ran a non-DCC loco on NCE PHR system

[rrinker]

 The old Soundtraxx LC decoders did not support running on DC in any form. Worse than not supporting it, they were damaged by DC. When you use address 00 to run an analog loco you are essentially putting a DC component in the DCC signal, so I would expect an LC decoder to not like it. Those are some of the only decoders that had that issue.

                                      --Randy

 

[Oakhurst Railroad Engineer]

I just switched from DC to a DCC Digitrax Super Chief 5 amp.  I sill have 7 DC locomotives of various types and have been running them with no problem ... except last night ...

I was running my old Rivarossi Heisler, which is a poor runner in DC that sometimes just won't run at all. It was doing great on DCC (address 00 ).  Both lights (front and back) we on constantly.  Then all of a sudden, when the loco was stopped (and singing), a smoke plume came up from the cab.  I could see a bright glow from inside, to match the brightness of the light.  Apparently I was running too much current through the light wires.  I turned it off and on (using the old block switches still installed) and each time the smoke plume reappeared.  I decided it was best to permanently retire it from use.

Other than that, the old DC locomotives (Roundhouse Shays and Climax & Bachmann Shays) work well.  I can use the old block switches to turn off the power as the "singing" can get annoying if they are just parked.

The Digitrax AR1 reverser on the Wye works perfectly for my DCC locomotive, and sometimes works for the DC locomotives. Can't really get it adjusted to work for the Bachmann DC Shays and sometimes I have to trip it twice to get it to work for the other DC locos.  Still I have reasonable DC loco layout function while I work to get most of them converted to DCC over the next few months.

Marty 

[CSX Robert]

rrinker

The old Soundtraxx LC decoders did not support running on DC in any form. Worse than not supporting it, they were damaged by DC.

I have heard that the Soundtraxx LC decoders would be damaged by DC, but I have not been convinced that that is true. All decoders actually operate off of DC that is rectified from the DCC signal, so I don't see anyway that feeding DC power to a decoder can damage it as long as the voltage is not too high.

Those LC decoders were also very sensitive to over voltage, and I suspect some people may have tried to run them on DC and turned the power up too high exposing them to too much voltage, resulting in blown decoders that they subsequently blamed on DC. Something else that may have contributed is the fact that if the DC has any AC ripple in it(which most power packs that I have used do), the rectified and filtered DC on the decoder will be higher than the measured DC output of the power pack(one of the reasons decoder manufacturers say their decoders will run on "smooth" DC).

[Stevert]

rrinker

 When you use address 00 to run an analog loco you are essentially putting a DC component in the DCC signal, so I would expect an LC decoder to not like it. Those are some of the only decoders that had that issue.

                                      --Randy

  You're really only increasing the duration of either the negative or positive sides of the zero bits.  In other words, all you're altering is the timing.  There isn't really any higher voltage, or DC voltage being superimposed on the DCC signal. 

But I didn't know that the LC's were sensitive to zero-stretching.  I guess then that I'm not surprised Soundtraxx called those decoders "Low Cost", if they're designed so cheaply they can't even deal with it.  They do sound good, though, at least the one I have does.

(Note to self:  Add this to the list of reasons to NOT use zero-stretching on your Super Chief...)

Steve

[richg1998]

 I experimented with a LC decoder up to 12 volts DC and there was no damage. Someone in another forums asked the same question. No, the decoder does not respond to DC. I did not try any higher than 12 volts DC.

The LC decoder like all decoders picks off the DCC signal just before the bridge rectifier and sends it to the microprocessor IC but the IC does not have any code to recognize this. Dual mode decoder have code to handle the DC voltage and recognize that there are no DCC pulses present.

Rich

[Vail and Southwestern RR]

Stevert

You're really only increasing the duration of either the negative or positive sides of the zero bits.  In other words, all you're altering is the timing.  There isn't really any higher voltage, or DC voltage being superimposed on the DCC signal.

It's picking nits, but I'd have to disagree with that. Changing the length of the pulses definitely adds a DC component to the voltage. There's no other way an analog loco would move. Now, it's not really a DC voltage added to the DCC signal, as the levels of the voltages don't change. But the average voltage on the rails is no longer zero, hence there is a DC voltage present.

[locoi1sa]

Stevert

But I didn't know that the LC's were sensitive to zero-stretching.  I guess then that I'm not surprised Soundtraxx called those decoders "Low Cost", if they're designed so cheaply they can't even deal with it.  They do sound good, though, at least the one I have does.

 

  Sensitive is not the word I would use. The LC280 decoder that fried acted strange before it failed. The loco was pulling a small train when it just stopped and started vibrating and the drivers were going from forward to reverse in only an inch of track. I did not know someone was running 00 at the time. I figured it was a dead spot or dirty wheels that made the train stop and did not see the drivers going nuts. I pushed on the caboose to see if it would go again. No go so I went to the loco to see what was up and saw the drivers going nuts. Just before I picked it off the rails it stopped and was fine for about 10 feet. Then it started freaking out again. I picked it from the rails and I smelt a burning plastic smell. The loco was a Spectrum 4-8-2 that previously had a TCS non sound decoder. I clipped the caps from the Spectrum board when the TCS decoder was in it. I changed out the LC280 decoder with a non sound decoder and the loco runs just as good as it did before. I gave the LC280 decoder to an electronics engineer (my x brother in law) to see if he could fix it for me. That was 3 years ago.

      Pete

[richg1998]

 Stretched zero bit info. Plus how decoders really operate.

http://jdb.psu.edu/nmra/faq_19.html

http://members.shaw.ca/sask.rail/dcc/DCC-waveforms/DCC_waveforms.html

http://www.loystoys.com/info/how-dcc-works.html

Rich

 

[pastorbob]

In the 1980's I used a pre DCC system called Dynatrol which had decoders also.  They wired in the same way, but I had a limited number of "channels" to use, so I would build consists using locos that had the same channel number, I had duplicate channel numbers and managed the fleet so I never had any unexpected surprises.

In 1999, as Dynatrol was dying, the founder, Abbott Lathi (sp) started manufacturing dual decoders that would support System One/NCE or Dynatrol.  Seeing the future I started putting the new decoders in locos, then knowing I was going to switch to NCE, I put NCE decoders in all the rest.  When I cut over in 2000, no wiring had to be replaced, I just replaced the Dynatrol with an NCE command station and four boosters.  The engines with the dual decoders sensed the change to NCE and ran fine.  I still have 4 or 5 diesels with those old decoders.  The rest have all been upgraded, and all new power have NCE decoders.  My diesel fleet is just over 300 engines.

I knew from the gitgo that I should not/would not run DC diesels on NCE, and since I had already changed over that was not a problem.  The fleet number was considerably less in 2000 than today.  I also was advised by NCE from the gitgo that I should not try to run DC locos on the system.  I never did, I never burnt out a loco.

I run on many different layouts with many different DCC  systems, and would still stay with NCE over the rest.

Bob