# Need for speed



## mopac (Feb 24, 2011)

Got my DCC set a few days ago and love it. Only problem I am
having is my engine has 1/2 the top speed it had on DC. It is
very noticable how slow it is. Engine is bachmann spectrum steam
with tsunami decoder. I am guessing top speed is 30 to 35 scale
mph. I am not looking for a slot car but this thing is too slow. The
drivers are short on this engine. It is for freight not for passenger
speed I know. I looked up the protype and it was built to cruise
with a train at 45 mph. I see all the time people complain cause
their DCC speed is too slow. I have that complaint also now. I also
saw where on some decoders cv5 will set max voltage. The chart on
the tsunami skips cv5 and I think I read cv5 will not accept new
values. I tried all 14 speed curves and that was no help. Anybody
else have had speed problems with a spectrum with tsunami?

If this says anything. AS I increase throttle the chug speeds up but
the train isn't going any faster. It hits top speed at 1/2 throttle or a 
little less.


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## manchesterjim (Dec 30, 2011)

mopac said:


> Anybody
> else have had speed problems with a spectrum with tsunami?


I have a Tsunami with a Spectrum diesel however I didn't experience any difference in performance vs the other DCC locos I have. And its been so long since I programmed the Tsunami, I can't even begin to try and quote it from memory.

You may want to also check the physical installation of the decoder. Did you install it or your LHS? You could possibly have some physical binding, I've had that happen once or twice when I put a shell back on and got an untied wire near a drive shaft....caused some binding.

I will say that my unscientific observation is that almost everything runs a little "slower" on DCC than they do on a pure DC system. (Not by half mind you), but there is some speed loss which I attribute believe is the nature of the beast. I have a technical theory for this...but don't want to induce a coma in anyone that might be reading this.

You might want to look at the head of the DCC section as I think that's where you'll find a chart of CV's for Digitrax and NCE decoders. This is pretty universal information for the most part (although every manufacturer has proprietary sections of CVs).

Hope you get the answers you seek.


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## NIMT (Jan 6, 2011)

Start from The basics and work your way up!
What voltage is your DCC System giving the rails check in AC voltage? 14.5 AC is normal for Digitrax.
Next why are you running it on a 14 step? 28 step is a lot smother transitions between speed steps! I don't use the Vmin Vmid Vmax, I use the speed tables to set the Decoder up.
Some cheaper DC transformers are actually over rated on output voltage in DC to make up for the use of DC and AC accessories that are in use at same time. So when you switch over to DCC some seem to notice a slow down.
Edit: And the loss that that Jim was trying to say without boring the socks off you would be the Parasitic loss of the decoder!


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## manchesterjim (Dec 30, 2011)

NIMT said:


> Edit: And the loss that that Jim was trying to say without boring the socks off you would be the Parasitic loss of the decoder!


What he said!!!:thumbsup:


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## cabledawg (Nov 30, 2010)

If your are using a Digitrax Zephyr, there is a "speed limit" setting on the throttle that will limit how fast the locos go regardless of CV settings. Because it is a starter set, it's beginner friendly so you dont break stuff by going too fast, but eliminates the need to do decoder programming. The manual has a section expalining this and it could be the culprit.


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## mopac (Feb 24, 2011)

Sean, I didn't even know I was on 14 step. I will check that. I didn't measure the volts and it is all boxed up again. I was just using my test track (small oval nailed to plywood). Its portable and I had it out. Track and wheels were cleaned.

cabledawg, its a super chief set but could still be the problem. I will look at manual again and see what I can find. 

Thanks guys.


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## mopac (Feb 24, 2011)

I went back into the manual. I found that dcs100s and dcs200s have a
potimeter inside the box that will adjust track voltage. First I will have to
establish that indeed the track voltage is low. I will use the ac reading of 14 1/2
and the manual suggested a dc reading between a or b rail and the green
ground wire on the command station, and then multiply that reading by 2.
If the readings are low then that would be my problem. Its very possible.
I do have a rms meter. What would I be looking for with it?

Got the dcc set out. Track voltage on ac is 12. It is 12 on
dc measuring from rail a to the ground terminal. So it is a 
little on the low side. I guess 2 or 3 more volts will make
some difference. Is 14 1/2 the max I should run? I did not 
see that in the manual.


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## NIMT (Jan 6, 2011)

What is the input voltage?
Check the input voltage input on DC.
Check the output Rail to Rail on AC.
If the input is too low you will not get the output to go any higher.


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## mopac (Feb 24, 2011)

Another case of operator error. I thought I had checked this. The scale switch was on 
N scale which is 12 volts on my set. HO is 15. I had already turned the volts up in the box and had 17 volts on ho. I backed it down to 15. Engine did gain some top end. Not alot but some. Enough anyway. I only have 2 dcc engines and I dug the bli sd40-2 out.
It will run way too fast, so the set is working fine. That steam with those short stubby drivers just doesn't want to run fast. Its better now and is fine with me. Thanks for the help.


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