Consisting

[streamliner51]

I would like to use helper locos on my DCC layout. My locos are pricipally BLI plus an Athern EMD pair. I do not want to spend much money so purchased a cheap pair of 'DCC on-board' diesels made by Bachman with 4 fuction decoders. I use an NCE Powercab. Unfortunately the characteristics of these does not match my locos, they need to be step 15+ (out of 28) before they move and then cannot match the speed of my locos. I have tried changing the settings for CVs 2,5 and 6 but this has no effect so presumably the decoders are not sophisticated enough.

Can anybody suggest a solution? I suppose I could purchase some small BLI diesels but I would prefer to spend less money! I do not need locos with sound/smoke so how can I tell if another make would be satisfactory?

[BigDaddy]

streamliner51

I have tried changing the settings for CVs 2,5 and 6 but this has no effect so presumably the decoders are not sophisticated enough.

Starting voltage is a pretty basic DCC function, there ought to be some effect.  Anxious to see what the gurus have to say.

[jjdamnit]

Hello all ,

The Bachmann decoders are extremely limited in their CV functions.

Speed matching to other manufacturers can be difficult to say the least, if not impossible.

The cheapest solution would be to replace the decoders. The Bachmann diesel engines I have all have NMRA 8-pin plugs. 

Replacing the decoders is a relatively simple procedure.

Simply pop off the shell(s) unplug the OEM decoder(s) and replace with the new one(s).

I recommend the Digitrax DH126PS. These are a two function decoder with many CV options and speed tables.

The DH166PS has six functions if you require more function outputs.

I have replaced several of the OEM Bachmann decoders with the DH126PS' and the performance of these engines have vastly improved.

Hope this helps.

 

[MisterBeasley]

I had the opposite problem with a couple of Bachmann Sound Value decoders that wouldn't recognize Vstart.  I lowered Vhigh which lowered all speed settings and got rid of jackrabbit starts.  You may be able to increase Vmid to effectively increase your start voltage.

[streamliner51]

Thanks for the advice, I have just ordered two DH 126PS decoders.

[rrinker]

 I DO with poeple would pay attention to the FULL original message before recommending decoders. With a poowerCab, there will be issues consisting the Digitrax decoders and having them run the same as they do when not in consist. This is because Digitrax has 2 different BEMF settings, one for single running, and one for Advanced Consisting. This normally does not affect Digitrax users because Digitrax doesn;t use Advanced Consisting by default and so the loco runs exactly the same alone or in consist. But NCE does use Advanced Consisting, so to get the loco to run the same alone or in consist, you will have to adjust CV57. The default is usually 5 or 6, out of 0-15, which is a little less than half - FOR SINGLE RUNNING ONLY. If you want the same amount of BEMF in an Advanced Consist, you need to read the current value, and then calculate the decimal value of having 2 hexidecimal digits the same - say it is 5, you want to set it to 55 hex which is 85 decimal. Or if it is 6, you want 66 hex, which is 102 decimal. Basically, take the current value, multiple by 16, and add the current value, to get the new value. Then the loco will operate the same alone or in consist.

 I'm not aware of any others (not TCS, not ESU, not Soundtraxx, NCE's decoders don't have BEMF at all) that do this, just Digitrax. And I think it is just a leftover from an early (false) concept that consisted locos where multiple decoders have BEMF will 'fight' one another. I've run all sorts of locos together with BEMF enabled on all of them and have never had that kind of problem. But I don't use any Digitrax decoders. I also don't match my locos to run in lockstep - as long as one doesn't take off at twice the speed of another, or one doesn't start moving until step 8 and the other moves at step 1, it all evens out when there is a load to pull. Basic adjustment is usually all it takes to get them similar.

                                                --Randy

[shahomy]

i have 3 bachmann locos w/dcc on board, GP40,FT-A, and an F7A. The F7A was DC only when i bought, but just recently plugged a NCE D14SR and it works perfect.

So 2 Bachmann and 1 NCE decoders. I just tested all 3 and they all start moving at step 2 (of 126)...i haven`t changed any CV`s. I have the procab NCE.

Anyway, thats what mine are doing...

[streamliner51]

But that is my problem, Bachman’s require 15+/28 whereas others only need less than 5/28 so what happens is that the Bachman’s are being dragged along, the exact opposite of what I need !!

Would it be OK to turn off the BEMF of the Digitrax decoders? rather than calculating the BEMF values, these locos will only be used as helpers.

[jjdamnit]

Hello all,

The Digitrax decoders not only support CV 2, 3, 4, 5 & 6, but also many other CVs that the Bachmann decoders do not, in addition to speed tables.

In my experience the Digitrax decoders also improved the motors performance in the Bachmann locomotives. Perhaps this is due to the BEMF. 

With the Digitrax decoders you can now speed match all of the motive power and, depending on you particular DCC system, simple or advance consist the locomotives for your particular helper needs.

For some suggestions on consisting; also referred to as MUing or Multi Unit, see this link: http://cs.trains.com/mrr/f/744/t/265412.aspx

Hope this helps

[rrinker]

 Yeah, don't disable BEMF, out of the package it shouldn;t need step 14 or better of 28 to start moving - if it does, check the locos themselves for binds in the mechanism because that isn't normal, not with a BEMF decoder.

 Adjust the performance for a reasonable match with the others, try using just the 3 steps, CV2 for start, CV6 for mid throttle, and CV5 for top speed. Once it's good, match the BEMF CV values like I mentioned and the loco will run identically in consist, so now when you consist it with the others, it should still run close (if it did when they were individual). It's just one extra quick step, it's just one most people seem to forget about or don't realize exists, because ONLy Digitrax decoders have it, and Digitrax users using these decoders don't have to worry about it because Digitrax doesn't do consisting the same way as NCE. Which again makes me wonder why it's even in there. I'd love to ask that of AJ (the designer of Digitrax equipment).

                                        --Randy

 

[streamliner51]

It seems th DCC gods are against me. When I opened one the models there is a circuit board (which presumably includes Bachmann's decoder) but there is no NRMA DCC socket so the decoder cannot be changed!! How can I avoid repeating this situation? The model numbers; 60716 and 60818 are described as 'DCC Onboard', I have another Bachmann model thus descibed which does have a DCC socket fitted decoder-I have fitted one of the Digitrax decoders and it's performance is much improved becoming quieter and smoother.

[streamliner51]

Since my last post I have found that NCE make a decoder specifically for Bachmann locos, Part No 524139 so I will try it.