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Led voltage for first run DCC Dash 8-40CW's

Started by pjcs, August 27, 2016, 04:58:22 PM

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Does anyone know the voltage of the leds in the original run of DCC Dash 8-40CW's?  Apparently the latest run are different inside.  I am presuming either 1.5 or 3 volts but not sure.

James in FL

While a digital multimeter will not read exact DCC voltage, what it does read is good enough in this case.
What is the voltage measured at the LED?
Is it possible to measure voltage, with your meter, right at the LED body, or on the board trace, where it goes into the LED? (Leads on the cathode (-) and anode (+) right where they enter the LED after resistor)?
What is the supplied DCC voltage measured at track?
Don't guess or assume, measure it.
While this won't tell you what the LED is rated, it will tell you what the LED is being fed. From there you could probably infer a logical estimate of the voltage of the LED.


The average LED will operate a 3.5 volts.Soundtraxx recommends 680 ohm resistor on their Tsumani for each function negative lead to each LED.Always wonder .I wire up led's for dc locos and use 800 to 1000 ohms . Some here say to use it on the positive side of the LED. I have used them on either pole and it works for both. By the way if it is a older Spectrum and it has a dcc ready board with led lights.It is a second run .The first run of the dash 8 had a split frame and tower mounted trucks that was ok ,but the second and 3rd runs were much better.Now they are discontinued .