Bachmann 21 pin decoder CV help

[AlanVSparks]

I am trying to tune a Bachmann 21 decoder (36-554) with back EMF.

 

I have fitted it to a BM 47 but CV3 and CV4 are not responding as I would expect. I have put in CV3 the Max (64) for acceleration but the spoon shoots off like a rocket and on slow down there is little speed reduction until the final few speed steps when it suddenly stops.

 

I have played with max speed and EMF.

 

Has anyone worked out a good set of CVs I can try to give a good speed response? This decoder does have limitations I know but when consisting with other BM(sound) locos it would be good to get a close speed match.

 

Thanks

[Lady_Ava_Hay]

I am trying to tune a Bachmann 21 decoder (36-554) with back EMF.

 

I have fitted it to a BM 47 but CV3 and CV4 are not responding as I would expect. I have put in CV3 the Max (64) for acceleration but the spoon shoots off like a rocket and on slow down there is little speed reduction until the final few speed steps when it suddenly stops.

 

I have played with max speed and EMF.

 

Has anyone worked out a good set of CVs I can try to give a good speed response? This decoder does have limitations I know but when consisting with other BM(sound) locos it would be good to get a close speed match.

 

Thanks

 

Remember that CV29 needs to be set to differentiate between the individual CV's 3,4 and 5(?) and the speed table CV's 67-94. If the speed table is corrupt that will cause the problem you have and any amount of changing of other CV's won't have any effect at all.

 

DecoderPro and a SPROG will sort this if you lack a Lokprogrammer.

[Adrian Wintle]

I am trying to tune a Bachmann 21 decoder (36-554) with back EMF.

 

I have fitted it to a BM 47 but CV3 and CV4 are not responding as I would expect. I have put in CV3 the Max (64) for acceleration but the spoon shoots off like a rocket and on slow down there is little speed reduction until the final few speed steps when it suddenly stops.

 

I have played with max speed and EMF.

 

Has anyone worked out a good set of CVs I can try to give a good speed response? This decoder does have limitations I know but when consisting with other BM(sound) locos it would be good to get a close speed match.

 

Thanks

 

The max value for CV3 and CV4 is 63 per the manual. Depending on how they implemented the firmware, 64 may appear as 0, or it may cause the decoder to act unpredictably (see warning in the manual).

 

Adrian

[hoover50008]

There is usefull information to be found in CV29 demystified on page 11.

 

E

[AlanVSparks]

There is usefull information to be found in CV29 demystified on page 11.

 

E

 

 

Thanks for the advice, I will have to look for this page 11 and make a study of CV29.

 

Cheers

Alan