I have no DC on my layout, only DCC. Is it necessary or recommended that I disable the DC function on my decoders?
How is this done?
73
Bruce in the Peg
I turn the DC function off on all my decoders. It is part of CV29.
Here is a handy calculator table for CV29.
http://www.2mm.org.uk/articles/cv29%20calculator.htm
Rich
Alton Junction
Blind Bruce I have no DC on my layout, only DCC. Is it necessary or recommended that I disable the DC function on my decoders?
I would recommend disabling the DC (analog) function in your decoders. Here's a reason why: If you have a short circuit condition on your layout with DC (analog) enabled and the protection system either doesn't pick it up soon enough or fails altogether, the decoder may interpret this signal as "GO" and all the locos that are on the track will run at full throttle in whatever direction they're facing and the only way to stop it is to kill power altogether. Even if you're quick to react, the damage to your trains and layout will already be done. Disabling DC (analog) mode is insurance against this "runaway train" syndrome.
Blind Bruce How is this done?
This is usually done by changing a value in CV29. The value depends on what brand/manufacturer decoder you're using, consult your operators manual or go to the manufacturer's website and see what CV29 needs to be set to disable the DC (analog) mode. If you disable this, remember that if you take the loco to a DC layout to run, you'll need to enable this feature. Otherwise, it'll just sit there and look cool.....
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PennCentral99 This is usually done by changing a value in CV29. The value depends on what brand/manufacturer decoder you're using, consult your operators manual or go to the manufacturer's website and see what CV29 needs to be set to disable the DC (analog) mode.
This is usually done by changing a value in CV29. The value depends on what brand/manufacturer decoder you're using, consult your operators manual or go to the manufacturer's website and see what CV29 needs to be set to disable the DC (analog) mode.
I'm not sure what you mean here. CV29 is the same for all decoder manufacturers in order to comply with NMRA standards.
richhotrain PennCentral99 This is usually done by changing a value in CV29. The value depends on what brand/manufacturer decoder you're using, consult your operators manual or go to the manufacturer's website and see what CV29 needs to be set to disable the DC (analog) mode. I'm not sure what you mean here. CV29 is the same for all decoder manufacturers in order to comply with NMRA standards. Rich
For a 2 digit address the value in CV29 is usually 6
For a 4 Digit address the value is 38
to turn off the DC conversion in a decoder with 4 Digit address place the value of 34 in CV29
This turns off the DC conversion! This is what is being talked about - If the decoder does not see a DCC signal within a few seconds upon start up the Decoder will assume DC and turn on FULL and the Engines takes off!
BOB H - Clarion, PA
Bob, what I was referring to is PC's reference to "the value depends on what brand/manufacturer decoder you're using". It shouldn't matter what brand or manufacturer. All follow the MNRA standard as toCV29. A value of 34 in CV29 produces the same result whether the decoder is from Digitrax or NCE, for example.
Correct! - My mistake in missing the point you were making!
Thanks!
Subtract 4 (decimal) from the value in CV29 to turn analog conversion off. Every NMRA compatable DCC decoder will work this way.
Martin Myers
I always set CV29 to a value of 34. That sets to decoder to use a long address, forward direction, disable DC operation, and 28/128 speed steps.
richhotrain I'm not sure what you mean here. CV29 is the same for all decoder manufacturers in order to comply with NMRA standards. Rich
What I meant was the value that is programmed into CV29. I use Soundtraxx Tsunami's, there are 32 different values I can program depending on what I'm looking for. You already gave a few examples. A value of 6 is default, 34 would be for extended address, no speed tables, no analog, 28/128 speed steps and normal direction. I use a value of 50 in CV29, the difference is being able to use speed tables.
PennCentral99there are 32 different values I can program depending on what I'm looking for. You already gave a few examples. A value of 6 is default, 34 would be for extended address, no speed tables, no analog, 28/128 speed steps and normal direction. I use a value of 50 in CV29, the difference is being able to use speed tables.
Bruce: You have a NCE system, is that not correct? While it is nice to learn about all the different CV values and how to calculate them, you don't really need to worry about that right now if you don't want to. The system will do that for you
Put your loco on the track. With the handset:
1. press the prog/escape button.
2. first selection that comes up is "program on the main". press enter
3. it will ask you for the address of the loco that you want to program. enter that number and press enter.
4. screen will say 1=address, 2=CV, 3=config. press "3"
5. first screen to appear will ask if you want normal direction. press enter.
6. second screen to appear will ask if you want to use 28 speed steps. press enter
7. third screen to appear will ask if you want DC mode. enter=no, 1=yes. press enter
8. press program/escape key two times to back out of programming.
Done
Blind BruceIs it necessary or recommended that I disable the DC function on my decoders?
I see people recommend this all the time to prevent "runaways" after a short ciruit. Maybe some command stations do not restore power as cleanly as others after a short, or maybe some decoders are more prone to runaways, but I have not disabled DC conversion in any of my locos and I have NEVER had a locomotive runaway on me.