We have heard plenty of talk about the chopped sine wave output of the new modern ZW transformer but what does it really mean?  What does it look like on an oscilloscope? What affect does it have on new and old engines?

New ZW’s have had some bad press lately on some of the forums. Some  claim that the chopped sine method of regulating the voltage output causes a humming noise in TMCC engines. Others claim that the handles are fragile and that the mother board is subject to failures.

The handles are not as robust as old ZW’s but they seem adequate to me. I have replaced plenty of Postwar ZW handles too. The original modern ZW gear handle brackets were weak but replacements are available from Lionel. Newer versions of the ZW don’t seem to have this problem anymore. Early versions of ZW mother boards seemed to fail more often than they should especially in the model that came with the 135 watt bricks. I bought one of these purposefully  with a bad board at a greatly reduced price. The replacement board was $100 direct from Lionel and was a quick fix. A friend of mine was having  intermittent TMCC issues with his new ZW. I opened it up and found that the antenna connector had worked its way loose. Problem fixed! It’s a long trip from China and connectors can be jostled loose over the long voyage. See the photos below.

Chopped sine. In the photos below I captured the straight sine output of a 135 watt brick to compare it with the ZW chopped sine output of the same brick. I have no problems controlling any of my newer TMCC, PS1, or conventional engines. These include Lionel, Lionel Odessey, Digital Dynamics and TAS TMCC equipped engines. My oldest TMCC engine is a NYC NW2 switcher. It does buzz slightly on the new ZW. See the photo below.

Please leave comments and questions.

Tranz4mr