Trains.com

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

NCE DA-SR LED's resistors and traces

2547 views
10 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Wednesday, August 10, 2016 10:26 AM

 Want to be sure, use a meter with some good quality small pointy probes (some of the cheap ones MIGHT break your skin if you jammed them in really hard, others, like most Fluke probes, are almost as sharp as a hobby knife) set on ohms, and measure across the resistor whose jumper you are cutting. If you get 0 ohms or close to it, the trace isn't cut enough. You should get somethign near the value marked on the resistor. Based on the picture in the instruction sheet, they are 1K (102). For once this is actually a decent value, many others with built in resistors use 560 or 680 ohms, which usually makes for a very bright LED.

 Since resistors are pennies a piece, it may make sense to just leave the trace and use an external resistor on each LED.

                         --Randy

 


Modeling the Reading Railroad in the 1950's

 

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

  • Member since
    December 2001
  • 1,932 posts
Posted by Stevert on Wednesday, August 10, 2016 7:54 AM

A word to the wise:  If you decide to cut the trace instead of using an external resistor, make sure you really cut the trace!

I bought a four-pack of DA-SR's a while back.  Put one in and cut the trace per the instructions.  Headlight LED exploded when I first turned it on. 

Hmm, apparently I didn't cut the trace well enough.  Grab the Exacto and make a few more passes over my previous cut.  Replace the headlight LED, which then proceeds to explode when I turn it on.

Now I'm ticked.  Grab the Dremel with a fine burr.  Remove the trace entirely.  Repeat for the rear light.  Now there are grooves in the PCB where the traces used to be.  Replace the LED yet again, which (thankfully) doesn't explode this time.

Threw the other three DA-SR's in the drawer, where they remain to this day.  Used TCS A6X's with built-in regulated 1.5v power for my next conversions.

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Wednesday, August 10, 2016 5:58 AM

mlehman

Yep, they do. You don't always have the manual with the decoder later. The internet pulls up old and newer documentation. Sometimes you need to do a little investigative work to nail down what version of a decoder you have. All in a day's work in DCC land.

 

 

 

Although, in this case, the OP already has the manual.

Here is a link to the NCE site. The manual is a PDF, linked at the bottom of the page for those who are curious.

https://ncedcc.zendesk.com/hc/en-us/articles/201382145-DA-SR

Rich

Alton Junction

  • Member since
    September 2003
  • 10,582 posts
Posted by mlehman on Wednesday, August 10, 2016 2:44 AM

Yep, they do. You don't always have the manual with the decoder later. The internet pulls up old and newer documentation. Sometimes you need to do a little investigative work to nail down what version of a decoder you have. All in a day's work in DCC land.

 

 

Mike Lehman

Urbana, IL

  • Member since
    March 2015
  • 1,358 posts
Posted by SouthPenn on Tuesday, August 9, 2016 10:45 PM

Don't a set of instructions come with the decoder?? 

 

South Penn
  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Tuesday, August 9, 2016 6:09 PM

BigDaddy

Thanks guys, other manufacturers directions that I have read make it clear it is an either or, NCE was not clear, at least to me.  The manual page on the website, does say it's for old and achived manuals.  The don't bother to alphabetize the list and there seem to be 3 links to DA-SR manuals, one of which is the 2003 version.

 

Henry, you are correct, the NCE manual is not clear. In fact, it is almost contradictory.

I have several of the older DA-SR decoders, and those older ones were problematic.  I had a few that fried for no apparent reason and a couple where the function outputs burned out. Hopefully, the new version is more reliable.

Rich

Alton Junction

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 9,094 posts
Posted by BigDaddy on Tuesday, August 9, 2016 6:05 PM

Thanks guys, other manufacturers directions that I have read make it clear it is an either or, NCE was not clear, at least to me.  The manual page on the website, does say it's for old and achived manuals.  The don't bother to alphabetize the list and there seem to be 3 links to DA-SR manuals, one of which is the 2003 version.

Henry

COB Potomac & Northern

Shenandoah Valley

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Tuesday, August 9, 2016 5:45 PM

You can use your own resistor or cut the trace and use the built-in resistor, but don't do both. It is meant to be one or the other, not both.

Rich

Alton Junction

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Tuesday, August 9, 2016 4:07 PM

 Ouch, and people complain about Digitrax's web site? If you go to the manuals section on the NCE page and find the DA-SR, you get the old manual from 2003 which says nothing about built in resistors, the version from 2003 didn't have them. But if you go to the product page and click the link that says "DA-SR solder pads" you get the 2006 version of the manual, in which the decoder now has built in resistor.

                            --Randy

 


Modeling the Reading Railroad in the 1950's

 

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

  • Member since
    September 2003
  • 10,582 posts
Posted by mlehman on Tuesday, August 9, 2016 2:19 PM

Henry,

It's your choice which to use. I like custom resistance levels higher than typically found with the recommended 1k ohm value, because that's usually too birght for my tastes.

But using a LED with the specified output is easy, you cut the trace that otherwise bypasses the built-in resistors. try it and see, you can always add more resistance if too bright.

Mike Lehman

Urbana, IL

  • Member since
    December 2015
  • From: Shenandoah Valley
  • 9,094 posts
NCE DA-SR LED's resistors and traces
Posted by BigDaddy on Tuesday, August 9, 2016 2:11 PM

I'm about to do my first DCC conversion.  The directions recommend a 1/4 watt 1K resistor.  The next paragraph says there is a built in resistor and a trace that should be cut if you wish to use LED's.

Am I supposed to use one or the other or both? 

It's an HO Atlas RS1 if that makes a difference.

Henry

COB Potomac & Northern

Shenandoah Valley

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!