I need some advice / expert help.
I have four mail lines running with MTH star wiring pattern in each line. One of my Z4000 transformers is showing a short in the line. After two days of diagnostics I have determined the problem is on one of the variable channels of the TIU. I checked the fuses in it and all are good. That's the extent of my ability. Is there a fix to the tiu? Is it worth it?
Your help is appreciated.
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yes could be a minor issue many times the TVS diodes short on the input or output of your tiu take a ohm meter with your vom volt (ohm meter) and look for a short with the tiu totally disconnected from your layout and transformer ,ill bet you have a shorted on your tiu output. test your variable channel you supect and youll probavly find a dead short which will cause your z4000 red short light to light! the TVS diodes are very cheap to replace, if you don't feel confirtable replacing I would be glad to replace it for you, if your good at soldering you can due it your self! I'll post a picture so you can see where there located!
Alan
https://www.digikey.com/produc...E3-54GICT-ND/2407434
No fair using my picture Alan. 
Well Thank You Alan. I'll let you know how it works out when I can get back to it in a week or so.
I have the same problem- Dead short in fixed output 2. The TVS diode has a dead short. I received replacement diode from Digikey, but having issues getting circuit board out of TIU shell to solder new one in. Any thoughts?
What issues getting the board out? You have to loosen ALL the terminal nuts, then the board lifts right out.
I'll give that a try- Thanks
That worked- I replaced the TVS diode for fixed channel 2 and I'm back in operation. Thanks gunrunnerjohn
Love the easy one. 
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