TCS Z2 Decoder run-away as soon as it's on the track


T

TheZeke

New Member
Halp! :)

I just installed a TCS 1296 Z2 decoder into an N Scale - SW9/1200 LifeLike locomotive. Pretty sure I did it all correctly except I have *not* wired up any LED yet. That might be important here, I'm not sure. The leads for the LEDs are not connected.

When I put the locomotive on a DCC powered and clean track it starts going full speed (forward) immediately. I put it on a wheel cleaner and let it go full speed while I tried turning CV29 off thinking it was set to use DC power. When setting CV29 to 0 (or 40 if I use the sum of the values for the options I want) it stops going nuts. I'm assuming it's loco address #3 at first so that's what I'm using although it doesn't say so in the instruction sheet. After it stops going nuts I it doesn't respond to the throttle whatsoever. Also if I remove it from the track and put it back on it starts going nuts (run-away) again.

Does anyone have any idea what this could be? I didn't think a motor/body short would do this since that'd either trigger the short protection on the NCE PowerCab and reboot it or cause the motor to buzz (DCC->DC hum).

Any ideas on what I should try are appreciated. Thanks for reading!
 
You need to set CV29 to a value of 34. It is probably set at 38 automatically, even with a reset. 38 means the decoder will sense both DC and DCC current, but it can run away with powering-up surges in the rails because it thinks it's getting full DC voltage. The value of 34 turns off the DC capability and it will only act if it gets DCC signals.
 
Common practice with a newly installed decoder is to put the loco on the 'programming' track before the main powered track. Then check by setting and reading CVs.
 
I had a similar problem with a TCS decoder...however, my result was much more dramatic.
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