Buzzing on new WTIU

It's a known issue and has been reported.  Has to do with the ZW-L not using a pure sine wave.  I believe @MTH RD are looking into it.

@Anthony Rizzuto 041618 posted:

I have a Lionel ZW-L connected to a new MTH WTIU. I have the two variable channels set to fixed. The four throttles are connected, one each, to the four channels, the two fixed and the two varible set as fixed. The two variable channels give a buzzing noise, but the two fixed channels do not. It doesn't matter what throttle is connected to a variable channel, I get a buzz. Functionally all channels work. The problem is the buzz on the two variable channels set to fixed.

Sent a request to MTH explain and give solution

Just to be clear this is not a new issue specific to the WTIU.  My old TIU would buzz if I used it with my ZW-L as have some others.  So, I switched to bricks to power the layout.  I also tested with an MTH Z4000 and it eliminated the buzz.

Others have a ZW-L and have no buzzing.   Seems hit or miss with the ZW-L

I am still having problems with WTIU. One of the fixed channels blinks red now. I disconect the fixed out leads and it is still red. Turned off and on and with no fixed out connections it still flashes red. Is there ANYONE who successfully operates this thing with a Lionel ZW-L connected to it? I think I just wasted over $300 on something that may be useless to me.

@Anthony Rizzuto 041618 posted:

I am still having problems with WTIU. One of the fixed channels blinks red now. I disconect the fixed out leads and it is still red. Turned off and on and with no fixed out connections it still flashes red. Is there ANYONE who successfully operates this thing with a Lionel ZW-L connected to it? I think I just wasted over $300 on something that may be useless to me.

Have you tried a different transformer to see if the issue is the ZW-L or the WTIU?

Also, what happens when you disconnect the ZW-L from the fixed inputs.