How do I Speed match a Bachmann Spectrum N Scale F7 A&B Units ??

Model Railroader Electronics and DCC
1

Can someone help me speed match my Bachmann Spectrum F7 A/B units?

The A unit goes much faster then the B and I can’t seem to get how to achieve an even speed for both on my Zephyr. It has become a bit frustrating as I am new at this stuff and would appreciate any help.

Thanks

Art

2

Which decoders do you have installed in these units?

Some decoders (Like Bachmann) dont have speed tables and cant be speed matched. If you have any quality decoders (Digitrax, NCE and the like) then you absolutely make them run very nice together.

David B

3

I know I got my train shop to put in quality decoders in both units, I want to say they were either digitrax or NCE

4

Ok then, if that is the case, this is what I would do.

  1. Take one of the 2 units and place it on the layout.

  2. Adjust CV 5 until the top end it at the speed you want.

  3. Adjust CV 2 (and set the throttle to speed step 1) so it creeps at speed step one.

  4. Place the other loco on the track with the A unit ( an oval of track works best).

  5. With the other loco as the top unit in a consist (read your manual on how to consist), consist the B unit and the A unit.

  6. Adjust CV5 while they are consisted (through OPS mode programming…again read the manual) until they have the same top speed.

  7. Un-consist them and adjust CV 2 as before so it creeps at speed step one.

Congrats, they are now speed matched.

David B

5

David,

almost have them at the same speed, but the A unit stops before the B unit does.

How do get them to stop at the same time?

6

Once you’ve got the running speeds matched up pretty well, you can use CV 3 and 4 to adjust the momentum settings to fine tune the starting and stopping of one engine to match the other. Increase the value in CV 4 for unit A a little and try it again, it will cause the A unit to ‘coast’ a little longer when coming to a stop.

It’s always a bit of trial-and-error with speed matching, but if you take your time you can usually work it out so the engines run together very well.

BTW you don’t have to use speed tables to speed-match two engines, usually using CV 2-5-6 for speed and CV 3-4 for momentum are all you need to adjust. I only use speed tables on engines with Soundtraxx decoders, since they don’t use the speed CV’s (2,5,6) like most decoders.

7

CV 2,5 and 6 make a 3-point speed table (It actually sets an internal 28-step table in the loco). Bachmann decoders dont have 5 or 6, hence, no speed table. Lets try to keep our terminology clear as not to confuse newcommers to DCC.

In terms of getting them to stop at the same time, I would still work with CV 2 (start voltage). I would not, however, use CV 4 to adjust stopping time. CVs 3 and 4 dictate momentum, it is not a setting that tells the decoder to stop at a certain voltage. Speed matching is done with CVs 3 and 4 set to 0. When they are speed matched, then you can use CVs 3 and 4 to adjust ‘mass’.

David B