I’m not overly savvy with decoder, at least not like I probably should be this day and age but I was wondering if anyone else has this issue with any of their units running with a dual mode decoder. I have two Atlas GP38’s that I have consisted back to back, anyway what happens is when I power up my track the two units are out of sync working against each other. I then remove the second rear unit from the consist, adjust the direction and then re-add the unit back to the consist. While it’s not overly serious it is a bit cumbersome to have to setup the consist each time I power up the layout. Would this be an issue with the decoder itself or would it be something to do with my Digitrax system? I’m currently using a Digitrax Zephyr Xtra system.
Also, any advice on speed matching these two units? I spent about 5 hours yesterday in DecoderPro and have got them close but not perfect. Should I be concerned with damaging the motor or drivetrain parts if the units aren’t perfectly speed matched? The units are not spinning wheels or anything but when I run the two separate they run great at certain speeds while others one seems to be going a little bit faster than the other. I was hoping that since both are Atlas and are very similar units they would run well together out of the box. The only difference is that they were produced a year or two apart but I didn’t think that would matter.
Thanks and stay safe out on those 1/87 scale rails!
I had that problem (working against each other) with some Atlas units some time back. I believe what I did was to disable the ability of the decoder to work with analog (DC). Once I had them on DCC only the issue was resolved.
Concerning speed matching, are you using speed tables or just the start, mid, and max voltages? I don’t remember if all the dual modes allow the use of speed tables. I did use the speed tables for a number of friend’s dual mode equipped engines. He wanted the top speed set at 60 smph. This top speed is not relevant to anything, except that I noticed that the speed curve was very shallow. For example, other Atlas locos with non-Atlas decoders might have speed step one set at 8 and speed step 28 set at 150, while the dual mode might have the range between 8 and 90. To me, values like the latter would be analogous to operating with only a portion of the rheostat on a DV power pack.
Anyway, to answer your question, no they don’t have to be perfect. And you won’t be able to get them perfect. As long as there is not a lot of spinning of the wheels as the units go by you should be good.
John, its a good practise to unMU them after your done and dispatching them from the Zephyr and then shut it down. Sure its a pain in the rear having to MU them again BUT realistically it only takes 20 seconds or so to do it. That avoids any funky issues that tend to pop up from time to time and also prevents any runaway locos when you first turn on the layout.
Thank you for the replies. Both are currently set to DCC only. I’m trying to use speed tables to bring one closer to the other one. I’m assuming the dual mode decoders allow the use of speed tables because the option to utilize them is available in DecoderPro. I’m back at again to try and get them closer but at the same time I’m about to pull my hair out! I didn’t think it would be this difficult or that it would take so much time! I can’t imagine trying to do this tedious task without a computer interface! Maybe I’ll just revert back to “close enough” like I had it last night…
There are two methods of doing this. The first involves picking a loco that you want to be the standard to which everything else is set. You then adjust the CVs of the second loco and try to approximate the speed of the first at various speed steps. I tried this method and you are correct. It does become tedious even if you are using decoderpro. My opinion is that the problem with this method is that you really don’t know what speed the first loco is going at any particular speed step, unless you arm yourself with a stopwatch and have a defined length of your railroad marked off so that you can calculate scale miles per hour. You would then have to do this calculation for every speed step where you would want to set a CV.
Once that was done, then you’d introduce the second loco. So how would you do the speed comparison? Would you watch the second loco follow the first and visually try to determine if the speeds were the same? You could try this, but if your railroad is like most everyone else’s and has ups and downs, the speed of each loco will be affected by the grades, going faster downhill and slower uphill. The other option would be to time the second loco as it goes through your measured mile and do the calculations. Very tedious.
The second, more expensive option is to get yourself a speedometer. As each loco goes across the speedometer you get a readout of what that loco’s speed is for every speed step. I’ve done a bunch of locos for a friend. He wanted his top speed set at 60 smph. So what I did was set the top speed (CV28) at 60. Then I set a straight line between step one and step 28. You’ll notice on the decoderpro speed table that there are littl
If you run them together all the time, you could set CV19 on the programming track. Set your leader to the 2-digit address desired, then set the unit going the other way to 128+the 2-digit address. Decoder Pro can handle this for you.
The 4 engines in this shot are set up thusly, even numbers one way, odd the other.
I’m pretty sure the Atlas 342 decoders do not support CV 5 & 6, so messing around with the full speed tables is required. Close is good enough for the speed matching. They also don’t seem to support CV21 & 22, so you still need to dial up each unit to turn the head light on.
I have a number of these decoders, and am in the process of replacing them with TCS A4X, so that the engines run better, lighting effects are better, and functions respond to a consist address.