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Issues with programming Digitrax Function Only decoders

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  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Sunday, March 4, 2018 4:46 PM

 Load the track with a resistor - loading it with those bulbs is far too much load. An 1157 bulb is somewhere just north of 2.5 amps. Even with a program track booster, there's not that much current on the program track.

 The DCC standards specify not more than 250ma on the program track, and the ack pulse from the decodr should be 60ma minimum. On a function decoder where the functions are limited to 50ma, you're not going to get a full 50ma load. a 1K or slightly under resistor will add anouther 9-10ma and bump it over.

 Actually the TL4 and TF1 instructions say the function output(s) are good for 125ma each, so you can certainly contrive a load for programming - a 150 ohm 1 watt resistor would pull 80ma. 1 watt would be the bare minimum - I^2R give.96 watt! 

 Of course, the instructions make no mention of needing a load on the function output for it to program - and they also do not program in Ops Mode, so forget about that.

 You will note I have mentioned several times, I love my Digitrax DCC system but I won't use any of their decoders. TCS and ESU ones are just infinitely superior. Stick with the TCS FL series. They even say right in the instructions to connect a 50-100 ohm resistor between the blue and any function wire for readback on the program track. 

 I do find it funny that TCS does the same thing Digitrax does - puts some basic setup information in the sheet that comes with the decoder, but refers you to the seperate "comprehensive guide" to learn ALL the features. But no one ever complains about TCS doing this. If you've never looked at that book (free download on the TCS web site), take a look - it's amazing the array of adjustments and features even their more basic motor-only decoders actually have.

 

                            --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
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Sunday, March 4, 2018 2:43 PM

Randy
 
Load the track or the decoder with the resistor?  Loading the track hasn’t work for me.
 
 
 
Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951
  
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Sunday, March 4, 2018 2:28 PM

 Yes, the decoder needs a load to be able to do a read back on the program track. Most motor decoders need something connected to the motor terminals to work properly as well.

 Try a 1K resistor across the program track, the ack pulse doesn't need much, and a 1K resistor seems to be plenty to help most decoders that need a little help, like the cheapy Bachmann motor only ones.

                                --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
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Sunday, March 4, 2018 2:09 PM

I guess I misunderstood where to put the load.  I tried loading the track.  Do I need a 50ma or so load on the function out put?
 
EDIT
 
The load on the TL1 is 38ma.  It trips a 5 volt relay with a pair of 470Ω resistors parralled in series with the relay.  I shunted the relay coil with a 1N4000 to protect the decoder.
 
 
Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951
  
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Sunday, March 4, 2018 1:57 PM

 Well those bulbs draw too much current. Probably won;t hurt anything ont he program track (but probably won't work, either), but if you tried to turn on a function output on the main with one of those hooked up it would fry the decoder.

                                              --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
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Sunday, March 4, 2018 12:07 PM

Randy
 
I tried it using a 3157/1137 dual filament automotive bulb, my standard load.
 
 
 
I tried both filaments one at a time without any success on both modes, Prodigy alone and Decoder Pro driving the Prodigy.  After dozens and dozens of attempts over about three hours I finally got both decoders working.  Unless one is broke I’m definitely not going to try and fix it!
 
 
 
Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951
  
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Sunday, March 4, 2018 10:55 AM

 It's lack of sufficient load for the ack pulse on the program track. They might work with a light bulb, bit with an LED, not much of a chance. 

 Just use Ops Mode. JMRI will still save the settings you pick, even if it can't read from the decoder. Just make sure you have no other loco with the same address on the track at the same time.

                                     --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
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Issues with programming Digitrax Function Only decoders
Posted by RR_Mel on Saturday, March 3, 2018 9:55 PM

I haven’t experienced any problems programming decoders until I got the Digitrax TL1 and TF4 function only decoders.
 
My DCC operating system is a MRC Prodigy Advance².  I also have the MRC computer interface cable.  Since Randy walked me through programming using Decoder Pro every decoder has worked correctly the first time until now.
 
Decoder Pro stalls and comes back with errors and when I do get it to work it takes 5 or 6 times to change the address.  It will not change CV 61 or 64.
 
My Prodigy won’t change the address on either the TL1 and TF4 but it will work on CV 61 and 64 first try.
 
After many hours I have both decoders working the way I want so I’m a happy camper but I would like to know if it’s me or a Digitrax problem.  I have five other regular Digitrax decoders with and without sound and all program easily first try.
 
 
 
 
 
Mel
 
Modeling the early to mid 1950s SP in HO scale since 1951
  
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 

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