Question on ZW 275W transformer and whistle operation.

[Anonymous]

I have the PW ZW 275W transformer and I've got a question about the whistle operation. I have a 4-6-4 Hudson with sound in the tender. The Husdon (model 6-28637)has the "RS" rail sounds. When I use the whistle control on the ZW it will blow but the engine slows down. I'm sure this has been covered previously but forgive me as I'm new to this board. The transformer works fine otherwise but I'm curious if there is anything I can do to rectify this. I have the CW-80w Transformer and with that one everything is fine.
Thanks for your time,
George

[Blueberryhill RR]

Hi George...Welcome to the Forum
I, also, have a 275 watt ZW. I rebuilt it ,but not the whistle circuit.
Try the other whistle button. You are probably connected to
Post A, now. Connect to Post D, and try it. I noticed on mine, that you have to pu***he button all the way over, to get it to put extra current out to compensate
for the whistle. If this does not work, then you may have to replace the whistle
circuit, which I am not an expert on.
Good luck.
Chuck

[lionelsoni]

The ZW has two completely separate whistle circuits, including the 5-volt windings on the transformer, which should be boosting the voltage when you blow the whistle, to compensate for the loss through the rectifier. Do you have the same problem with both sides of the transformer?

When you work the whistle control, it first replaces the direct connection from the roller with the 5-volt winding in series with the rectifier. This gives a strong DC voltage intended to operate the whistle relay. But the motor will slow down. Then, as you move the control farther, it should connect a 1.5 ohm resistor in parallel with the rectifier to get the voltage back up to a reasonable level, with only a small DC component to keep the relay closed. If you work the control quickly enough, the train will not have enough time to slow down while the control is in transition.

The symptom you report is consistent with the second contact's never closing or with the resistor's being open. However, it seems unlikely that this would have happened to both sides of the transformer. Is it possible that the transformer has been modified?

Here is the circuit:
http://pictures.olsenstoy.com/cd/transfmr/psvw1.pdf

[Blueberryhill RR]

Lionelsoni..... I don't know about George, but I appreciate that detailed
answer you gave. Now I know the facts. Like I said, I'm no expert, but
I have found, what you said, to be true. Pu***he control quickly.
Chuck

[waltrapp]

Bob, your knowledge of all things trains amazes me. You (and others) have my total respect.

- walt

[Anonymous]

Thank You for the welcome everyone. I've tried both sides and it does it with both sides. The one deviation from your comments about pushing the whistle control all the way is if I do the lights on the engine do glow brighter, the engine speeds up but no whistle. If I pu***he whistle controller forward but "ONLY 3/4 of the way" then the whistle blows fine but the engine slows. I don't know if it has been modified or not. I tried to print out that PDF file but it won't let me print it. Anyway I can get a copy I can print?

[lionelsoni]

That's interesting. The rectifiers must be working or the whistle wouldn't blow in the first place. But when the control goes all the way, the DC component in the track voltage either disappears or diminishes to the point that the locomotive does not recognize it, although the total voltage increases as it should. That would happen if the 1.5-ohm resistor were too low in resistance, including short-circuited. This is a modification that I can imagine someone's doing, to get a voltage boost without the whistle's blowing, while tolerating or manually compensating for the slowdown when blowing it with a partial actuation of the control. It is also possible that both rectifiers' resistance is too high; but, again, it seems an unlikely coincidence.

Do you have a locomotive with a relay-operated whistle or horn? Will the ZW work properly with it?

[Anonymous]

Unfortunately no, both of the engines that I have that whistle have electronic whistle circuits. The Hudson and a brand new steam switcher engine that Lionel recently came out with. So are you suggesting that I check the resisters on both circuits to see what they read?

[okiechoochoo]

Speaking of postwar ZWs, I noticed several in the new TCA and LCCA listings that were rebuilt excellent condition for $175 or under. I remember when these were at least $250 or more. Price seems to be dropping like a rock. I think most folk want the newer transformers for the new electronic locos.

[Anonymous]

I got this one for $150.00. All the rollers and everything look really good. I'm just stumped on this problem with the whistle situation. It's not such a major thing but an annoyance I guess.

[ChiefEagles]

I got one that was reconditioned for $150. Had different whistle compontents. The guys is a tec and he told me they were the "new type" [? bet Bob knows what he was talking about]. Blows conventional postwars and they never slow down. Seems to be finicky on the new stuff like Polar Express. When I run the new stuff [electronic whistle trains and PS1], I use my DCS remote and they work fine. Maybe yours has been converted like this one I have. Postwars seem to run better without DCS remote and just use transformer to vary voltage and whistle. Does not bother me as I mainly run command [TMCC and PS2 engines 90% of the time] and this ZW works great. I have two KW's and seems like to me that the new electronic whistles did not work good with them either.

[Anonymous]

Thanks for all the replies everyone. I guess I can live with it for now, I'm using my VW-80W for my 4-6-4 Hudson with Rail Sound, it works it fine, I am going to use the ZW to power the new switcher engine, since it doesn't do allot of distance moving on the side spurs which is where it mainly sets then the slow down isn't much of an issue. I was just curious as to why it acted this way. From all the responces I'm learning it's just the difference in technology I guess. The ZW also runs my 1862 General set on a seperate track but it doesn't have a whistle car. I'm going to try and purchase one and then I'll see how it acts with that car and the ZW transformer.

[lionelsoni]

If you can, I would suggest that you check the resistors. Even if they are the right value, you might just need more DC in the holding position for the new locomotives. You could experiment, if you're handy with a soldering iron, by removing the resistor from one side and connecting it in series with the other one, to get a total of 3 ohms. That will surely unbalance the waveform more, increase the DC component, and might be enough to keep the whistle blowing. If it works, then you can start looking for 3-ohm resistors.

The fix that was referred to as the "new type" was probably replacement of the obsolete copper-oxide rectifiers by silicon ones. If your problem is due to deterioration of the rectifiers, it is not very hard to replace them with silicon. The biggest rectifier that Radio Shack sells is rated at only 6 amperes, which may be a little puny for a ZW: $2.49 for 4, 276-1661. I would use something around 25 amperes, but the Radio Shack ones would be fine for testing. You wouldn't have to remove the copper-oxide, just connect the silicon one around it.

[Anonymous]

Thanks Bob, I'll check the resistors out and see what happens.