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Reply to "DCS Signal and Layout Common Ground Question"

Originally Posted by Barry Broskowitz:


Would you power the TIU separately, or let the Fixed 1 input power it?  I'm only using Fixed 1 at this point.

I would use a separate power source, including aproperly connected 14 volt Z4000 output, for powering the TIU.

Looks like you can't count on even separate leads from the same transformer being in phase!!

Yes, you can. I've never heard of a Z4000 whose outputs were "out of phase with each other."

Evidently the 18v and 14v outputs in the Z1000 are out of phase!

First of all, there is no "18 volt" output from a Z4000. There are a pair of 5-22 volt variable outputs, a 14 volt fixed output and a 10 volt fixed output, all of which are in phase with each other.


What you did was create an out of phase condition by connecting the Z4000's Hot (red) 14 volt terminal to the TIU's Aux. Power port's Common connection and the Z4000's Common (black) 14 volt terminal to the TIU's Aux. Power port's Hot connection. If you reverse what you connected form the 14 volt output to the Aux. Power port, all will be fine.


This and a whole lot more is all in MTH’s “The DCS O Gauge Companion 2nd Edition", available for purchase as an eBook or a printed book at MTH's web store!



I did not do what you suggest above. I've been referring to a Z1000 transformer, and you've several times referred to it as a Z4000.  I know very well what the outputs of my transformers are - the trick is to find what's in and out of phase.


The Z4000 outputs are all fine and in phase.  The only thing the Z4000 was connected to was the fixed1 input to the TIU. 


I used a SEPARATE Z1000 BRICK for the 14v accessory and AUX power supplies.  The 14V from the Z1000 went to track accessories, and the 18V (with concentric plug) went to the AUX pwr of the TIU.  That is when I discovered that commoning the grounds revealed that the fixed 18V from the Z1000 brick was out of phase with it's own fixed 14V accessory output.  The MTH Z1000 brick has a fixed 18V 100W output on a cable with barrel connector, and screw terminals for a fixed 14V 80W accessory output.


What I discovered is that commoning the ground of the 14V output on the Z1000 with the variable output on the Z4000 (track power) was OK, since they were both in phase.  Also plugging in the fixed 18V output of the Z1000 into the Aux Pwr on the TIU caused the 20A fuse in the TIU to blow. 


Using still a third transformer, a MTH Z500 with fixed 18V output only as the Aux Pwr input for the TIU was also fine.


This all tells me that the fixed 18V output of the Z1000 was out of phase with its own 14V accessory output.  I can verify that when I have time, but for now, problem solved.

Last edited by tk62
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