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Decoders


Barking wag

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hi and help,

i recently purchased an 8 pin decoder where one wire was no longer attached to the board that plugs into the socket. when plugged in the loco made a whirring and did not move, I was about to switch off when there was a puff of smoke. Is this the decoder or an issue with the loco?

Many thanks in advanCe

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Can you tell us what decoder brand model and the colour of the wire that was not attached. Did it happen to be purple by chance?

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You will notice that the plug has 8-pins and the decoder has 9-wires. The purple wire is hard wired to the loco to provide an additional function output. If not required then tape it safe.

 

Blue wire is common positive, white and yellow wires are directional headlights, green wire is additional function 1 and purple wire is additional function 2.

 

Rob

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As Rob said above, the purple wire is supposed to be unterminated, that is normal for that decoder.

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Getting back to the original question. One would need to know where the 'puff of smoke' came from (loco or decoder) to answer the question. Even then, it may not be a straight cut answer, the decoder may have given the 'puff of smoke' because of the loco. Puffs of smoke, usually occur when there are 'short circuits'. You will need to do some testing to prove what the fault is....see below.

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You will need to do some diagnosis (voltage & resistance measuring) with a multi-meter to gain a clue as to what might now be faulty. If there is a short circuit and where the short is. Shorts are more difficult to trace than 'open circuits' because 'short circuits' require the electrical circuit to be broken down into discrete electrical segments to isolate the short from other parts of the circuit.

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Then again, if the motor will no longer do anything, it is possible that the decoder has overloaded and blown. Obvious components to check are the 4 larger rectangular black components (the diodes in the bridge rectifier at the input to the decoder). If one or 2 of these look charred compared to the rest, that will be your problem. 

 

Then in the question is what caused the overload? 

 

And a whirring motor and no movement sounds like the gear train between motor and wheels is slipping. 

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Whirring - or whining? If whining, I'd look for a short between wheels and motor bypassing the decoder. The whine/whirr could be the motor oscillating, as per the other thread about select overload.

BW doesn't say what the loco is/was, so it may be a converted 'live-chassis' item. Also he doesn't say what the controller was that he used.

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BW doesn't say what the loco is/was, so it may be a converted 'live-chassis' item

That is true Eric and it would also fit in with the 'puff of smoke' observation, but he also said "when plugged in the loco" which infers a socket was there, inferring a DCC ready loco. Of course, BW could have put the socket in there too, as part of the DCC upgrade. As is so typical, not enough information is given in the original post to allow a robust assessment of the issue.

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Many thanks for the detailed advice, I am not nights so just picking up on the messages now and I'll get back to you.

to note not a conversion DCC ready with socket and the loco is an 08.

Controller Bachmann EZ command. All other locos running as usual.

the puff of smoke was from decoder.

if gear train slippage then is this return to manufacturer issue or one that can be fixed relatively easily?

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Generally gear train repairs are as easy as ensuring the gears are meshed or replacing damaged cogs, but as always if the loco is under warranty then send it back rather than try to fix it yourself, as any fiddling could void the warranty.

Rob

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Generally gear train repairs are as easy as ensuring the gears are meshed or replacing damaged cogs, but as always if the loco is under warranty then send it back rather than try to fix it yourself, as any fiddling could void the warranty.

Rob

I bought a new decoder today and the loco is not working. No whirring or even picking up electric just dead. I am not sure it's the gearing but over 12 months since I bought the loco. Anyone know of someone who can repair. 

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