So my engine seems to have gone runnaway train...it just speeds up crazy fast to derailment speed, with ZERO throttle response, and after grabbing it, the horn blasts nonstop (without triggering it). Clearly the citizens of my Carpet Central were terrified. ....I have little doubt its an circuit board failiure of some kind, any way to narrow it down before this unit gets relegated to parts??
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Do you have a Roadname or product number. At some point Atlas started putting EOB in their engines. The tach reader could be bad. Though the horn running continuous it sounds like it’s not that.
I assume you are running this in command.
Yes, its item 1220, Santa Fe #90. Correct running in command (cab2) other locos fine so assume its not my system. I opened it up and nothing looks 'fried'. From left to right I think I figured major components (entering boad# in online search) - smoke unit , reciever board, railsounds, railsounds power, all mounted on top of motor control board??
There are tach stripes on the one motor in the picture. There should be a tach reader somewhere on that motor. Check to make sure there are no broken wires going to it and that it hasn’t separated from where it was mounted.
One note, it looks like at least one wire was pinched that goes to the shell (probably for lighting), check it closely to see if there is any exposed copper. If there is, it might have shorted and took something out in the electronics.
SO....since this topic is about an Atlas product, I moved it to the correct forum.
Top suspect is what Bob said, the tach reader wiring, it breaks right at the base of the tach board that's mounted on the motor. Easy fix as a rule. Next, check if the board sensor is positioned correctly and about 1mm from the tach wheel.
Thanks, no obvious disconnected wires but agree something happened that is not good in the electronics world. These trains are more complicated than expected...I bought it used and it ran for a while, so it will likely become parts + dummy unit. Oh well, can't win them all in this hobby. Most of my Atlas fleet has been reliable, but some of these 20 years old....
The reader looks to be about right for position 1mm and unlikely it moved (but not impossible?) I test ran it again and same story, races off after addressing no throttles control. I originally took it apart to reposition a window that fell out (wishing I hadnt now) so I likely did something to it. Have to say taking these apart was frustrating to say the least - lamp and antenae wires everywhere just waiting to be broken.....I do wonder how these are assembled in the 1st place without breaking something! I will just give it a rest and maybe a fresh look another day. Without diagnosis and spare boards etc, feel like the average modeller is out of luck repairing these....
If you address and start up the engine and it doesn’t take off. With the shell removed. If you can turn the flywheel by hand. Pretty sure there is a red LED that lights up on the board each time a flywheel stripe passes by the sensor to verify it’s working.
You also should be able with some button pushes disable the cruise. The EOB install manuals are available in the TMCC section of the forum.
Ok thanks, no red Led to be seen by striped flywheel? I tried turning off the cruise switch, but that did nothing. I do suspect an issue with speed control. Will next try disabling cruise once I figure how to do that.
Correction there is a red led by flywheel
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