More DCC light wierdness

 
  Gremlin Assistant Commissioner

Hi All Smile


I have installed a TCS M4 decoder in a locomotive and reset it to factory defaults.  I am only using the motor control and the white/yellow headlight wires.



I have the blue wire connected to both anodes of the LEDs and the white to one cathode and the yellow to the other cathode.  The LED connected to the white switches on and off when using the appropriate function, the LED connected to yellow is on all the time, even if headlights are selected off.



I have reset the M4 to factory defaults several times, it still happens.  I have tried a different controller and it still happens.

I have wired all my other decoders in this fashion, using the blue wire as a "bus" for the lights and using the function wire with resistors for the individual lights.



Some suggestions please?

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  Marbelup Station Master

Location: Perth, Western Australia
It sounds like the decoder output is faulty.

Can you wire the LED to a different function output and reconfigure the function mapping accordingly?
  Gremlin Assistant Commissioner

Haven't tried that, but I did try two different decoders...will try others, glad I have spares but not too happy if I have a run of bad TCS decoders Sad
  bjviper Chief Commissioner

Location: Brisvegas
Is the wiring to the LED's all yours, or is it the original factory wiring?
  Gremlin Assistant Commissioner

All mine, but couldn't be more simple - wires to pickup, wires to motor, blue to both LEDs, white to one LED, yellow to the other.  Resistors in place.

Each LED works when connected singly, and in a tester.
  Marbelup Station Master

Location: Perth, Western Australia
Do you have a decoder tester?  That can make testing easy especially if the decoder has a compatible plug.  I have a basic NCE tester which has LEDs for all four function outputs.

It is strange that more than one decoder displays the same symptoms.

Have you tried configuring the decoder to have individual function buttons for each function output?  I assume the default is for directional headlight control which is generally not prototypical anyway.  Maybe there is something strange with the factory default settings and th decoders may work Ok with specific function mapping?

I would be tempted to wire up 4 LEDs, if you don't have a tester, and see what works with the decoder set up to use F0-F3 to control all four outputs individually.  

If the decoders can't be configured to work correctly, they should be covered under warranty.

I am not very familiar with TCS decoders, so I can't help with specifics re configuration.  I have used one or two some years ago and not had any problems.
  steven_h Train Controller

Location: Melbourne, Australia
The LED that stays on, any chance it's 'flickering' very quickly?
Could be that it's around the wrong way. Try reversing the legs on the LED that's on all the time.

(Also, a photo could help us here)
  TheBlacksmith Chief Commissioner

Location: Ankh Morpork
The LED that stays on, any chance it's 'flickering' very quickly?
Could be that it's around the wrong way. Try reversing the legs on the LED that's on all the time.

(Also, a photo could help us here)
steven_h
If the decoder is working correctly, it would not  make any difference which way around the LED is connected, it should not come on at all.
  Gremlin Assistant Commissioner

And the answer is.....

Dodgy decoder(s) - three of them!

TCS finally replied and suggested that a transistor may have gone out-of-spec causing the yellow wire to be hot all the time, suggested using the green or purple and remapping light function.  Did that and it worked perfectly.  That I now have three TCS M4 decoders with the same problem, and that TCS "knows" about a faulty transistor, makes me wonder if this is a bit more widespread than just me?

After two years of trouble-free usage of TCS decoders, I have now had six (three M4, three DP2X) fail or work incorrectly.  Quality control problems?

Thanks for all who helped, especially those who suggested the wire swap as a test Smile
  Marbelup Station Master

Location: Perth, Western Australia
At least there was a logical explanation.  So now you have some 3-function decoders!

You would still be well within your rights to ask for replacements if you not happy with the outcome, especially given that TCS have admitted there is a problem.
  Aaron The Ghost of George Stephenson

Location: University of Adelaide SA
Hmmm this is fishy, I am almost inclined to imply that there was actually a wiring fault somewhere in the yellow circuit causing the function transistor to short (as in on the board, not necessarily by the op's hand). The reason I imply this is that it's quite unlikely (even with a dodgy batch of transistors) that three decoders could each get one faulty transistor (out of four) always installed in the same location. Mr Poisson and I don't always get along (especially when I call him 'Simmo') but this just does not look like his work to me. I'd believe a distribution of 'faultiness' but a exact repetition strikes me as a bit of a stretch, it may well be that 'Daniel Handler' has somehow aligned the series, strange things happen, but only with a reason.

In any case, it's just about absolutely irrelevant, TCS will replace the decoders no worries, with or without admitting a problem, it's what they do.
  Aaron The Ghost of George Stephenson

Location: University of Adelaide SA
Oh, and if you ever want to test a dead function like this again, remapping the function is a pain if you don't need to. Test on green/purple and function 3/4 first, if this causes correct behaviour then dig out the instruction sheet and program/remap away.
  railmod Chief Train Controller

snip

In any case, it's just about absolutely irrelevant, TCS will replace the decoders no worries, with or without admitting a problem, it's what they do.
Aaron

I agree with Aaron on this point - TCS replaced 10 WOW100 decoders I had hassles with no questions asked, can't ask for better than that.

Cheers Alex.
  Aaron The Ghost of George Stephenson

Location: University of Adelaide SA
I agree with Aaron on this point - TCS replaced 10 WOW100 decoders I had hassles with no questions asked, can't ask for better than that.

Cheers Alex.
railmod
1000 to 1200 odd bucks worth of decoders? That's taking the no questions asked return thing on the chin!

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