DCC Running

[Martin Jones]

I am having trouble controlling my Class 73 using DCC.

Its the GBRf version, lovely loco..

I use a simple Bachmann EZ controller which works on all my other loco's and units.

However ot won't control my Class 73, I have tried two Bachmann Decoders the 554 and 557, and a Hoprnby Saphire but all without any joy.

Has anyone else experienced similar issues and give me guidance on what to do.

[Andy Dapol]

Martin Jones Could you give a brief description of the problem you are having please?

[Martin Jones]

Hi Andy, when the loco is placed onto the track it just takes off on it's own and you can't stop it, it just moves off at a slow speed without any movement of the controller and it can't be stopped. As I said I have tried three different decoders, all brand new.
Regards, Martin

[Andy Dapol]

Thanks. You say other models operate OK with your EZ command? Do they operate OK with one of the three decoders you have tried in the 73?
If this is the case, it could be that there is a partial (high resistance) short between a pickup and motor output in the loco, it's not something I have come across before, but assuming a good decoder and controller, a loco fault could cause this. If so, we need to have it looked at for you.

[Bulver]

What loco no. Have you allocated to it, Martin? Sounds like you are either using loco no.10 (if you are using the basic Bachmann controller) which acts as a DC supply for non-decoder fitted locos. Alternatively, it could be the decoder is set to run on both DC/dcc and this has proved sometimes to cause loco runaway. I don't know how you can alter that on the basic controller, although you can on the Dynamis by altering the CV. Can't remember the CV number at present, but will check it out if you would like me to. Just found the CV no. is 29
Rod

[Martin Jones]

What loco no. Have you allocated to it, Martin? Sounds like you are either using loco no.10 (if you are using the basic Bachmann controller) which acts as a DC supply for non-decoder fitted locos. Alternatively, it could be the decoder is set to run on both DC/dcc and this has proved sometimes to cause loco runaway. I don't know how you can alter that on the basic controller, although you can on the Dynamis by altering the CV. Can't remember the CV number at present, but will check it out if you would like me to. Just found the CV no. is 29
Rod

Hi Rod
Thanks for your advice.
The loco was set at 3, decoder unchanged, it was at the factory setting for a new decoder.
Looking at the Sapphire booklet it sais CV29 is the directional setting ??
Martin

[Bulver]

Hi Martin, sorry, after I wrote the post I noted that you were using the EZ command controller. Yes, loco 3 is the default and so obviously my suggestion was duff. As far as the Sapphire decoder is concerned, I have checked the instructions, and, as yer, cannot find that part of CV29 that relates to allowing or disallowing dc running. However, I have checked various reputable sources, and this is the cv to alter. Apparently switch 4 allows this change to be made. It is some while since I did this, so cannot be sure of the procedure.

[Martin Jones]

I found a link for CV29....

2

4

DC operation

Deny (off) or allow (on) operation on analogue DC current (usually recommend to set "off" unless analogue is really required).

[peteb]

CV29 combines a number of things and only one bit controls whether or not the loco will respond to DC.

You need to put the loco on the programming track (don't know if the EZ Command can do this), read in the value of CV29, subtract 4 from that value and then write it back to CV29.

If your system can't do the programming track, then try putting a value of 2 into CV29. This sets the normal defaults for a short address (like 3) but with DC operation turned off.

There is a useful calculator for CV29 on the 2mm association website, you tick the boxes you want and it tells you what value to put in CV29:

http://www.2mm.org.uk/articles/cv29%20calculator.htm

IME, runways can often be caused by the loco thinking it has a DC signal so turning off the DC option in the CV can often help.

BTW, my class 73 runs nicely on DCC with a Loksound decoder I bought from Legoman, but I do have to keep the pickups clean. After a lot of use it starts to stutter, and I go over the pickups again with TrackMagic, and that restores it to perfect operation again. Eventually I will get around to modifying the circuit board so I can control the cab lights from spare functions, instead of them being on all the time.

Regards,

Pete