# Bachman 3 Truck Shay won't run!



## Jerry Barnes (Jan 2, 2008)

Buddy of mine got a new Bachmann 3 truck shay, has the sound system in it, runs on track power. Sound came on right away, but no movement from the trucks. Tried all the switches behind the smokebox door, but nothing. Any ideas?


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## Steve Stockham (Jan 2, 2008)

Other than take it back and either get a different one or a refund?


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## nkelsey (Jan 4, 2008)

Couple of areas of failure possible.... 

Trucks connect to the chassis with a spring loaded plunger. If there is no load on the trucks, ie loco is on its side or in the air, plungers do not make reliable contact. They can also stick and not connect. 

Secondly, wires tend to disconnect very easily from the PC board and the tender plug board...solder joints fail.


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## Greg Elmassian (Jan 3, 2008)

Jerry, stock sound system or aftermarket one? Need to confirm this. 

If it is the stock one, that is very strange, because it is all the same board, so when power is applied, it's to all the circuitry. The only possibility I can think of there is that the decoder has been reprogrammed to not run on DC... this is possible, need to check CV 29. 

If it is aftermarket, then it's possible that the power for the sound board is picked up from a different place than the motors, but this sounds unlikely. 

I'd do the DCC check as long as you are sure it's the stock sound system. 

Regards, Greg


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## digger (Jan 2, 2008)

Another possibility is that one or more of the wires in the four-pin plugs from the loco to the 3rd truck has failed. These are very fragile connections on the female plugs (wire is very fine and has almost no strain relief). I have had 4 of these break and they are a bugger to fix. I will probably end up going to a more robust configuration.


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## Jerry Barnes (Jan 2, 2008)

Says sound on the Bachmann box, so I assume it is what comes with it. We were not using DCC, just DC, know NOTHING about the DCC.


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## paintjockey (Jan 3, 2008)

The loco needs to be put on a DCC programming track and told to run on DC. I did work on one for a friend that had the same problem. I don't remember the CV that needs set though, sorry. 

Terry


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## Greg Elmassian (Jan 3, 2008)

CV29.... per earlier post... would be weird that DC was "off". Jerry, any possibility that it's really not completely new? 

If you get it to a DCC system, a full decoder reset would be the first thing I would do. That also will default to DC operation I believe. 

You should be able to use the Soundtraxx Tsunami commands if no programming manual came with the unit. 

Regards, Greg


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## TonyWalsham (Jan 2, 2008)

Jerry. 
What type is the power supply/controller you are using. 
It *MUST* be linear DC and *NOT* pwm. The latter may cause all sorts of undesired reactions in the DCC decoder.


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## Greg Elmassian (Jan 3, 2008)

Tony, if it is the stock unit, it's a single DCC decoder... it won't make sound but not run, because the motor control and the sounds both run from the same microprocessor... the Quasinami... 

Greg


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## TonyWalsham (Jan 2, 2008)

Sure Greg. 

But who is to say that PWM cannot affect just the motor part? PWM can do all sorts of weird things to DCC decoders.


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## Jerry Barnes (Jan 2, 2008)

Hmm, I did have the Aristo unit set on PWM. He's got a small Bachmann transformer I gave him, he'll try it on a piece of track at home before sending it back in. Neither of us have any DCC stuff, nor know anyone here in Nebraska that has it.


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## TonyWalsham (Jan 2, 2008)

Hello Jerry. 

You also need to make sure the Bachmann controller has a clean linear output. Many of those el cheapo speed controllers inject a pulse (as distinct from pwm) into the output to get "sticky" motors to respond. 
DCC decoders do not like that pulsing either.


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