Loss of speed with DCC. What remedy?

[ksax73]

Below is a question posted on another forum with little feedback. Hopefully it will have more useful input here.

I bought an Acela and added DCC - it's now anemic with the the speed dropping by about 1/2. The decoder is a Bachmann. Is there anything I can do to get the speed back up or can I only run in DC?

I'm having the same issue with my HHPs. Do I increase the track voltage to remedy this problem. If so, what does that do to my light bulbs, decoders, etc.? Thanks! Kyle

[ksax73]

My layout has the capability to do both. My HHPs run on DCC and they run slower than they did when they were running on DC.

[ksax73]

Two of the HHPs have Digitrax decoders and I believe one has a TCS decoder. I'm using an NCE system and under the motor control option I set the Vmax=255 and (I'm assuming CV5 is the same thing). I don't think I've ever set the Mid Voltage to that exact value but it's worth a shot. I know when I set the mid voltage to one of my HHPs around 150 or so I did get little more speed out of her but not near the maximum speeds that I am looking for. What does CV29 do?

[selector]

CV29 sets the decoder for dual power sensitivity or strictly DCC power sensitivity, and it also sets the speed table.  If you want DC and DCC capability, and the decoder is a dual-mode decoder that can operate on DC and on DCC layouts, then use a value of 38.  If you only want DCC capability, use 34 as the value in CV29. Either value enables speed steps of 28/128.

-Crandell

[ksax73]

The decoder is a DH123 decoder. I think it is dual mode decoder and if I remember correctly it has to be set to the default address of "3" in order for it to run in DC mode. I don't use this feature though so I can look at CV29 and see if making this change will help. When I mentioned that my layout has both DC and DCC capabilities I mean that the I have both a DC power pack and DCC command station wired together as if I was wiring multiple DC power packs together for multi-cab operations.

[mobilman44]

Hi!

I've only had DCC for a year, but did an awful lot of research before jumping in with both feet.  I have read and heard many times that while it is POSSIBLE to have DCC & DC on the same layout, it is a potential recipe for disaster.  I urge you to go one way or the other - preferrably DCC. 

Having been in AC (Lionel) and DC for decades, I have found them to be pretty forgiving.  DCC, however, is NOT - and just a momentary wrong connection can be very costly.

For what its worth.....

Mobilman44

[cacole]

 A friend of mine here in Arizona mis-wired his layout and was feeding both DCC and DC power to the track at the same time.  The result:  Over $500 damage to DCC components.

Two burned out CVP AD4 stationary decoders.

One burned out CVP EasyDCC Command Station

Four burned out engine sound decoders.

NEVER put both DCC and DC on the track at the same time!

 

[selector]

Absolutely, yes...no dual mode operation concurrently.  One or the other, but never both at the same time trying to energize the rails!  

And you can operate DC locos on DCC systems (some DCC systems...) using address "00".

Some DCC systems.

And the DC motors will sing and growl like you were skinning them alive when they receive the non-DC signals through the rails.

I hope you haven't damaged anything.

-Crandell

[ksax73]

NO! NO! NO! I have a selector switch for each individual track. The trains don't run DC and DCC at the same time. The toggle switches are for ONE OR THE OTHER. You'll never see a DC and DCC train running on the same exact track. On the same, TWO-TRACK main, yes, but not on the same rail. This is what I've been doing for almost 7 years with no problem. I use atlas' three position selector switches to determine which command station is controlling what track (DC or DCC). If anyone's interested, This was employed in order to make the switch over to DCC more gradual and easier on my wallet. It also serves (and most recently did) as a back-up in case a decoder malfunctioned on a particular engine I wanted to run and I had no immediate replacement. Case in point; on my layout, it is IMPOSSIBLE to feed both DC and DCC to the same track. That's how I designed it (with that in mind).

[Vail and Southwestern RR]

If you are powering the layout with both DC and DCC at the same time, and it is possible for a loco to pass from one to the other, you could potentially have trouble when someone isn't paying attention.  If I was going to do it, I would wire it to insure a dead block between a DC and DCC section.  By the time I went to that much trouble, I would just go either/or, and not run both at the same time!  But, it's your risk to take.

[ksax73]

Try to not think of it as using both power packs to provide power to the layout and two train on the same exact train using two different sources of power (that's the sense I'm getting from some of the posts). It's impossible for both packs to be feeding the same track at the same time on my layout. If there was a way I could quickly draw up a sketch of the wiring diagram I'd post it. Fortunately, It's EXTREMELY rare these days that I would run a DC engine on one track and DCC on the other anyway and if one would cross into the other, I'd have a collision (something that I do not necessarily aim for in my operations, lol) because the switches on the one-and-only interlocking on the mainline was incorrectly thrown. There are two parallel mainline tracks that are electrically isolated from each other. There are no blocks along the same track that are selectable so there's no way a DC and DCC train could collide on the same track. The only collison possible is if a switch was thrown improperly. Most simultaneous operations (which are also rare on my layout) involve two DCC locomotives at the same time with no DC power turned on. I have far more DCC locomotives than I do DC locomotives at these days (especially with my growing obsession with sound). The only trains that I still run on DC on a somewhat regular basis is my Acela (for reasons explained earlier in the thread) and my Atlas ALP44 (collecting dust). 80/90% of my AEM7 are DCC, all of my frequently used diesels use DCC and most new equipment coming in has a pre-installed decoder. In even more rare cases (and I don't like doing this anyway), if I have to switch a DCC engine in front of a DC engine (thus switching both mainline tracks to DCC via a 3-position toggle switch) the other train would have to come to a complete stop in order to 1-avoid a collision and 2-cut power to the track. Of course this scenario leaves the DC motor buzzing for a few seconds (which is why I avoid this when possible). Fortunately/Unfortunately, the layout is too small for one to loose track of which train is where.

[maxman]

May I make an uneducated person's suggestion?

What I would do is put one of the engines you are having a problem with on your programming track.  Then use the "use programming track" option on your NCE system to get to the screen where you can set the CVs.  Set CV 8 to a value of 8.  As I understand the Digitrax instructions this should reset your decoder to the original default values, including the address to 3.

Remove the engine from the programming track and try running it on your DCC main with address 3.  If it runs on address 3, you have (hopefully) reset it.  Now put it back on the programming track and, when you get to the different programming options, chose the one that I think says "standard programming".  There you can change the long address to whatever you want as well as changing the "normal" direction of travel if necessary.  Since you have the NCE system, one of the programming options that you will see is the ability to have the engine run on analog as well as DCC, or DCC only.  I think the default option is DCC only, but make sure you select this if it isn't.  DO NOT ENTER the motor control option, or anything else at this point.  What I'd do here is just get out of the programming mode and try running the engine.

Because you have the NCE system, there is no need to worry about CV 29 as all that has been taken care of by the programming.

Now, when you try running that engine, the decoder should allow you to apply the full available voltage to the motor when you select the maximum speed step. And because you have reset the decoder to the default values, you shouldn't have to worry about any mistakes you might have made if you fooled with CV 2, CV 5, or CV 6 (Vstart, Vhigh, and Vmid).

With full available voltage to the motor, that's as fast as the engine will go.  And this should be the same speed as what it would have moved if running on DC without the decoder.

(Note that the engine will now not run on DC because you disabled this option with the programming.  Also note that I've assumed that the Digitrax decoder has the Vmax default value set to give maximum voltage.)

Hope this works for you.

Regards