wires to the track.

[rtraincollector]

The older post war transformers won't work some of the newer horns/whistles as they take a different ( I think its called ) wave anyway its difference in the electronics sometimes if you do it slowly very slowly you can find a spot on the transformer were it will work all depends newer and older transformer are different Bob Nelson will probably come in and give a better explanation of the differences.   

[Benjamin Maggi]

For the past couple of years for Christmas I have run a Lionel O-scale Hogwarts Express train set under the tree. Today at a train show, I picked up an older Lionel ZW transformer (275 watt). I talked to the seller and the cord was replaced, the rollers were replaced, and it was cleaned. I hooked up the ZW to the train (using the D/U binding posts on the back) and the train ran like normal. I tried to use the "whistle/direction" lever and the train slowed significantly, but no matter which way I slid the lever the tender whistle never blew. I switched transformers for the Lionel CW-80 and the horn in the tender worked like normal. I looked online for an instruction manual for the ZW transformer but couldn't find anything. What am I doing wrong? Thanks.