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Why do my lights not switch on and off?

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  • Member since
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Why do my lights not switch on and off?
Posted by Mike (London) on Saturday, October 29, 2011 6:51 AM

I have replaced the original board on my MP15 with a TSU-AT1000 Digital Sound Decoder. The wiring is fine. However I have a problem with the lights-front and back.I thought that wiring would be easy-using the exisiting wiring. The new decorder is working, with sound. However I cannot get the front and back lights to swiitch on and off. I have wired the leds using the advice with in the soundtraxx manual -I have hard wired to the common and numbers 8 and 9 and 2 and 3 on the board. I can see the red light on the decorder changing when I press F0

What Have i done wrong?

http://www.soundtraxx.com/manuals/tsuinstallation.pdf

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Posted by BIG JERR on Saturday, October 29, 2011 7:51 AM

not positive,but you mite need a resistor inline w/the led ...Jerry

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Posted by richhotrain on Saturday, October 29, 2011 8:08 AM

Jerry, I don't think that is the problem.  The Soundtraxx web site says that hardware is already on the circuit board to accommodate the use of 1.5 Volt bulbs without the need for external resistors or other electronics.

Gotta be something else.

Rich

Alton Junction

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Posted by tstage on Saturday, October 29, 2011 8:36 AM

Mike,

It could be a couple of things:

  • You need a resistor wired in-series for each LED
  • If the decoder already comes with resistors on the board, you might have the LEDs in backwards

LEDs are diodes so they are "directional"; meaning current can travel through them in one direction ONLY.  (Unlike resistors which can pass current in either direction.)  The white or yellow wire is soldered to the CATHODE (-) or long lead of the LED; the blue (or common) wire is soldered to the ANODE (+) or short lead of the LED.

Here's a handy diagram for understanding the various parts of an LED, as well as determining which lead is the correct lead to solder your wires to:

Lastly, the resistor can be soldered to either LED lead in order for it to work properly.  (For consistency, I like to solder to the ANODE or blue wire.)  A 1K Ohm resistor is a good place to start.  If it's too dim, move to a smaller resistor value.

A couple more things have come to mind:

  • The LEDs might be soldered to different pads on the decoder board than the incandescent bulbs.  It was that way when I soldered LEDs to the NCE SW9SR decoder in my SW8 switcher.  The incandescent bulbs were soldered to one pair of pads and the LEDs were soldered to a different pair of pads.
  • Check your LEDs to make sure that they are indeed good

Hope that helps, Mike...

Tom

https://tstage9.wixsite.com/nyc-modeling

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

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Posted by BIG JERR on Saturday, October 29, 2011 8:40 AM

richhotrain

Jerry, I don't think that is the problem.  The Soundtraxx web site says that hardware is already on the circuit board to accommodate the use of 1.5 Volt bulbs without the need for external resistors or other electronics.

Gotta be something else.

Rich

yes Rich its been awhile since I installed the AT boards in a couple a atlas rs-3s ,but I do remember after all the reading it clearly noted a different setup using leds than 1.5 bulbs (athearn) ,I guess I could get off my duff and try to find the the install sheet . it had to do with the choice of wires used with lighting and it called for resisters for leds as I recall . there is a provision for 1.5 athearn bulbs mite need a cv change too. just cant remember ...Jerry

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Posted by richg1998 on Saturday, October 29, 2011 9:57 AM

The decoder instructions are very clear, You cannot use LED's on the 1.5 volt connections. Those obviously only for 1.5 volt light bulbs.

LED's are polarity conscious and need a 1k resistor.

A couple Tsunami light board decoders come with LED resistors on the decoder.

If all else fails, follow the directions.

Rich

 

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

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Posted by BIG JERR on Saturday, October 29, 2011 12:55 PM

yep thats the way I remember it ,Im glad someone with more knowlege than me chimbed in...thanks ..Jerry

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Posted by richhotrain on Saturday, October 29, 2011 3:21 PM

richg1998

 If all else fails, follow the directions.

Rich

 

LOL, doesn't that take the fun out of it?

Rich

Alton Junction

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Posted by BIG JERR on Monday, October 31, 2011 10:33 AM

No ,I think it should say "if all else fails read the directions 5 times". on the fifth read is when I can say "clearly states ".. cause for me nothing about DCC directions has been "clear" I'm still worried everytime I hit the ON button Embarrassed..Jerry

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Posted by richhotrain on Monday, October 31, 2011 11:14 AM

BIG JERR

No ,I think it should say "if all else fails read the directions 5 times". on the fifth read is when I can say "clearly states ".. cause for me nothing about DCC directions has been "clear" I'm still worried everytime I hit the ON button Embarrassed..Jerry

Jerry, I share your pain.  I am the same way. 

Even on this thread.  After checking the Tsunami decoder specs to verify that a resistor was wired into the board for 1.5 volt bulbs, I failed to catch the what the OP first said and that was that he had wired LEDs to the board.  All along I am thinking he wired incandescents.  LOL  

Rich

Alton Junction

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