Atlas B40-8 Dual Mode Decoders

[sd80mac]

Hi group, I have some questions regarding the old Lenz dual mode decoders used in older Atlas engines, namely the HO B40-8s/B39-8s. Do these not have any kind of BEMF? I own 5 of them and they all seem to greatly pick up speed going down hills while other engines stay at a constant speed. Is this normal? Is there any way to change it?

On a related note, I've adjusted the speed table in some of my B40s to better run with other models. When I have the B40 and the other engine on separate throttles, they run fine together. However, when I consist them (I use Digitrax at home and NCE at the club I belong to, it happens on both systems), the speed table seems to disappear from the B40 and it reverts to going just as fast as it was before they were consisted. Any ideas?

[railfan4life]

I pulled one up in DecoderPro and couldn't see any functionality for BEMF or similar capability. There are adjustment for consisting. You should check to see what is currently stored in those CVs and if the increase in speed is consistent, you could make some adjustments.

Hope this helps.

[bnsf971]

Those decoders are very basic. I have not been able to find BEMF on them, and have had to load speed tables to get them to play nice with my other decoders.

One of the things I do like about them, is most of them have the capability to use rule 17 lighting by pushing a function button. I remember function 2 being default, but remapping to another function button is easy.

[kentuckysouthernrwy]

I have 4 Atlas B-40 and I have only run 2 together and only on my home NCE layout, the other 2 run singly.. one I have is terribly buzzy, the other 3, not so much.

[bnsf971]

Feb 25, 2014 15:43:11 GMT -8 kentuckysouthernrwy said:

I have 4 Atlas B-40 and I have only run 2 together and only on my home NCE layout, the other 2 run singly.. one I have is terribly buzzy, the other 3, not so much.

Some of the newer dual mode decoders (the ones with 4 functions) have a "silent control" setting. The 2 function decoders do not. FWIW, "silent" is subjective.