TMCC Lash-up Problem

You'll make Rich Melvin's day if you change "lash-up" to "MU" (multiple-unit) which is authentic real-railroad terminology. Trying to class-up the forum!

Sorry I'm not an electronic control expert but I'm sure someone else can answer your question.

I considered using "MU" but the TMCC instructions refer to it as a lash-up so I stayed with it.

George

OK, then, here's a class response to the gentleman's post:

George,

I'm presuming these units have "EOB" (for "Engineer on Board") speed control. Check the operating instructions and you will see that in addition to setting momentum, there is a way to adjust the parameters of the EOB settings. First, make sure all the units are set to the same speed step setting, either 32 or 128. Next, you will see that there are ways to adjust the settings called "pre-pulse" and "background pulse." These affect how quickly EOB provides power to the motor. Setting or re-setting them may allow you to tweak the odd-man B unit to perform in sync with the others.

A caveat: Some years ago, Bill Serratelli at Atlas told me that the pre- and background- pulse values had changed from what was published in the instructions. Now that was in a discussion of a six-axle unit, but you might contact Bill if this doesn't work. If all else fails, it might be a good idea to contact Bill in any event.

I don't think momentum setting does much with EOB engines, except maybe in commanded braking situations. Checking the speed steps and the pre- and background- pulse are likely you best bets.

Good luck,

RM

You can turn the speed control off and on, which from the way it appears to be operating, may be the case.  The off mode is used when in a consist with a non-EOB locomotive.

32 speed step mode

ENG+##+DIR+AUX1+AUX1+AUX1+1

(The horn will sound after the 3rd Aux1 and after 1.)

128 speed step mode

ENG+##+DIR+AUX1+AUX1+AUX1+2

(The horn will sound after the 3rd Aux1 and after 2.)

Cruise control Off.

ENG+##+DIR+AUX1+AUX1+AUX1+3

(The horn will sound after the 3rd Aux1 and after 3.)

On occassion the tach strip may have come loose from the flywheel, or even the tach strip reader from it's motor mounting, usually applied with CA adhesive. Atlas units usually had a pretty nice tach strip flywheel and a better quality mount compared to TAS  EOB upgrades. IMO.

Foggy head says the difference on Background Pulse was 01 to 20 changed to 01 to 99 later.  If the unit won't accept a number larger than 20 it's probably an early issue EOB.  I could be wrong and often.  Mike CT

Thanks, Mike and Rich.  The EOB setting was the problem.  The 2nd B unit was set at 32 while the other two units were at 128.

The MU is running like a charm now.

George