Atlas GP40 decoder question

[jhock]

I have just fitted a soundtraxx Tsunami decoder to an atlas GP40. The loco came with a built in decoder, across the 2 motor terminals it had a resistor (I think). I have not fitted this to the new sounds decoder but should I have?

 

The loco does not run well at very low speeds (1-4 notches on 128 speed steps), could this be it needs the resistor?

[Prof Klyzlr]

Dear J,

 

Two seperate issues.

 

1- the "thing" accross the motor terminals is most-likely a capacitor used to filter electrical noise, and stop interferrence with nearby TVs, radios, and speakers. For DCC conversions, it is usually reccomended to remove such caps.

 

For specific conversion info, albeit not with a Tsu, check out the TCS website "decoder selector" page.

 

2- low speed performance with TSUs in "out of box" default spec is a commonly noted issue. To achieve smooth consistent low speed running requires some CV tweaking (which, contrary to popular belief, does not _require_ a JMRI rig to perform easily!)

 

Suggest googling "bruce petrucca tsunami dcc slow speed". This should take you to Bruce's "Mr DCC" site, with a wealth of info available on optimising and tuning Tsunami performance...

 

Hope this helps...

 

Happy Modelling,

Aim to Improve,

Prof Klyzlr

[CraigZ]

As the Prof notes, delete that capacitor.  It's an EU mandated thing for noise reduction; the Atlas models here don't have it. 

 

The gist of Bruce Petrucca's low speed tuning a Tsunami is this:

Set it back to basics (ie, get rid of any momentum etc CVs 3&4 = 0, no speed curves), and input 50 into CV209. Then, put 1 into CV210. Set the loco to travel at speed step one (on a 28-step setting), and then increase the value of 210 until it runs smoothly. You may also consider reducing CV209 after that, to get it crawling along. After you're happy, you can then install any custom speed-curve using CV25 and CV29. It's an art, not a science, and all locos may be different, even "identical" ones. 

 

I've done this and it works very well; I do it using programming on the main.

[jhock]

Thank you guys, I will crack open the CVs and give it a go later.

[jhock]

Ok, so sorted out the slow speed running, runs how I want it now so thanks guys.

 

However, clearly did something silly as the lights don't turn on now.

 

Checked all the CVs where set to the default values, which they are.

 

Could I have some how assigned the command to turn them on to a different function?

[jhock]

I did a reset and then sorted the slow speed running again.

[torikoos]

Well done, it can be a bit frustrating, but indeed with patience, a Tsunami can be tamed, provided the loco is electrically and mechanically sound of course.

I've recently moved to ESU Loksound decoders however. They have an auto tune feature, which get's things really close to perfect. The two engines in this video both have been tuned using the auto tune function. The only reason why you see them 'accelerate away' is that I pressed the large step increment button on my Lenz handset while filming, bringing the speed step from 0 straight to 7. 

I will fine tune both with a bit more momentum.