Problem with MTH SD70ACE w/PROTO 2

PS2.0 diesels w/3v system prone to stalls on my layout, esp. through straight side of Lionel, but not K-Line, O-27 switches.  Yet, the exact same model in 5v will not exhibit the same behavior.  I think the roller pick-up hits against the bottom of the truck block, and causes a momentary power interupption; the 3v is sensitive to this, but the 5v is not.  Empiric, not confirmed.

 

There may be no power going to the front pick up rollers. You can tell by with power on lift off back of engine with just the front roller touching track and see if engine shuts down.

Try cleaning pickup rollers especially between pins and rollers.  Also if the screws for mounting the wire to the pickup roller on the inside of the engine are black oxide vice stainless, you could have a continuity issue and need to replace screws or scrape off the coating.  Not sure why fwd is the problem direction.  G

 I've also seen this and once was just a broken wire lead, and once was actually a pickup inside the truck without an insulator. The engine would do exactly as you described, only on switch legs going a certain direction and with the truck turning. It took a bit to find it. I was surprised it didn't trip the breaker.

 Has anyone had the wheels out? I've also seen wheels installed incorrectly by the users.

I have an MTH SD70ACe that would stall when going through FasTrack O72 turnouts back to back.  I found that two of the roller pickups (one on each truck) were slightly turned so they were not parallel with the bottom of the engine.  I bent them back parallel and now the engine will go through them without stalling.  

 

Larry

I have problems with MTH engines going thru Gargraves switches as well, sometimes the engine jumps the track at the switch. It is ok with the postwar Lionel switches.

 

Lee F.