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Digitrax DCC Decoder install in N scale Mikado boiler

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  • Member since
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  • From: Jacksonville, FL
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Digitrax DCC Decoder install in N scale Mikado boiler
Posted by gatrhumpy on Monday, February 14, 2011 8:39 AM

In photos 12 and 13 of the following link, it does not show where to connect the blue wire. Can someone tell me where to connect it? The reason why I ask is that my headlight does not light up when I run it.

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Posted by gatrhumpy on Monday, February 14, 2011 10:43 AM

No one knows where the blue wire is supposed to go?

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Posted by Rabid on Monday, February 14, 2011 10:53 AM

gatrhumpy

In photos 12 and 13 of the following link, ...

I don't see a link.

HO & N scale. Digitrax DCC. Mostly L&N (Louisville and Nashville) railway using a mix of brands. Back in the hobby after a looooong absence.

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Posted by gatrhumpy on Monday, February 14, 2011 11:10 AM

Sorry.

 

Photos 12 and 13.

http://www.powersteamguy1790.com/2.html

 

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Posted by woodone on Monday, February 14, 2011 1:08 PM

The Blue wire is not used.

Did you cut the trace as shown in photo 11. The head light will work off the right rail wire(red) and the white wire. Again the blue wire is not needed.

I would heat shrink the end of the blue wire so it will not short some place . It is hot at all times. 

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Posted by gatrhumpy on Monday, February 14, 2011 1:17 PM

The blue wire has been shortened and is completely covered.  Yes, I did cut the trace, otherwise I would have a short.

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Posted by gatrhumpy on Monday, February 14, 2011 1:23 PM

I still don't know why the headlight is not lighting up. I press the "Headlight" button on my NCE Powercab throttle, and nothing happens.

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Posted by woodone on Monday, February 14, 2011 7:08 PM

Did you check the LED? Might be bad. Take a good LED and test on the Red and the White. Don't

 forget a resistor. This way you can see if it is the LED or the output is bad on the decoder  

Who's decoder?  Do a factory reset?

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Posted by gatrhumpy on Tuesday, February 15, 2011 4:59 AM

It's a Digitraxx decoder.

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Posted by woodone on Tuesday, February 15, 2011 10:20 AM

I would try a factory reset, then test run on address 3 and see if the light works. If not, then test the LED.

If the LED is OK,  I would switch the white wire to the yellow. You are not using the reverse function so you can remap for the headlight.  I would guess that he decoder has a bad output function on the white wire. Before you do the above I would wire a NEW  LED and resistor up to the red and white wires and see if the decoder is working on that output.

 

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Posted by gatrhumpy on Tuesday, February 15, 2011 1:00 PM

I'll have to see if I have any resistors. How would I wire it up? Just touch a wire from the red contact point before the resistor and another wire from the white contact point to see if it lights up the LED?

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Posted by woodone on Tuesday, February 15, 2011 2:06 PM

Take the new LED and solder a 1K resistor to the long lead of the LED. This is to positive lead. Now solder the resistor to the red lead on the loco. On the LED's other lead hook up the white wire.

This should make your LED light up when you turn on the H/L  in the forward mode.

Did you check to see if the LED was good on the Kato board?

One thing I always have on my work bench is a 9 volt battery with a 3-16 volt buzzer attached to one lead. And just a test lead on the other lead. Hook the buzzer to the positive lead of your battery. Now you can test a LED by hooking ups the leads to a LED. The positive lead to long lead on the LED and the negative lead to the short lead of the LED. The buzzer will sound and the LED will light up . The buzzer goes between the battery and the test lead.

I also use this to check for shorts or continuity.

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Posted by rrinker on Tuesday, February 15, 2011 7:40 PM

 Test the LED as above - but DISCONNECT THE DECODER FIRST. Feeding voltage back in can/will blow the function output. There's already a resitor on the Kato board and it would be in the LED circuit if you did the install and connected the wires EXACTLY as shown on that linked page. It's using half-wave power which is why the blue lead is not required. There's probbaly not enough room to stuff another wire up through the boiler shell, and to hook it up like a normal light you'd have to remove the resistor on the Kato board and add in a 1K resistor somewhere.

 Since the resistor is already there, you should be able to light up the LED connecting the 9V battery - to the white wire and + to the red wire - again with the decoder unplugged!  If the LED works this way, you should be good - test the decoder and measure the voltage between the white and blue with the headlight on to see if the problem is in the decoder. If the LED does not light this way, try reversing the 9V battery - if it lights then, the problem is that the LED is on backwards it wouldn;t be the first one to slip out of the factory with the lights wired backwards. Or just carefully compare the LED to the picture - meaning look at the 'guts' of the LED and make sure it is oriented exactly as shown in the pictures from that site. If it's not, it won't ever work because the LED is connected backwards.

                              --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by gatrhumpy on Wednesday, February 16, 2011 7:38 PM

It works. I think for some reason the track it was on said FWD, but it was actually going backwards. Now the light works, and man, it's a smooth performer.

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Posted by MikeB118 on Thursday, February 17, 2011 11:15 AM

I really admire you N gauge modellers. My buddy and I model HO and have been converting Dc to DCC with Loksound decoders for some time now.

You dont have to use the loksound speaker so long as you find one with the right ampage.

the blue wire is the Common wiring when wiring lights White and blue to the front light and yellow and blue to rear light. If using same lights front and back then put resistor in blue line if lights are different and require different resistors. I wire front white light white wire with a red rear light  so that a red light appears at back when loco going forward. I wire a white light with a yellow wire to rear and a red front light to yellow wire. so that when loco in reverse a white light is on the rear and red on front.

I also wire cab lite to green auxillary so that I can control cab light separately - oh you need to insulate the front lights to stop light seepage into cab.

So to ramble on but all of above are wired to the blue common wire.

By the way I'm English so my terms might be a bit strange.

 

Good luck

Mike

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