# very puzzling behavior



## lownote (Jan 3, 2008)

Here's the situation: I had burned out the motor in an aristo mikado drive. I got a replacement and installed it.

The loco has a QSI Decoder in the tender, the tender is wired for power pickup on all 8 wheels and connected to the loco. The loco headlight is wired to be always on, from track power, and the tendrr has marker lights which are similarly always on. The decoder plugs into the QSI "magnum" adapter


I went out today to try it and when I placed the loco and tender on a live DCC track, I got sound. But when I touched the throttle it made the sounds of going to full speed while not moving. I quickly took it off the track. I checked all the connections and put it back on the track--this time I just got a buzzing sound

But the lights in the tender and the loco both still worked.

So I took it to the bench and inserted a shorting plug into the socket. I applied DC and everything worked just fine. 

Back outside. I have a track with DC on it for a trolley--the loco with the QSI decocder ran just fine on that. So did the loco when the shorting plug was installed. 

But when I placed the loco with the shorting plug in it on the DCC track, I got the same buzzing noise. Now that's puzzling. 

So--on DC power, the loco seems to run just fine with both the QSI decoder AND a shorting plug

On DCC, the loco buzzes and won't move with both the shorting plug AND the decoder. Bu the lights in both the tender and the loco stay on. 


I'm pretty mystified about this> Any suggestions?


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## zubi (May 14, 2009)

Lownote, you probably burned the decoder too... the moral is, in locomotives, burn coal, meths or gas! Zubi


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## lownote (Jan 3, 2008)

this is a brand new decoder--yes, the old decoder burned, but this is a brand new one


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## lownote (Jan 3, 2008)

Well I just tried it in a different loco and got the same buzzing, so it must be the decoder. Maybe QSI can fix it. The odd thing is still responds to the "reset" procedure and announces "reset."


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## Greg Elmassian (Jan 3, 2008)

Yep, but the output transistors are gone. 

The microprocessor still functions. 

Regards, Greg


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## George Schreyer (Jan 16, 2009)

With the shorting plug, it SHOULD buzz when placed on DCC powered track. If it does the same buzzing with the decoder installed, the NEW one is blown up too. This indicates a wiring problem. Have you made POSITIVELY sure that the motor is isolated from the track?


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## Greg Elmassian (Jan 3, 2008)

I missed that! Yep, feed AC into a DC motor it will buzz... don't do that! (dcc input with no decoder) 

Regards, Greg


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## lownote (Jan 3, 2008)

I must not have--I thought it was, but I'll have to disassemble it and double check


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## George Schreyer (Jan 16, 2009)

Actually, you can run a DC loco on a DCC system. Address it at adress 0 and it will run. It'll sound bad and it's hard on the motor, but it should run.


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## Greg Elmassian (Jan 3, 2008)

NCE took that capability out of their systems one or two rom revisions ago. They said there was not much call for it, and they wanted the code space for more features. I think the Digitrax and several others still support it though. 

Regards, Greg


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