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Decoder Runaway Sound (but stationary locomotive)

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  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,776 posts
Posted by wjstix on Tuesday, September 6, 2022 9:03 AM

If it were me, I would put the original sound decoder back in the original engine's tender and see if it runs well or not. If so, I would just run the engine with the original decoder, and try the new decoder in a different engine. If that engine has the same backing up problem, it's for sure that it's something with the decoder. If you can't figure out a way to get it to work by adjusting the CVs, send it back under warranty for repair or replacement.

Stix
  • Member since
    August 2022
  • 2 posts
Posted by AJB5054 on Monday, September 5, 2022 5:36 AM

OK, took a while to get around to it but I ran a test.  With another locomotive's tender (containing the factory sound chip), the loco runs fine.  That's a shame as it does suggest a decoder issue, but the decoder was brand new.

I took it apart and cleaned a little gunk out of the bearings, which does seem to have made it run smoother.  Once it went back together, the problem started occuring a lot less frequently (but it's not completely gone).  I've reset CV95 to the default, but since the problem doesn't happen every time, I'll have to wait and see if it's gone for good.  Thanks for the advice!

  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,776 posts
Posted by wjstix on Tuesday, August 23, 2022 11:38 AM

Yes I would try a decoder re-set and try running it on 03. It's possible you've accidently adjusted CV95 - Reverse Motor Trim to a very low number (default is 128) so the motor is getting little power in reverse, even though the throttle is telling the 'chuffs' that the engine is moving OK.

If the engine ran normally before - either on DC, with a regular decoder, or the Bachmann Sound Value decoder - then it shouldn't be a physical problem with the engine.

Of course I'm assuming you connected all the wires up correctly! Wink

Stix
  • Member since
    March 2011
  • 1,950 posts
Posted by NVSRR on Tuesday, August 23, 2022 10:19 AM

Actually sounds like a program issue to me. Some5ing with the speed steps in the chip vs the throttle setting.    When the throttle is at zero the chip might be at setting 4 or 5 or something. And adding that one incrime  tin tease is enough for the decoder to increase motor voltage just enough to make it move even if it is at only setting on on the throttle. The motor control cv's might be off somehow.  Did you try running a rest on the decoder then reprogram the decoder?

What speed step range ar you using? 

shane

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

  • Member since
    August 2022
  • 2 posts
Decoder Runaway Sound (but stationary locomotive)
Posted by AJB5054 on Tuesday, August 23, 2022 5:53 AM

Hi Everyone.

I'm at my witt's end trying to troubleshoot this issue, so figured it was time to actually use my account here and humbly ask for some assistance.

 

I've just finished installing a Tsunami TSU-BH2 into a Bachmann 2-8-0.  All seems to be working except for running in reverse.  When I try to do so, the sound immediatly chuffs so fast it barely sounds like chuffing, while the loco doesn't move (but makes a slight buzzing noise).  This is at speed step 0 (out of 28).  Moving to speed step 1 causes the loco to lurch forward, and then start running a bit more normally (though not very smooth, still lurches a bit).

So, has anyone encountered this sort of behaviour before?  At this point, I'm not even 100% sure it's electrical rather than some sort of mechanical glitch.

Oh, and the DCC system it's running on is an NCE Power Cab. 

Thanks for any advice!

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