L-L P2K SD9: Speed matching only works in one direction...[?]

[CSX_road_slug]

I have two early-run HO scale Proto2000 SD units, an SD7 and an SD9, that I'm trying to consist.  Both have NCE D13SRJ decoders.  I'm using DecoderPro on an NCE PHPro system to speed match them.  

The SD9 is the faster of the two units, so I've been adjusting its speed table.  I'll get it slowed to where it runs just a teensy bit faster than the SD7 going forward; then when I change the direction, the SD7 becomes the faster unit.  No matter how much I try to change the SD9's speed, it seems like I always get wheel slip on one of the units anytime I go over speed step #10.

Anybody else ever have this problem?  Is there a workaround?

Thanx

-ken L.

 

[peahrens]

I don't have any NCE decoders I recall but looked at one of the related links:

https://www.google.com/search?q=NCE+D13SRJ+decoders&sourceid=ie7&rls=com.microsoft:en-US:MIE-Address&ie=&oe=&gws_rd=ssl 

It may be that using CV95 forward / reverse trim adjustment on one or both locos will give you the match in both directions.  But I'm not certain if Cv95 can be used as an "overlay" factor atop your basic speed table adjustments.  Maybe someone can elaborate on that.

Another angle, probably secondary or not an issue.  Are the BEMF adjustments the same, or off, so that this won't contribute to issues?

 

[mlehman]

Yeah, CV 95 could definitely cause this. I think you want it set either to 0 or 128 to be off, but check your user info for more on how it's implemented. It doesn't take very much change before the loco will start acting pretty weird unless it's actually need because of some fault of the mechanism.

[CSX_road_slug]

Thanks Mike & Paul, I'll check out the CV95 settings on each unit when I get home from work.

[CSX_road_slug]

Well I had a look at CV95 on both units, it was 0.

But after a little more tweaking I was able to get them both to play nicely with each other.  So I'll go ahead and declare this issue resolved.

Thanks again!

[Robert Frey]

Ken,

I speed match at the AVERAGE mph speed.    Measuer For and Rev at Start, For and Rev at Mid., and For and Rev. at Max.  Then working on both locomotives to get the same avg. speed result mph numbers.   Avg. of Start 1 & 2 have the same mph number.    Avg. of Mid. 1& 2 have the same mph number.    Avg. of Max. 1 & 2 have the same mph number.

PS: This also works for 3 or 4 DCC locomotives running together.   If you really want to get good, put all 4 DCC locomotives together so each avg. high is in the same direction. The change CV29 of each locomotive (if needed) to get the proper high avg. running direction.   

Bob Frey