An unanticipated consequence of replacing #10’s decoder was that performance would degrade. It says right on the box that your locomotive needs to work flawlessly before you go installing decoders, but still, a certain amount of back EMF compensation is known to smooth out the occasional foible. The old Zimo decoder worked fantastic right out of the box with #10’s somewhat dodgy mechanical ability (#10 is a good first effort at locomotive scratchbuilding, but I have a long way to go!). The new decoder was not as good with its default settings.
So, I followed the instructions to set the tuning parameters for my particular engine. This starts with setting CV54 to 0 and hitting F1. The engine raced off and the decoder set itself up with what it thought would be best. This resulted in (CV52,53,54,55) = (66,73,39,66).
The behaviour was worse than the default (32,140,48,32). In particular, while it ran smoothly in speed step one, it slowed down to step two. So, I went back to the default and tried jigging CV54 and 55 with little success.
The next day, I looked at the manual, and realized that CV52 amplifies BEMF at slow speeds. So, I returned to the automated settings, and started reducing CV52. When I got it to 25, I was pretty happy with performance in SS 1. Then I started playing with CV54, reducing that ultimately to 24.
I left CV53 alone as it has to do with the BEMF at maximum speed. CV55 didn’t seem to want any modification either. The final settings then are (25,73,24,66).
After I had the engine running about as well as I could (which is admittedly not as good as an off-the-shelf diesel), I followed the instructions to set CV57 and 58 to regulate the chuffing. I also changed almost all the sound functions, although, in reality I only ever use the whistle and bell.
I still haven’t fixed the decoder in place, or covered up the tender. Operation is much better with the tender weighted down. So, I will get the engine all put back together before I go shooting any video.