Having received an ABBA set of Walthers Great Northern F7s for Christmas last year (my wife always knows what to get me
), earlier this year I set about installing LM-2S modules in them. Initially I thought all was good as they seemed to run well. But quickly I discovered that as they ran, they kind of sputtered. They would occasionally, randomly, stall briefly for a fraction of a second. They would stop motion and the sound would cut out, then quickly recover motion and eventually reset the sound. I thought at first that it might be a problem with the pickup system (though they have 8-wheel pickup) which didn't please me, but recalled that per Walthers recommendation I ran them each for an hour to break them in, on DC and prior to the LM installation, and they ran perfectly.
I made sure both the wheels and track were clean and yet they still sputter. Not all at once mind you, but individually, at different times and places. There was a time when I thought it might be related to unpowered frogs (at our club layout) but the sputtering was so random and inconsistant I had to rule that out as well.
So, last weekend I took them to my DCC installer guy (whom I go to for difficult installs like brass steamers) and we investigated pretty much everything we could think of. He went through one of the B units from top to bottom, cleaning, adjusting, aligning, you name it. Still it sputtered. Finally, and based on my responding to his question that they ran perfectly on DC, he removed the LM-2S and plugged in a Digitrax DH-123. The engine ran perfectly with no sputtering.
So now we're curious. The only theory we can come up with is that perhaps, for some reason, the LM-2S doesn't get along well plugged into the factory board (where the 9-pin connector originates from). He's thinking perhaps there is some sort of weird feedback situation going on that affects the LM but not the DH decoder.
So my question to you all is, has anyone here experienced this in any of your installs where you plugged an LM into a factory board?
In the mean time, of course, I am having him remove the factory board and hard-wiring a 9-pin in the test B unit. I expect to hear from him soon on the success or failure of that solution and will report back when I do.
Here are some pictures of how I installed the LM originally so you can get an idea of what all is in this thing. The pics are of the lead A unit but all the units are essentially the same (save for the lack of lights in the Bs).
The unit fresh out of the box with the shell removed:
(the factory board in question is the one in the middle, mounted above the motor. The board at the rear of the unit is just the 9-pin version of the jumper connector that allows DC operation)
With the speaker enclosure removed and the components gathered:
Feeding the speaker wires through the enclosure access and soldered to the speaker:
Speaker enclosure reassembled:
Enclosure reattached to chassis, 9-pin connector rerouted, and LM plugged in and secured:
--Michael
