Snakebit Loco

Model Railroader Electronics and DCC
1

I have this ATH GP-9 with a Tsunami OEM decoder, not much more than a year old. Just before the warranty period was up the decoder failed. Sound, light worked ok, but theer was no motor control. The nice folks at ATH said send it back and we’ll replace the decoder - no charge. After a few weeks it comes back with a new decoder - same decoder type of course. Quick test and it works just fine. So its off to the programming station (JMRI) to get setup for the consist it will operate in. After the last tweak (speed table adjustment) its placed on the RR. Nice and smooth in forward, but wait…in reverse it shorts out the RR - what? Honestly now…

I’m guessing the best bet is to remove the shell, look for possible short paths and fix them, and replace the decoder with ??? Maybe a QSI version. Open to suggestions.

Might nick name this one to ‘old snake bit’…

Rick

2

Sounds like the similar thread about the RDC that only goes in one direction regardless of the throttle direction!

http://cs.trains.com/mrr/f/744/t/245389.aspx

I can not see any way a decoder can run a motor fine in one direction then completely short in the other… as Sherlock Holmes would say, “The game is afoot”!

It will be interesting to see what the cause of this behavior is.

In this “quick test” did the engine run OK both forward and reverse?

Just like the RDC thread, maybe look at programming, consisting, throttle issues?

Very curious, indeed… Ed

3

I had a Tsunami with that same problem. It would run fine in forward and short in reverse. The Tsunami tech I emailed said “It’s probably a bad motor driver in the decoder.” So, I guess the decoder community is familiar with this sort of thing. I sent it back, they tested it and gave me a new one.