I have a problem with my ho scale Kato SD80macs that are equiped with NCE DASR decoders. The problem is that when they are running in reverse they sometimes stall, but a little change in the throttle and they locomotives will resume speed. This is what I have done to trouble shoot. - It happens in both SD80macs I own - It is not the NCE Pro-Cab because I used two different Pro-Cabs out at my club and got the same result. -It is not the NCE System as the problem occurred on both the club layout, and on the club test track, which is totally independent from the layout. Two totally separate systems. - It is not the wheels of the locomotive as the wheels were cleaned. This has me stumped, as it only happens in reverse. It is as if the system has temporarily lost its signal an by adjusting the throttle it picks up the signal again. Has anyone else had this problem? If so what did you do to correct it? Does anyone know of a similar issue with NCE DASR decoders. Any help would be appreciated. I don't want to have to pull out and replace the decoders if a simple CV fix will take care of my problem. Thanks
It really doesn't sound like a decoder problem to me. It sounds like something is binding when you run in reverse. All a decoder does is change polarity/pulses when you change directions. Does the NCE DASR decoder have back emf? If so, you might want to make some adjustments to overcome the binding. Sorry, I can't be of anymore help. David
To try and pin the problem down some more, is it possible to temporarily swap the wires to the motor in one unit? Don't change any decoder settings, just select Rev to go Fwd and v-v when running. If having done this the problem still occurs running loco backwards, it would indicate a loco problem. Else if the problem now occurs going loco forward instead, it would point to the decoder having an issue.
I may have to do something with the motor leads. It is not physically possible to swap the wires as on this model the leads are wire clips that come up off the motor and are soldered on to the DASR. But that is a good thought, and I may have to check that out. It would entail shortening the clips off the motor and and running wire leads to the alternate place on the decoder. I sent my question to NCE as well. I hope to hear from them. Maybe it could be and adjustment on the time-out packet CV. I am hopeing that is the case as I don't want to ruin an otherwise good decoder installation if I don' need to. I am leaning towards ruling out a locomotive problem. But you never know. It seems unlikely that both locomotives would do it, one to more of a degree than the others. But then again it could be a design flaw of the Kato 80mac. If it was a Bachman yeah I could see it, but Kato has such good mechanisms.
This is a long shot (and may show more about my ignorance than anything else ). Does this decoder have separate speed tables for forward and reverse? If so, is one 'slot' in the reverse table set to 0?
Mike, I have found that sometimes every shot in DCC is a long shot. I guess when all else fails read the manual. I am going to look into this.
Well I think I have come upon the problem. Some other people had this problem, one guy with overland motors, and it turns out to be the decoder. NCE got some bad components from a supplier. This component will act up on some locomotives which have a motor that has a high impedence. It will work fine on other locomotives. So, I have been told to send the decoders back to NCE along with a note and they will replace them.
