Right now I have one mainline. I am using the gw-180 from Lionel and using the 990. How do I connect this transformer to a second main line? This way I'll be able to use this for both tracks. Thanks
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As long as you are using Legacy control on both mainlines, just hook up the second mainline to the system in the way you did the first mainline.
Larry
Would I use the red and black terminals on the back that's says accessories? The red and black Saying track is already in use
You don't need the red & black posts(or that entire box/controller) at all if you are all command.
The PH-180 transformer/brick can connect to the track without it.
If you are already using the controller for track power, connect to the same two red & black track posts as for the other line. There is no limit to the number of connections you make here(until you run out of physical room).
Bingo:
If I correctly understand your question:
Accessory voltage is too low to run track so no don't use these
1. If the two mainlines are electrically isolated then run power and ground from the transformer to a terminal board then connect power and ground at various points to each mainline in the standard manner.
2. If the two mainlines are electrically connected you don't need do anything other than connecting power and ground at various points in the standard manner. One set of power / ground from the transformer to the terminal board then branch out from the terminal board to various points on the track. You can buy inexpensive terminal boards 8-12 position from Radio Shack or even a Lowes, Ace, Home Depot etc. or order an MTH 11 or 22 position terminal board. The MTH has both power and ground lines internally connected so you need only run wire to and from the terminal board. With the Radio Shack etc boards you will need to purchase shorting bars (two - one for power and one for ground).
Added note - If you are running two electrically isolated mainlines it would be much better to purchase an additional transformer. With separate transformers running each line if you have a short on one mainline it will not affect the other line. Simply connect the ground wire form the 990 base to each ground on both terminals.
I didn't realize the GW-180 accessory voltage was programmable. I never used this transformer. All the ones I have used had set voltages of around 14 volts that one could not change.
I use two bricks cross-connected thru to (the TIU as I use DCS as well as Legacy)then out to the two mainline tracks.
This way if I have more engines on one line than the other more amperage from both bricks goes to that mainline. Otherwise if the tracks are independently connected to a brick each, the amperage is limited to the one line.
One problem I see with that logic is the two 180 watt bricks can far exceed the maximum power through one TIU channel. The TIU channels are maxed out at 12 amps, and running upwards to 20 amps through them is asking for major problems.
John
I thought that too but my LHS (Chicagoland Hobby) has a setup exactly as I described it and no problems so far.....
The operative words are "so far". I would certainly not do that, as I've seen what happens to a TIU when it's overloaded.
How are they cross connected? Two bricks in parallel feeding input of one TIU Channel?
Just thinking out loud here, but there are internal inductors that the current flows through. If you start pushing well above the amperage limit they can overheat, damage the insulation coating, loose their inductance and kill the DCS signal. Also the traces are rated around 20amps.
I imagine if you never really get over the 10 amp limit of one brick you would be ok, no derailment that causes a higher current short.
I wonder if running two fixed channels in parallel with one channel DCS off would be a better method. That way each channel is limited to 10amps despite the overall 20 amps to the mainline. G
The "so far" is what 10 years. The cross- connection was done by an MTH certified tech so again this was not without some thought.
Well, I can't imagine why a certified MTH tech would knowingly exceed the ratings of the TIU channels, that's a whole different topic. I question what thought process would lead you to believe that a 100% overload potential on a channel is a good idea. However, since we've discussed the issue and you've made your decision, no point in beating it into the ground. I'll let you have the last word, I'm outta' here. 
