Bachmann 36-557 (Repackaged Soundtraxx?) 21 pin.

[Star-rider]

This is not critical, but an issue has arisen which confuses me and I’d love to know the explanation…

 

I’ve been spending some time trying to regularise the speed of my locomotives so that all will circuit my layout in 3 minutes (so far as gearing will allow) at speed step 32 of 128.

 

Most locomotive / decoder combinations seem happy for me to do this by adjusting CVs 5 & 6 but I came across a GWR 30XX ROD which I had fitted with the above decoder. It was circuiting in about two and a half minutes so I set about trying to slow it a little. A read of the CVs suggested that they were at default maximum. I first tried 240 / 120 in CVs 5 &6 with no effect on the speed. Knocking them down to 220 / 110 made no difference, and so it went on reducing by increments down to 20 /10 with still no impact on the speed.

 

I shoved the ROD to one side and carried on working through the roster. Eventually an “Earl” came up which was fitted with the same type of decoder – the results of attempting adjustment were the same, I can’t slow it down to the desired datum speed.

Confusingly, I have another “Earl” but that is fitted with a Loksound decoder and although it is exactly the same model as the first Earl it gives me the opposite problem – even with CV5 up at maximum it is a five minute job to get round the layout. As the two locos have the same mechanics and motor it is obviously a decoder voltage output issue, but why would they vary so much and not be adjustable?

 

I’m using a Dynamis system with a Pro-box.

 

As I say, it is not the end of the world, I can cruise at the right speed with more or less throttle – I was just craving a bit of consistency!

[Izzy]

You won't get any joy out of cv's 5&6 because these decoders don't support them......that's why playing with them had no effect........guess how I know....! There is only start voltage cv4, or setting an individual speed table. The latter is easy with JMRI/decoder pro but not so good otherwise.

[Nigelcliffe]

RTFM ?    Both decoders mentioned don't play ball in the simple way you're trying to adjust them.  The use of CV2,5,6 is optional in the DCC standard, and the makers have chosen to not use them.

 

Soundtraxx MC1 (which is what I think Bachmann badged).  Has pre-set speed curves in CV25, or you set the full 28 point speed curve.   

 

ESU.  Has end points (CV2, CV5), but all intermediate points are set in the 28 point speed curve.   Possibly the settings for motor control are meaning the loco is running slower than ideal - there is an "auto-tune" option to set those, or you can set them manually. 

 

 

 

- Nigel

[Star-rider]

1 minute ago, Izzy said:

You won't get any joy out of cv's 5&6 because these decoders don't support them......that's why playing with them had no effect........guess how I know....! There is only start voltage cv4, or setting an individual speed table. The latter is easy with JMRI/decoder pro but not so good otherwise.

I did wonder, although the instruction card suggests a range of 0-256!

 

It looks like I have been misinformed...

[Star-rider]

2 minutes ago, Nigelcliffe said:

RTFM ?    Both decoders mentioned don't play ball in the simple way you're trying to adjust them.  The use of CV2,5,6 is optional in the DCC standard, and the makers have chosen to not use them.

 

Soundtraxx MC1 (which is what I think Bachmann badged).  Has pre-set speed curves in CV25, or you set the full 28 point speed curve.   

 

ESU.  Has end points (CV2, CV5), but all intermediate points are set in the 28 point speed curve.   Possibly the settings for motor control are meaning the loco is running slower than ideal - there is an "auto-tune" option to set those, or you can set them manually. 

 

 

 

- Nigel

Thanks Nigel - I know that some decoders don't have an adjustmant available to CV5 (I think the Hornby TTS?) but that was obvious from the instructions.

 

The card with the Bachmann decoder suggested that there was a range to work with, which is why I wasted my time.

 

ESU decoders are my preference (reliable and adjustable), but sometimes it is a case of what will physically fit, what is to hand or what the shop has on the shelf hence there are a few in the fleet that I am not familiar with.

 

Pete.