MTH DCS Variable Channel Problem

You have likely lost one or more FET's in the variable channel, if they're shorted, you get full power all the time.  It's an issue that can be repaired, drop me an email and I should be able to beat it into submission.

Thanks You, any repair suggestions will be appreciated.

Replace the FET drivers for that channel, they're the four TO-220 packages that have the heatsinks on them.

Thanks again for the advice but your still talking above my head.  What do TO-220 packages look like and where are they on the PCB.  What are heatsinks.  Sorry, I can figure out and repair most mechanical loco problems but the newer electronic stuff is beyond me.  Where can I get TO-220's?  Would Mouser Electronics have them and should my search term be TO-220? 

Trust me, you don't want to attempt this repair job with your level of expertise with PCB repair.  You can easily destroy the board and need a new TIU instead of a repair.

What he said.  

But to answer your question, see the photo in this recent OGR thread about repairing a TIU.  Each variable channel has 4 identical TO-220 transistors.  TO-220 is not a part number but is the mechanical dimensions/size of the package ("TO" means Transistor Outline).  There are thousands of different transistors that come in the TO-220 package.

As the thread shows, the specific transistor used in the TIU is not particularly expensive (10 cents each).  But as GRJ says, it requires soldering finesse to effect a repair without leaving a trail of destruction!  

Thanks again for all the advice.  At least now I understand the problem.  I did not plan to attempt to repair the TIU as it is still under warranty.  I"m just disappointed with the quality of MTH products.  I thought I was buying a better mousetrap but ended up with a real dud instead.  I've had problems with everything MTH I have owned.  Just got a diesel back from warranty repair and their track and switches are not even worth discussing.  Live and learn but judging from all the issues in the forum, I'm not the only one.  Thanks again for meaningful explainations and advice.