P2K E-7 direction of travel

[gmpullman]

Well, I made my first oops when installing a DH-121 decoder in a Lifelike E-7.
Without refering to several instalation directions, I assumed the motor leads were red=pos and black=neg but no... Murphy says they're opposite on the P2K E-7... So everything runs backwards. I didn't want to cut & solder the wires again (didn't leave all that much extra wire for mistakes!)
I see that there's a way to change the NDOT: normal direction of travel on these decoders. could someone give me a quick rundown of just how to do that using a DT-400 throttle?
Thanks... this forum has been a life-saver!
Ed

[rrinker]

You have a DT400 so I assume you have a Digitrax system. If you have a Super Chief you can read CV's, if a Super Empire Builder, you can not. The reason for this distinction is for figuring out what to program. In ANY case, you need to add a 1 to whatever value is in CV29. The existing value is going to vary depending on several other factors. 14/28/128 speed steps, DC conversion, use of speed tables, and the direction of travel are all controlled by CV29.
Assuming 128 speed steps, no speed table, 4 digit addressing, and the default of analog conversion ON, CV 29 right now is probably 38. TO switch the direction of travel, add 1, so you would program CV29 with 39.
With a Chief or Zephyr, you just read the current value of CV29, add 1, and program that new value back in.

--Randy

[gmpullman]

Thanks, Randy
I just put the errant E-7 back on the programming track and dialed in CV29... I think it was set to 36 and I just hit the + button to bump it up to 37... hit enter; exit. The display said OK (or good... whatever) and I was rolling in the proper direction!
I'll get the hang of these CVs yet!!! Now tell me why Lifelike chose red wire for the motor negative???
Ed

[rrinker]

Well, you do have the ORANGE wire connected to the red, right? Orange is the decoder motor drive + lead.
I haven't done any E's and PA's yet. I know my GP-7s run 'backwards' but that's because some road ran them short hood forward and some long hood forward, and LL set them up to run short hood forward by default. I even had to pop out the little crew figures and fli them around.

--Randy