had to reset a decoder (C8 = 2) when the headlight was controllable but the wheels wouldn't turn. I resoldered the motor connections, then found that the wheels would only turn about 1 revolution and then stop each time i connected the loco to the track (clip leads to track).
Huh?
the motor ran fine, with the decoder removed and connected to the track thru a full-wave bridge. PowerCab reported 0.51 A with the wheels stopped. The decoder is a TCS T1 rated at a 1A. It ran fine after the reset and reassembled.
it had momentum programmed. it's an old brass 0-6-0 with an open frame vertically mounted KTM motor
what decoder parameters could possibly cause this behavior?
tanks
greg - Philadelphia & Reading / Reading
Did it do the same regardless of throttle position? If it only stopped at low speed, it could be the kick start settings, just not giving it enough torque to get past the stickiest part of the mechanism, which is why it always stopped in the same place. Or the BEMF parameters are off, not able to overcome a sticking point in the mechanism.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
when it only turned one wheel revolution, i simply connected it to the track w/o changing the throttle. I tried only one setting.
i also forced it to stop at a different position and from then on, it seems to stop around that position.
it ran for about 3/4 sec. it didn't seem to have any problems starting the motor turning and it seemed to run evenly.
i don't understand why if there's some binding in the mechanism, why it could start but not get past it while running. If it is due to some binding, possibly at every 90 deg, it seems the parameters before reset caused it to stop driving the motor at some lower measurable value that became a higher value after reset
could this be some time setting?
can someone help me understand the TCS T1 back emf options decribed in their literature under "Back EMF and Rule 17 Dimming Options".
what does "button control of BEMF" mean?
i wondering if somehow some CVs got unintentionally reprogrammed to cause this problem. And i'm wondering what behavior these CVs are intended to control.
edit: i found the the TCS Comprehensive Programming Guide but still see no explanation for the behavior I see.
Button control of BEMF means it assigns a function key to turning BEMF on and off.
A complete reset should have removed any odd settings. You can try completely disabling BEMF to see if it makes any difference, the default setting is BEMF enabled at low speeds and it cuts out at higher speed steps as set by the controlling CV.
Most of the ones I've installed have exhibited erratic operation for the first few feet of running after a fresh install, while the self-adjusting BEMF figures out the loco. After that, they've all run smoothly. But I haven't had any do what you describe. The one turn of the wheels is what makes me think there's at least partly a mechanical issue, as the decoder has no setting for the gear ratio, so it has no idea how many motor turns it takes to make the drive wheels turn exactly once.
When it stops, will it go if nudged, or do you have to remove power from the decoder? If it just sits there indefinitely, try checking the power at the track inputs and make sure the decoder is getting power. Check the voltage on the orange and grey and see if the motor is getting nay power.
thanks for responding
if it wasn't clear earlier, the reset corrected the problem and the loco has been running nicely. I am curious to understanding what CV settings could possibly cause this behavior. I think it would help me better unstand the capabilties of the decoder.
when is did stop, i tried pushing the motor but it remained stopped until i disconnected from the track and re-connected.
As a result of re-reading the T1 datasheet, I programmed my decoders to dim the headlights.