I recently updated my Atlas DCC system to a Lenz. I have a few inexpensive MRC F units that came DCC equipped. I bought them at Trainworld for not much more than the cost of a low end decoder. When I ran then on my Atlas system, I noticed that the headlight blinked on and off as the train moved and I chalked that up to “you get what you pay for”. With my Lenz system, instead of a dial on the throttle, you use a push button to step the speed up and down the throttle displays a number that corresponds to the speed of the loco. What I discovered was that when the speed is set to an even number, the headlight remains on, and when I step the speed up or down to an odd number, the headlight shuts off. In all the reading I have done on DCC I have never read about a connection between the engine speed and the headlight. This happened with the Atlas throttle as well but because there was no display on the Atlas throttle, I never made the association. Is this just a quirk with the decoder used in these locos or is there another explaination? I haven’t seen this happen with any of my other locos.
Real strange. I know nothing about DCC, but computers and digital logic is an area where I have a little epxerience. When the loco is off, somewhere there’s a data register with all zeros in it, ok, fine, the headlight is off too.
Any binary representation of an even decimal number, however, ends in zero, and here, your decoder reverses its abberant behavior.
It turns off when the last bit is holding a one, the binary representation of an odd decimal number, not when the last digit is a zero, as would be expected.
Curious.
A solution will have to wait for someone with DCC experience, but I share your head-scratching reaction.
What you’re seeing is a quirk that results when the throttle is configured to control a 28 speed-step decoder (which is the default setting for most recent Lenz throttles), but the decoder is actually only operating in 14 speed-step mode. A number of the “economy” DCC decoders that were released early in the DCC era were only set up to use 14 speed steps. Early MRC decoders only supported 14 speed steps.
The solution is to set the throttle to 14 speed steps when using these locomotives. One place where this is described is on pages 17-18 of the Lenz LH90 manual You can find a copy of it at http://www.lenz.com/manuals/xpressnet/lh90.pdf.
Given the improvements in low-end decoders since the MRC ones came out, a lot of people have opted in recent years to replace their old MRC decoders with ones from Digitra
Maybe your decoder headlight function is set to act as a Mars light.
Good answer, fmilhaupt. Sounds logical. Obviously there was a reason these were so cheap, even for Trainworld. I had no illusions about their quality when I bought these engines. I figured they would be a cheap way to build my diesel fleet figuring to replace them with high end models as funds allow. I discovered something else about them. The shells are almost identical down to the rivet as some very old Athearn BB F units I have laying around. They also look very similar to the pictures of BLIs new F units although of course the BLI has better add on detail. It wouldn’t surprise me to learn they are all working with Athearn’s shell.
MRC decoders have always been the worst on the market. I purchased one of those “DCC Equipped” locomotives when MRC first came out with them and the decoder that was in it was bad. At the same time I purchased a 5-pack of MRC decoders because they were on sale – 3 out of 5 of them were bad. So out of 6 MRC decoders only 2 were good.
A member of our HO scale club kept buying MRC sound decoders because they “were cheap” – over a one-year period every one of them had to be replaced because they burned out.
I will never, ever touch another MRC decoder.