MTH TIU does not work/red light is off - but unit has power to fixed in (1)

If the red LED isn't lit then the TIU is not getting power for its own use.

The TIU always passes track power straight through both Fixed #1 and Fixed #2, however, if the TIU isn't powered there will not be a DCS signal at the channel's output.

Three questions:

• Is there anything plugged into the TIU's Aux. Power port?
• Has this TIU ever worked?
• If the TIU has worked before, what's happened since the last time it did work?

hi - there is nothing plugged into the TIU Aux Power port

the TIU did work the last time i had turned it on

nothing happened since it last worked - is in the same place - did not move or change anything - i did open it up to check fuses - 

I was going to add a wifi unit - but did not get the red light on - so i never attempted it 

any ideas

 Try an AUX power supply.    Even a Lionel command base wall adaptor should light up the tiu temporarily  if you have one.

Do you have an Aux power supply?  Worth a shot.

thanks - i just tried the Lionel Base power adapter - plugged it in and no red light- ugh don't know what happened - thanks for the post

I also have tried an aux power supply - still no red light?  is there any thing i can check internally to see if power is getting to the right spot

Based on all of the above and the stated symptoms, the next step is a trip to a repair tech.

Barry - thanks - have been reviewing your 3rd edition book - but i think i need to bring it in - appreciate the help -thanks 

My problem is similar, in that I've had no issues with the TIU, but now every time I plug the 110 line into #2, it blows a 20-amp fuse immediately. I did take apart the connector, and it looks fine. no apparent shorts. very maddening, as this unit, although 3 years old, is not heavily used. Thoughts? I'm pretty much resigned to bringing it to the shop, but my fear is that the unit is fried, for some unknown reason. Very vexing...  Thanks, any opinion is welcome.   Grandpa Jim, Chicago

Grandpa Jim posted:

My problem is similar, in that I've had no issues with the TIU, but now every time I plug the 110 line into #2, it blows a 20-amp fuse immediately. I did take apart the connector, and it looks fine. no apparent shorts. very maddening, as this unit, although 3 years old, is not heavily used. Thoughts? I'm pretty much resigned to bringing it to the shop, but my fear is that the unit is fried, for some unknown reason. Very vexing...  Thanks, any opinion is welcome.   Grandpa Jim, Chicago

Are you saying that you are plugging 110VAC into the TIU? If yes, that would explain the fuse blowing. 

Grandpa Jim posted:

My problem is similar, in that I've had no issues with the TIU, but now every time I plug the 110 line into #2, it blows a 20-amp fuse immediately. I did take apart the connector, and it looks fine. no apparent shorts. very maddening, as this unit, although 3 years old, is not heavily used. Thoughts? I'm pretty much resigned to bringing it to the shop, but my fear is that the unit is fried, for some unknown reason. Very vexing...  Thanks, any opinion is welcome.   Grandpa Jim, Chicago

I'm confused. Which fuse are you talking about. The 110  20 amp fuse in your service panel or the 20 amp fuse in your TIU?

And #2 what?

I ended up sending TIU back to MTH. They repaired it not sure what they did but I replaced the wires from the output to track and have not had any problems   There must have been a short somewhere in the output wires there didn’t appear to be any problems but it’s working ok now.  

I also am using an 18v “m” plug power supply from radio shack to “power” the TIU.  Working fine