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Setting up my test track pre programming of all my new decoders and I'm wondering if anyone has found a suitable value for a "Universal" resistor for limiting current to all the different manufactures decoders?
 

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DT
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Where do you get this idea from Brian?

I'm not too sure if playing with the DCC signal/power BUS but adding resistances is such a good idea. Perhaps it will work, but perhaps it will mess around with the decoder that is expecting a certain voltage to function correctly.
 

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Discussion Starter · #3 ·
Hi Doug
My understanding is that you should always place a newly chipped loco onto a "Test track" before doing anything else.

As the resistor, which is in series with that section of track and the decoder, will prevent the decoder being destroyed due to possible wiring or decoder defects. In other words the decoder can't receive full power and it won't be blasted into space!
I'm thinking of using a section of siding which will be completely insulated from the rest of the layout.

I picked this up from the MRC site, as this is where my control system comes from... http://www.modelrec.com/resources/trainSou...progdecoder.pdf
What isn't stated is the value of the resistance?
 

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You shouldn't need a resistor, Ive never used one and that includes some MRC decoders. NMRA standards state that a programming track should provide a low power DCC signal, this is to protect an improperly installed decoder from damage should it receive full layout current. As the MRC/Gaugemaster prodigy advance has a seperate programming track, and is NMRA compliant, you don't need a resistor as there is built in protection in the system.

I've just read that page and I can see what they are saying, however if you place the loco on the programming track, and can program it and readback it's address then you can be sure the decoder is working fine and is installed properly, so you don't need a special test track.

Such things may have been necessary before we had seperate programming track outputs on systems, but I don't really see a point to now.
 

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DT
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I haven't seen that before.

On the programming track, you 'read' the decoder's default address - CV1 usually equals '3'.

If you see that then there it is installed correctly. I don't see how you can really mess-up an installation. Perhaps you can cross the pick up wires or cross the motor wires, but it is not that serious. Some motors are hard to isolate due to a conducting chassis, but the test track will not help that much.

You can't drive the motor on the programming track so there is no danger there. I have mine on a fully-isolated siding so it is not possible to accidently drive a loco in whilst programming another. The micro-switch on the points switches between programming and DCC modes.
 
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