I just picked up an Atlas C630 with a decoder already installed. Im using an NCE power cab. This loco buzzes until speed step 11 before it quits buzzing starts moving. Ive tried playing around with momentum and this hasnt helped. Any ideas guys?
Try using 128 speed steps. This might help you out. You can easily convert 28 speed steps to 128 speed steps using your NCE Power Cab. I am using a radio controlled NCE Power Pro with three power districts. All my locomotives run using 128 speed steps. Have fun with it. Shades
The Atlas C630 should start moving at step 1 with CV2 set to (0). If you have to adjust CV2 up to get the loco to start moving than something is wrong with the loco.
The decoder is a factory install. I bought it marked as used at the train store from an estate but I believe it is new as the details are still in a sealed bag and it is immaculately clean.
No, not really. There are some locos that need some extra voltage to get moving from a stop. Either they don't have flywheels, have an older motor, etc. But that's what CV2 is for: to kick start the loco.
I own 2 Atlas C630s and 4 C628, they all start at step #1 with CV2 at (0). I would remove the body to see if the motor turns freely, could be that the loco sat around for a while. Remove any excess grease and lube the loco. You might also want to reset the decoder?
The buzzing is caused by the relative low frequency PWM drive of the decoder. The older decoder design that Atlas used for many years in their decoder equipped locos would make the locos produce an audible buzz. Atlas has switched to a newer design that uses a higher frequency that is less audible. Do your locos have factory installed decoders? If not, what decoders do they have? Have you adjusted any motor control CV's other than CV2? What speed step setting are you using? It is not at all unusual for a locomotive to not start moving at speed step 1. Speed step 1 when using 128 speed steps works out to around 0.1 volts (a little more or a little less, depending on track voltage). I'm fairly confident that I don't have any locos that will start moving at 0.1 volts. When using 28 speed steps step 1 is closer to 0.5 volts, so a loco is more likely to move at step 1 when using 28 speed steps. There are several things that can affect step 1 output other than adjusting CV2. If the decoder has bemf compensation and it is on and configured correctly, then it will automatically increase the output until the loco starts moving. There are also other options, depending on decoder brand, things like kick start, dither, torque compensation. Also, if the decoder is setup to use the 28 step speed table, step 1 in that table takes the place of CV2. However, when no other motor control options enabled, these locos will not start moving at speed step 1 of 128 when CV2 is set to 0.
First off, NEVER EVER assume a loco is going to run even straight from the factory. I've purchased plenty of bum locos in the past. Hmmm... I would take the shell off the loco to see exactly what is going wrong. Regardless how old a loco is, they always need a little TLC to get them working properly. Once you've opened one loco you can do it with all of them and that is useful knowledge and experience. Besides if you remove drive sections you can also just test it to see if maybe something was binding and causing issues. Maybe it just sat and the lube went bad. Or it never got enough at the factory to start with. If there is some kind of binding in the mechs sometimes just resetting everything loosens it up. Also, as someone else mentioned; you need to find out what decoder it is anyway. The newer locos are so easy to maintain. They are so beautifully designed. It's a treat to get them opened up and see how they work.
You don't need to take apart an engine to find out what decoder it has, CV8 tells you what manufacture it is (the display is a number, then on a chart that has manufactures and numbers, I downloaded mine at MHR, you find out what the number means). CV7 will tell you what version the decoder is. You might still want to take apart the engine to check out the drive train status, but to just know what decoder you have, you don't need to do this.
Current Digirax and TCS decoders have Bemf compensation and default with it turned on, so most locos with those decoders will start moving at speed step 1 with no further adjustment. The current decoder design that Atlas uses does not have Bemf compensation (it is an NCE decoder); however, they do have "torque compensation". The normal default for those decoders is to have it off; however, it is possible that the ones that Atlas use actually have it turned on for their specific application, though I doubt it. If they have torque compensation turned on from the factory, then they could start moving at speed step 1; otherwise, they will not without adjusting torque compensation or CV2, or using the 28 step speed curve. The older decoder design that Atlas used did not have any additional motor control other than the starting voltage or the 28 step curve. An Atlas loco with one of these decoders from the factory would not start moving on speed step 1 unless CV2 or the 28 step speed table was modified.
I do own one Atlas C628 that does in fact have a NCE decoder and the only thing I have changed is CV3 and CV4. It does start to move very slowly at speed step #1 CV2 (0) and does not make a buzzing sound. I haven't checked to see if TC is on or off, loco runs great so there was never a need to check. I have original Digitrax wired decoders that contained very few options and the Atlas locos they were in still started way below speed step 11.
The NCE decoders do not make the buzzing sound (actually they do, the frequency is just too high for most of us to hear), but the buzzing is normal for the older decoder design (actually a low cost Lenz design). You never did say what speed steps you are using. Speed step 11 when using 128 speed steps would be between 2 and 3 when using 28 speed steps.
