stan2004 posted:Lou1985 posted:….
So back to the hobby shop it goes. It is most definitely speed related. It was tested under DCS and conventional power under 35 scale mph and works fine.
I assume the first thing your LHS will do this time is to run it at >50 sMPH! Also, I assume the engine gears have been properly maintained-lubed.
Call this nit-picking, but the symptoms suggest a power related issue. Obviously, speed and power are intimately related. When you mention time-dependent behavior to get it back to "normal" operation, I think electronic component over-heating...as opposed to electro-mechanical component breakdown when reaching 50 sMPH.
So, two ideas if you're continuing down the DIY diagnostic path.
1) Run the engine without the passenger car load. For the same 50 sMPH speed, this reduces the power demand on the transistors, diodes, etc. on the PS2 board. If the shutdown speed increases to, say, 60 sMPH that would be a telling symptom. Or, if your tests were without load then add as many heavy cars as possible to make the electronics work hard to achieve the same speed. Then, if the shutdown speed decreases to, say, 40 sMPH that would be an equally telling symptom.
2) Pull the 12-pin harness from the PS2 board and run the engine. You will not get any smoke or sound since the volume control and smoke switch wires are on that 12-pin harness. But the engine itself should move fwd and rev. Does it still shutdown at 50 sMPH? This is not conclusive but could help isolate (or at least put your mind at ease) as to whether your wiring modifications are related.
To be clear, even if these tests shed new light, if it is indeed a component-related issue you will be hard-pressed to repair it yourself as the components can be difficult to change and MTH does not publish component-level schematics or parts lists. So it would have to go to your repair shop anyway.
Thanks for the ideas. The engine is properly lubed. Everything turns freely when rotating the motor (via turning the flywheel). I tried the 12 pin harness trick already and it made no difference. I will try the 1st test, running the engine without the load, and see what happens.
I wish I could figure out what component is bad on the board (if one is) and replace it. Lacking MTH test equipment or any schematic I'm unable to. If it is a motor control issue on the board does that normally require replacing both boards? That's pricey and, if the case, I may end up converting it over to TMCC/Railsounds as I have boards for that already.
The previous owner said that he never ran the locomotive for more than 10-15 minutes at a time and never over 35 scale mph. So he may not have know about the issue. I have two main lines so I usually run freight trains at about 30 scale mph and passenger trains at 70-80 scale mph. Operating sessions usually last 45 minutes to an hour, so nothing that should tax a locomotive.
