(I don't claim to be an electronics wiz)
1. VAR 1 input was throwing the circuit breaker (CB) on my 180 watt Lionel 'brick'(power supply).
2. insured the input power supply was in phase with other power supplies.
3. removed output wire on VAR 1 and still threw the CB.
4. Tried another input power supply to VAR 1 and still threw the CB.
5. Called MTH tech and he said it was probably the surge suppressor.
The surge suppressor is a diode (part #BB-0000033 at $3.60 each: got two since cheap and min order of 10 bucks).
The VAR 1 diode is the far corner one by the VAR 1 output plugs (each output has a diode).
1. removed the 6 screws on the bottom to release the top of the case (insure power is off).
2. Removed the suspect diode and put my volt meter on R and checked the suspect diode and the needle pegged to the right whereas the new diode stayed to the left.
3. Bent the new diode wires to align with the holes and cut off the excess wire.
4. Used some fine needle nose pliers to hold one wire (and also act as a heat sink) and soldered one side (did the same to the other side).
5. Tested and all is 'good in the world' again.
Note: I put the diode in with the marking on one end of the diode facing left (same as the other good diodes).
Interesting: diodes only allow 'juice' to flow one way but the new diode would not allow voltage (tested via the volt meter on R) to flow either way! The damaged one pegged the needle to the right in both directions.