Hi GUYS,
I just bought a MTH SD70 NS and have a problem with lurching at low speeds and motor getting hot after about 5 minutes of run time at a speed of maybe 50SMPH. My question is how far does the speed sensor have to be from the fly wheel? Could this be causing my motors to overheat? Thanks for your replies.
laz57

0.75-1.25 mm.

Overheating usually caused by binding or pulling too many cars, especially with too low a voltage.

Thanks for the reply. I'm taking to LHS for repairs, I'll let you know what the fix was. Again Thanks,
laz57

quote:

Originally posted by RJR:
especially with too low a voltage.

RJR's point is very important, laz. I recommend that you measure the voltage on the track WITH the engine operating with the typical loads. If you are measuring much below 15 volts -- for sure your PS2 speed control is pumping up the amp draw to compensate, and the associated heat.

What can you do?

• Make sure that you have good voltage thru the TIU; it does measure ~18v on the output side with no load, right?
• Assure that you have solid, low loss, connections/wires to the track; measure the track/wiring losses with no train load.
• Finally, you've got supply internal resistance -- the tendency for supply voltage to drop with load. This characteristic is related to, but different than, supply capacity. Some supplies are much worse than others.

Bottomline: look at voltage that yer engines see; the higher the better for low heat power.

-- gary ray

Thanks for the info GRAY RAY. I got in contact with dealer who sold it to me and is going to exchange it for me. But thanks for the info I will copy and save this for future use.
laz57

Just a thought on one I ran into recently. Please check the two wires going to the motor and make sure one of them is not slightly rubbing against the motor case.

GARY RAY,
I recieved a brand new engine from HS. I lubed it and ran it in forward and reverse at low med and high speeds. All ran good with no cars on it. I later put 8 cars on and the same thing happened. It ran for 45 minutes then motors got hot and the engine just stopped and shut off. I am running the TIU with a 180 watt Lionel power brick on each of the tracks. I checked the voltage to the tracks with load on it and it regestered at 16.8 volts. I guess its off to the MTH service station?
laz57