Diagnosing Heritage 2-8-8-2 problem

[TVRR]

HI, I have a second run loco that has developed an issue that I do not know how to diagnose- motor vs DCC chip.   While running at a moderate speed it suddenly stopped, all sound continued as if the loco was still in motion. I cut power and the motor restarted, ran maybe 5 min., and stopped. I have reset the decoder several times and restored original CVs without any effect. As soon as power is reapplied sound starts and continues at the same rate and volume as the instant the motor stopped. I strongly suspect the DCC chip but how do I tell for sure? I liked this loco's performance and wonder if replacement decoders are still available?   

[Rasputen]

I assume you have already inspected the connector from the engine where it plugs into the tender?  It is easy to pull on the wires when disconnecting the engine from the tender, which can lead to poor connections. 
I think you can run it with the tender shell off, which should make it easier to find the culprit when the symptoms occur.

[TVRR]

Wires and connections are OK to visual inspection. Just on a whim I took the tender loose and removed the loco. When power was applied the tender went through the start up cycle then immediately reverted to the previous sound pattern. This would seem to indicate that the problem is in the decoder to me. Almost everything else I have is ESU lok sound or Digitrax.
 

[peteski]

Just to be clear, is this the Life-Like/Walthers Mallet loco with the factory installed QSI Revolution decoder?
Which DCC system are you using?

[TVRR]

Yes this is a second run loco with the QSI system from the factory. I'm using a Digitrax  DC50 & a DC 51  and have been for 12 years. The system has worked perfectly with this loco for years and continues to do so with everything else I own.

[peteski]

Yes this is a second run loco with the QSI system from the factory. I'm using a Digitrax  DC50 & a DC 51  and have been for 12 years. The system has worked perfectly with this loco for years and continues to do so with everything else I own.

Not trying to blame the DCC system - I just wanted to know what it is for troubleshooting purposes.

Just to clarify "sound pattern", do you mean it is chuffing as if it was running at some speed (not stopped)?

What was the reset procedure you used?  QSI decoders do not use CV8 for resetting the decoder.
After a decoder reset, did it revert to short address 03?
Can you control any functions using that address?  Like headlights, or bell, or whistle?
Can you read back any CV values on the programming track?

Here is the reset procedure I found at https://dccwiki.com/Decoder_reset

QSI also has a user software reset using the following multi step procedure:

    Place engine on main track if it is still responding to its address. If not responding you may need to use the program track.
    Set CV49 to 128
    Set CV50 to 255
    Set CV56 to 113

As the decoder in the engine resets you will hear an audible response, the horn may sound three times, or it may talk to you. Test the locomotive using address 3.

You can then go ahead and set the loco number as you desire and/or reprogram other CV’s.

    An irritating issue with QSI decoders is when they do get corrupted by a short, the locomotive can exhibit very erratic operation. Resetting it back to default will put you back in control of its performance.

[propmeup1]

I have pretty much the same issue with mine. It's a second run but I had the decoder installed by a pro shop. Soundtraxx Tsunami 2. I ran great but then suddenly decided to stall and hardly get out of it's own way.  Then it doesn't want to move anymore and the sound works as if it's moving when power is applied. Also as soon as I put it on the track the sound comes on. There no longer is a start up, hummm.

[peteski]

QSI Revolution and Soundtraxx Tsunami decoders are like a apples and oranges. The only thing they have in common is that they are sound decoders. I'm really surprised if some problem causes them both to behave same way.

[TVRR]

Thank you for the useful tutorial Peteski. The sound starts immediately @ 4chuffs/sec. and continues without change no matter the throttle setting. You can silence it with f8.   Yes I reset it to 3 with no issues, reads back correctly when changed to 5 also. I attempted to reset with your procedure on the program track, CVS 49 and 50 reset without issue but CV 56 will not read or write, nr appears in the display. Yes I can control bell, whistle sound functions and the lights without problems. Your thoughts?

[peteski]

If you can control the decoder on whatever address you have it programmed to (you can control bell, whistle, and the lights) then try the reset procedure by doing the same reset procedure but writing to the CVs on the main track. Just make sure that the throttle is set to whatever the address the decoder is responding to.

    Set CV49 to 128
    Set CV50 to 255
    Set CV56 to 113

After the last step do you hear any audiable response?

[TVRR]

No audible response detected. Decoder will not program CV 56 on mainline with OPS programing either.

[mmagliaro]

I lost track of the motor behavior after the initial description of the problem.  Is it still the case that if you cut power and wait a little bit, you can turn it back on and the motor will run for a few minutes before it quits again?  Or is the motor not running at all now?

[TVRR]

Hi Mike, The lack of motor function is full time now. It restarted after it's first motor shutdown ,no response since. When attempting to reset, CV 56 will not read or accept changes on either the main in OPS or the program track.

[peteski]

No audible response detected. Decoder will not program CV 56 on mainline with OPS programing either.

Since in OPS mode you can only write CVs (no readback), do you really know that the decoder is not accepting write to CV 56?  Or are you hearing the value of the other 2 CVs spoken in human voice as you are programming in OPS mode (but when you write CV 56 there is no announcement)?

[TVRR]

Placing it back on the Prog track and attempting to read CV 56 still shows "nr", so I'm making the assumption it did not take. BTW, it reads every other CV I've checked.