MTH ALP 46 stalls in Atlas turnouts.

Glenn,

It sounds like the locomotive may only have power pickup on one set of trucks?

You don't mention where in the switch the loco stalls?I assume at or near the frog?   I would ensure that the closure rails are not in contact with what forms the wing rails in the frog, likewise, the rails on the heel side of the frog are not in contact with the rails which form the points in the frog.  Basically, the frog should be totally isolated.  Atleast with the Atlas #7.5 switches they do not put any non-conductive material between these critical sections in a switch and often the rails end up touching, especially when the weight of a locomotive rolls over the rails.  I am sure the same can be said for the Atlas #5 switches as well.

Sometimes you can take a flat blade screwdriver and gentley pry the rails back, some people cut the gap with a saw or a dremel tool.  For safe reliable operation I would also fill the gap with a styrene filler strip once you reopen the gap.  You can file the rail head profile into the styrene to ensure the flanges on the wheels don't get tripped up when crossing over that section of rail.  Once the frog is totally isolated I would also recommend powering your frog, this can be as simple as a toggle switch or push button on the fascia or you can often use contacts on a switch motor to change the polarity of the frog based on the switch direction.

Hope this helps!

Hi Glenn,  that sounds suspect possibly on the rails.  The frogs should have power which is switched based on turnout position.  Products out there like frog juicer are built for that purpose/

 I have two ALP46 both have 8 wheel pickups.  Have you tried running a continuity test on each sides of the trucks to make sure all the wheels on each of the sides complete a circuit? Are you running in pantograph mode?  I heard from another fellow modeler, the ALP46 in pantograph mode only one side of the wheels picks up power and the pantograph picks up the other–as opposed to all wheels picking up one polarity from from the rails pantos pick up the other..  

Okay,

So, I tested the wheels to see if all 8 pick up power and discovered that on ONLY one truck the wheels on one side are not picking up power.  This seems odd, so it is probably a defect.  I'll check the pantograph mode issue, but in the meantime, does anyone have any suggestions on how I could fix this, or would the ALP need to go back to MTH for repair.

Thanks for the help guys.

Pull the truck apart and check the wires for continuity.  The truck is simple to remove without removing the body shell.  Remove the side frames, then unscrew the plastic cover plate remove wheels then unscrew the truck block from the motor block.  In 2 rail mode the red wire (center pickup rollers) should be dead and the brown and black wires should be live for power pickup, you can test continuity to the other truck wheels which are making contact. If the wires are good then check the brown wire.  It has a spring to push the plunger onto the wheel bearing of the insulated side.  If all else fails go to a local MTH repair shop (easy) or send it back to MTH.