Sumpter Valley DCC misbehaving

A

adverse camber

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I have an LGB Sumpter Valley Mallet with preinstalled sound and DCC. A couple of years ago it started to suddenly start up (very slowly) on its own for no very obvious reason, but it was infrequent and I put up with it. This year I installed an ESU chip with sound into a new Shay, and now when ever I start the Shay the Mallet takes off at brisk pace. It has caused several accidents and I now have to keep it isolated in a siding all the time or off the track.

I tried reprogramming and have altered the cv's on both the locos (mallet and Shay) without any effect and it still happens.

Last week I opened up the Mallet (quite a job) with the intention of removing the old DCC chips and installing two new ones which I had spair, but I found all the circuit boards are integrated and there was no obvious way to replace the DCC chips with out gutting the whole thing and starting again, given the need for a sound and DCC control that will be quite expensive.

Has anyone else encountered this problem or have any suggestions as to how to solve this? I have 20 other locos with a variety of DCC chips installed (ESU, LGB and Massoth) and this is the first time I have hit an incompaibilty problem of this sort. I use a Massoth Diamax control sytem and radio controlled Diamax navigators.

Thanks for any suggestions.

Adverse Camber
 
I dont think that there will be any dip switches present on the LGB PCB when the decoder is r presinstalled ( ie factory fitted & integrated)

Have you tried restting the SVM back to factory installed settings?

if you have no joy it may be that a component on the PCB is causing the problem, and installing a replacement decoder or sound decoder may be an option, in which case it would be quite a simple job to wire everything to the decoder and discard the LGB PCBs.

Nice loco the SVM somtimes wish I hadnt been so quick to sell mine ( & the Uintah Mallet ) but there you go.
 
Just another thought I have had, I know that a couple of other G scale enthusiasts have experienced, similar problems with ONLY certain locos, suddenly starting, stopping , reversing or randomly initiating sounds without being commanded to do so! These were on radio controlled digital systems, no reason could be found for this occurance except it was considered that outside radio influences may have had something to do with it.

When one guy brought his offending locos (2) to my line (RC digital) they both performed perfectly, which seemed to prove that there was some outside cause for the problem . As far as I am aware the problems still occur, but one of them said that when he hard wired the Nav. to the central station, there were no problems at all.

I cant think of a reason why the Introduction of the Shay should cause probs though.

Let us know how you get on with this one!:thumbup:
 
Thanks for the advice everyone.

No dip switches on the integrated electronics when i opened it all up. I have tried resetting the DCC to factory settings without any joy. Please keep the ideas coming.

I suspect I may have to tear out all the electonics and wire in a new massoth sound/DCC chip but I that is expensive!

AC
 
Do you have anyone else in yr area with a line on which you could test the loco in a different enviroment to your own?

I cant help thinking that the problem may lie in RC interference and not the loco itself
 
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