Can too much load be placed on a TMCC speed control module ?

From what you've said, my guess is, it's signal issue. Flickering lights are a symptom of loss of the ground component of the radio signal, commonly called "ground plane". Put your hand over the engine. Does it go?

Just because one engine works on your layout, doesn't mean all will. They are all different. There are some things you can do to the engine, and other things you can do the the layout, that MAY correct this.

6 dash number would help!

It could be signal related.  We are in the process of building the layout (fairly large, 35 x 35 ft. around the walls, multiple levels with an out and back 20 ft. peninsula and will have many of the issues Elliot has chronicled in his build-out), still in the bench work phase but the owner has temporarily laid some track with only one power and one ground wire in place over at least 100 feet of track between where the wire connects to the track and where the engine stalls.  I did however try jumping the track feeds to a point close to where the engine stalls with no joy.  I also tried the hand over the engine trick but it did not help.  We didn't try moving the command base, which for now is located in the ceiling resting on a steel beam and could be blocked from communicating.....I don't have the 6 digit number as the engine is not mine but I will be there today so will try to get it.

But, putting aside this specific issue, is it possible to overload a speed control board?  The owner is concerned the engine might be crapping out.

Thanks for the input!

Dave

It's a bit difficult to offer an intelligent answer without knowing what electronics package is being used.

I have found that as some engines heat up they lose signal. I have a DD 35 that runs fine for 20 minutes pulling 20 cars, then it gets warm and the headlight starts to flicker and would not run. My VL Big boy has started to do the same thing now. It's going to Alex for repair.

Jim D.

Trying to get better intel now, but not sure the owner is on-line.  I will, however, be at his house after noon so I can get the info then and post it tomorrow.

Thanks!

Dave

Milwaukee Road Dave posted:

Trying to get better intel now, but not sure the owner is on-line.  I will, however, be at his house after noon so I can get the info then and post it tomorrow.

Thanks!

Dave

As Marty repeatedly says the item number would help a lot. Pictures?

What types of cars? Atlas scale 25K tank cars weigh a lot, the Lionel 30K are like feathers. Axles oiled?

Is it pulling the consist downhill? Or are cars still going uphill?

As has been mentioned, specific assistance can't be provided without an item number.

But according to your description, if this is indeed TMCC and not Legacy, then you're right... it could be a DCDS problem.

In the TMCC architecture, the classification lights are controlled by the DCDS, and if they flash or turn-off prior to a loco stalling, that's a symptom of overloading or another DCDS problem. This is NOT the same as a headlight flickering, which is usually a signal issue.

If I remember right, those DCDS boards were rated about 10 amps, assuming they had proper heat sinking. Unfortunately, the bridge rectifier on those boards is not protected, and at extreme loads, they can overheat. The problem was solved in later years by going to a "tethered" bridge that could be screwed-down to a frame to provide for heat sinking.

TRW

Thanks TRW, that is what I was looking for, some indication that this might be a board issue.  Definitely blinking markers, not blinking headlight.  And the engine will move the train some (20 - 30 feet) before stalling and the markers blink. 

I will get more specific info on the loco later.   Te 50 cars are mostly Atlas cars (reefers, cabooses, box cars) and it is a heavy train, it takes some effort by hand to get it rolling even going down grade (which as indicated in the original post is the direction of movement right now).  In addition to the weight, the cars are mostly moving in what is essentially a figure 8 (folded peninsula) so most of the cars are moving through two complete circles of track (O-104 for the most part) adding additional pressure.  The engine is a Y-6 or Y-3 purchased fairly recently and is definitely not Legacy.

It's called bucking.  Pre-Legacy steam (including those from most other brands) use self-locking worm gears.  That means the weight of the train cannot "push" the loco when the motor is not turning.  Without speed control, sometimes you would see noticeable lurching or a slinky effect as the loco goes downgrade with a consist behind it.  Ugly and unrealistic, but not a major problem.

Introduce TMCC / Odyssey, and now the speed control is trying to keep the loco at a constant speed.  The problem is, the load on the motor varies as the worm gear picks up each tooth with all of the train weight trying to push the loco down the grade.  No easy way to solve this... maybe a lower track voltage so that the torque gain commanded by the speed control circuit isn't as great?

The real solution is a Legacy loco with back-drivable gears  (i.e., wheels can turn the motor.)  As to why the older loco doesn't buck going down the grade, my guess is that it has a different gearbox, or perhaps tighter mesh between the worm and worm wheel.  You might also check the drive rods on the problem loco for binding.  My $.02.

We think the problem is solved, Ted S.'s comment about downhill affects got us thinking about our grades.  But first, some house cleaning.  The engine in question is a lot older than I thought.  It is a JLC Y6b from 2003 with Odyssey speed control, model number 6-28085.

With some additional testing we noted this engine under load seemed to stop at nearly the same location every time while two other Lionel engines of the same wheel arrangement (vintage unknown) made it through.  This location happens to be where we needed to change (and fairly abruptly) the downhill grade (0.7%) to flat, then upgrade and back downgrade (almost 1.0% both up and down) to overcome a grade separation issue.  And all this transition was occurring in about 25 feet while also negotiating another curve.  Based on Ted S.'s comment, we decided to flatten out the grade through the grade separation and curve to see what would happen and voila!, the engine under load made it through.   We basically just released all the screws holding the risers and let the road bed find its own level, there is still a grade but it is under 0.5%.  Our grade separation is an issue again (by about 1/2"), but we think we have a solution while maintaining the new grades.  And the owner (actually all 3 of us) are a lot happier with how this section now looks, more subtle and less abrupt.

Thanks to all for your assistance!

Dave