I've decided to take the big plunge into DCC. I have a Bachmann N Scale N&W J that I installed a Digitrax SDN144PS in. With the factory default settings, it works perfectly. However, when I change the decoder's address, the locomotive jerks forward about half and inch, the sound goes dead and the locomotive will not respond to the throttle. The only way to get it moving again is to restor the factory default settings. What could be the problem?
My system is an MRC Tech 6. I know is a very limited system, but it's just a temporary stand-in until i have enough locomotive equiped to make a more expensive system worth my while.
Any help is appreciated.
Modeling the Pennsylvania Railroad in N Scale.
www.prr-nscale.blogspot.com
Hmm, that's very odd. Changing the address should change nothing else. What value are you setting in CV29? You might be setting it for 14 speed steps.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker Hmm, that's very odd. Changing the address should change nothing else. What value are you setting in CV29? You might be setting it for 14 speed steps. --Randy
I didn't change any of the factory default CV values. Or more accurately, I don't think I did, I'm still a total greenhorn here. The only setting I changed was the address.
If you changed the address from a short (2 digit) to a long (4 digit) address, you must also set CV 29 to a value of 34 to tell the decoder to run on the new, long address.
GP-9_Man11786 rrinker Hmm, that's very odd. Changing the address should change nothing else. What value are you setting in CV29? You might be setting it for 14 speed steps. --Randy I didn't change any of the factory default CV values. Or more accurately, I don't think I did, I'm still a total greenhorn here. The only setting I changed was the address.
The factory default on this decoder is a value of 6 in CV29 (2 for 28/128 speed steps and 4 to allow for DC operation).
Rich
Alton Junction
I changed the address from 3 to 6 since the Tech 6 only suppo Ts six addresses. Could that be the issue?
Does it go back to working ok if you switch it back to 3? What about some other address, like 2 or 4?
It seems to me that the problem is the interaction between the MRC Tech 6 and the Digitrax decoder.
The MRC Tech 6 is not a DCC system. The MRC Tech 6 is a DC power pack with "black box technology", whatever that means. What is purports to do is to "program" some basic CV functions such as CV01-CV06, although it doesn't specifically say that in the manual.
So, the first question in this instance is whether the MRC Tech 6 is working correctly and, assuming that it is, whether the OP is correctly operating the MRC Tech 6. The MRC Tech 6 does permit the operator to change the short address from 3 to 6. If that operation is performed correctly, CV01 should change from 03 to 06 on the decoder. But, in the absence of a DCC system, there is no way to determine the value of CV01. Based upon the information provided by the OP, it seems that the decoder does not correctly interpret the change in the short address.
The other question seems to be why the decoder only works correctly using factory defaults. Since the MRC Tech 6 only has limited capabilities relative to affecting CV values, you would expect that a simple operation, such as changing the short address, should work correctly. The fact that it doesn't suggests that either CV01 has not been changed or that the MRC Tech 6 is still looking for a short address of 3.
Since there is no way to check the value of CV01 in the absence of a DCC system, I would use some trial and error techniques. Reset the decoder to factory default and confirm that the loco runs on short address 3. Then change the short address to 6 and try to run the loco. If it does not respond, then change the short address back to 3 (without a reset to factory deault) and see if it will respond. If not, try changing the short address to either 2 or 4 and see if the loco responds.
If you cannot get the loco to run except on short address 3, you are at an impasse. In that event, if you have access to a DCC system, such as your local hobby shop, you might want to change the short address to 6 with your MRC Tech 6, and then have someone read the value of CV01 to determine how the decoder is affected by the MRC Tech 6.