starting voltage

[brubakes]

My 1st and only DCC locomotive is a Bachmann 2-8-4 Berkshire. It takes moving the speed setting up to around 14 before the locomotive will move at all. When I have six cars behind it it takes up to around 20 to get it moving and even then its pretty slow. On the 0 to 28 speed scale this seems to kind of stink.

My questions is about starting voltage. I thougth I read in some book (which I cannot find) about setting the starting voltage for the locomotive. So that 1 would be more like a 14 or something along those lines. Is this what starting voltage is for? If so how do I go about programming this? (NCE Power Cab)

 

[HaggisKennedy]

Yes. That's basically what it does.

Starting voltage is CV2. Set it to 14 and see what happens. If it's still bad, you can jump it up to 20 or whatever. I've had some Athearns set at 40 before they start to creep.

As far as ss20 with cars, that might be normal, since you are now pulling the weight of the cars. You may not expect the same starting setting with a train vs just the loco itself.

What I do is see where a loco starts, then jump in and set CV2 to something like 20-25. If the loco starts moving fast at ss1, then I adjust it downwards. I usually adjust in increments of 5, and fine tune from there.

The other thing you might consider is that new locos are 'tight'. If a loco is run awhile, it can be 'broken in', which means the mechanisms are 'loosened'. That would decrease the amount of voltage needed to start the loco.

Which is a good reason to have either a test track loop somewhere, or make sure the layout is a roundy-round.

Kennedy

 

[brubakes]

How long does it normally take a loco to break in? I have a small single line main 10' x 20' layout.

 

[brubakes]

How does one go about setting that CV2?

 

[Selector]

First, you need a DCC controlling system. Then, with the layout powered, you select the locomotive you wish to fiddle with. Then, with that decoder active on the throttle, you enter Ops Mode programming, or what is called "programming on the main". Making good and sure you really are in Ops and not in Paged Mode, you dial in CV 2, and then do a series of trials to see which start voltage works for a given motor. Start with 20, then go up or down, and follow the best indication of movement at a speed step of "1".

So, after programming a given input, exit programming and dial up the first speed step. Nothing after three or four seconds? Re-enter programming, leaving the speed step at "1", and keep bracketing your initial figure until you find the one that just barely gets the loco underway.

Note! New and cold engines take more voltage to get underway. An engine that has been in use for a while, and certainly one that is warmed-up and has been used within the past few minutes, will take less voltage to get underway...in my experience. So, don't be surprised to find that your carefully detected setting in CV 2 doesn't always yield the same results.

 

[brubakes]

just to clarify this is done on a per loco situation right?

 

[brubakes]

Is this a standard feature for DCC equiped locomotives or do I have to verify the loco in question supports this?

 

[Selector]

If the decoder is NMRA compliant, yes. Although, it never hurts to download the manual and have a check.

Basically, the way it works for the vast majority of them, CV1 is for the address of your decoder (you give it a "name" and it will answer to that name, and no other). If you assign it "06", often because it's the engine number painted on the running boards or on the side of the cab below the window, it won't do anything unless you acquire "06" on your throttle first. Otherwise, it sits doing what it was last instructed to do.

CV2 is for the start voltage. CV3 is for inertia...getting a train underway from a standing start. CV4 is for momentum...the train takes a few hundred scale yards to screech to a stop. And so on.

Yes, each decoder has to run an individual engine, and engines vary. So, the decoder needs instructions about how to make the engine behave like a scale model of the real thing should. That must be done as individually as if you were teaching a child. However, when you use Ops Mode programming, only the engine (decoder) actively engaged on the throttle will accept the CV changes you programme. The other engines will simply look the other way because you haven't identified them as the ones being subjected to the programming. You can do that by using Paged or Broadcast Mode, but heaven help you if you make a mistake and only wanted to change one CV in one decoder, but do it in Page Mode by mistake. And....you will. At least once. Which means you will have to deprogramme that change, still in Paged Mode so that they all do it in one batch, and then you do it to the right engine in Ops Mode. Trouble is, what setting will you use when you reset them all? Was each decoder set with the same value input for the CV you just changed? Chances are no. So you will really have to go back and reprogramme each one with the correct value...so keep notes for each engine.

 

[brubakes]

Lucky for me I only have 1 DCC Locomotive at the moment, so when I screw it up, which I did, it was pretty easy to correct. I'm not back to where I started at with the loco. Gonna retry starting voltage again tonight.

 

[HaggisKennedy]

I usually run a new loco about 1/2hr, 15min each way, forward and reverse. You want to make sure the trucks swivel in all directions (if you have a slope).

A lot of it has to do with seating the commutators in the motor.

Kennedy

 

[CanuckMark]

Just to clarify, the Start Voltage value you assign to CV2 doesn't correlate to the throttle speed number (aka 0 to 28), it actually is a value from 0 to 255. So if the loco currently starts moving at 14 putting 14 in CV2 probably won't be the ideal value. You'll probably be up in the 40ish range, maybe higher. Once a new start value is entered to CV2, the decoder automatically re-maps the 28 throttle speed steps starting at the new CV2 value. You can also set a new "mid" value (CV6) and a top speed/"max" value (CV5) too if you like.

As has been mentioned before, programming that value on the main is the best way to do it since you can set it on the fly. Set it with just the engine (no cars) on a level stretch of track. With the throttle at 0, put 40 into CV2. Move the throttle to 1 - if it starts moving quickly, reduce CV2 to maybe 35 then try again. Keep changing it until the loco doesn't start moving on its own from 0 to 1, but maybe starts moving slowly at 2 or 3. When you then turn the throttle down to 1, it should still be just barely moving.

As the engine breaks in you can set a new value to CV2 anytime to adjust.

Mark

 

[brubakes]

Okay, well aparentlly I'm just too stupid to figure this out. I go into prog, it says program on main i hit enter. the screen says "ops prog" and asks for the loco number, i enter the loco's number and hit enter. next i hit 2 for CV. asks me what CV num. I say 2 and hit enter. It asks for a value. Enter 40 and hit enter. Back to the orginal screen. Hit the throttle and I still am right where I was.

 

[Selector]

Okay, well aparentlly I'm just too stupid to figure this out. I go into prog, it says program on main i hit enter. the screen says "ops prog" and asks for the loco number, i enter the loco's number and hit enter. next i hit 2 for CV. asks me what CV num. I say 2 and hit enter. It asks for a value. Enter 40 and hit enter. Back to the orginal screen. Hit the throttle and I still am right where I was.

What are the steps that you are to take according to the manual?

I don't see why you're being "kicked back" to the operational screen. That is certainly not what happens with Digitrax's DT 400. In my case I must press an exit key in order to return to regular operations.

 

[CanuckMark]

If the engine took the new value it should have surged forward for a fraction of a second (it's like an acknowledgement signal) - just a quick little jump. If not, it didn't recieve the command.

You may also want to try a number higher than 40. I have an old Athearn that had to go up into the 60s and 70s before it started responding. But, on the other hand, you should at least see some difference with 40.

Does that controller have a way to read the CV from the engine?

Mark

 

[brubakes]

Does that controller have a way to read the CV from the engine?

Yes it would seem it does. In fact it even shows a vaule i have put in there. However, it seems whenever I make that change the loco stops working.

 

[HaggisKennedy]

If it's a really tight loco, then 40 may not do it. The next step would be to jump to, say, 60, and see what happens. If you get up to 80-90 and nothing happens, then the new values aren't taking.

Kennedy

 

[brubakes]

Can I program just CV2 and leave all the others the factory defaults? It seems when I do this the loco just stops working.

 

[brubakes]

Here is what I have been doing...

1. Set speed to 1
2. Hit Prog/Esc key 4 times
3. Use Program Trk is displayed and I hit enter
4. Hit 2 to enter a CV number
5. Tell it CV 2 and hit enter
6. Tells me to "Wait" while it sees the loco and tells me what the CV2 value currentlly is.
7. Then asks for a value and I entered 50 (to start, already tried a few others)
8. hit enter to set said value
9. Prog/Esc to return to the normal operating screen

Everything should be good at this point right? Naw... same as if it was a full factory value.

Below is taken diretlly from the NCE Power Cab manual on setting starting voltage.

A good way to setup the Start Voltage is to first set your throttle to speed 1 then go
into this Start Voltage programming and try different values until you get the desired
starting speed. This approach can be used with most of the motor speed
adjustments. You may exit programming at any time by pressing PROG/ESC.

 

[Selector]

I know this is very frustrating and almost painful for you, so we'll keep trying to get this solved.

First, I don't know why you would feel you have to press prog/esc four times. Is this what the instructions say to do? Sounds very odd to me.

Secondly, I would never use a programming track for setting any CV except for the CV1 addressing. I do all other programming on the main in Ops Mode. The display message you relate to us suggests you are programming in Paged Mode, and your decoder may not accept such programming...some decoders need a special resistor or booster to programme on a programming track if the base station is set for Paged Mode programming. I may be steering you wrong and confusing you, but does your manual mention the various programming modes? You want Ops or Main programming.

Hitting 2 to tell it to take a CV change and then inputting 2 sounds funny to me. As you describe the sequence, you should see "22" on your screen.

If you are doing all it says to do and the engine still takes off as soon as you give it any voltage, something is not taking.

We have done a full reset...and the proof was that it will only respond and move (repeat, and move) in address "03", is this correct? If so, you are doing something wrong in the programming or your system doesn't work, or the decoder is defective.

It sounds like you need to call the tech folks at either NCE or call the decoder guys and ask them to talk you through a couple of tests. They are usually quite helpful.

 

[brubakes]

Hitting 2 to tell it to take a CV change and then inputting 2 sounds funny to me. As you describe the sequence, you should see "22" on your screen.

There is a sub menu between the two 2s. The first 2 chooses that I want to program a CV. The second 2 is me telling the cab what CV it is I want to program.

We have done a full reset...and the proof was that it will only respond and move (repeat, and move) in address "03", is this correct? If so, you are doing something wrong in the programming or your system doesn't work, or the decoder is defective.

I can do a recovery on the decoder in question and reset it all to default. Which is nice for when I mess up. I've had to do this a few times. The 1st thing I do is go through the quick start guide that came with my cab which basically lets me set the short and long addressed of this loco. 59 and 759 in this case.