I have an engine that runs much slower than it did on DC after DCC conversion what could affect this? It is set for max voltage and runs slow on multiple systems it is an Atlas classic Black Box and my other one is the same thing?
What do you mean, "and my other one is the same thing?" Do you have the same behavior from 2 engines?
Which decoder did you install? Did you do it yourself? Was it a new decoder, or one that was moved from another locomotive? Have any CVs been adjusted?
The first thing I would try is resetting the decoder. If that doesn't work, I'd take the shell off and check for obstructions like the decoder rubbing against a flywheel.
It takes an iron man to play with a toy iron horse.
I mean same behavior from 2 engines
Also have tried all these things you listed with multiple decoder will try obstructons again though.
Couple of things. There is some voltage drop in teh decoder so the full voltage that gets to the motor might not be as high as it is on plain DC. However, the track voltage in DCC is typically higher than 12V to in part compensate for this.
Some locos, Bachmann mostly, have capacitors across the motor as RF noise supressors which can and do have a detrimental effect when installing a decoder. Older Atlas locos shouldn't have anything of the sort but I don't have any recent production ones.
If your system supports it, make sure you are using 128 speed steps, not 28. Key example of why is seen in the recent review of the Walthers Plymouth switcher with DCC in MR. On 28 speed steps, the slowest speed it ran was like 4 SMPH. With the ONLY change being the DCC system set to 128 speed steps, NO reprogramming of the decoder, on step 1 it went less than 1 SMPH.
Finally, many DC power packs, especially with the lower loads of modern locos that don't draw nearly the power older locos did, put out well above the nominal 12V. DCC track voltage is more regulated, and does not vary much with load. How fast is 'not as fast?" Many locos run far faster than the prototype ever could at full throttle. It may not run as fast with DCC, but that doesn;t mean there is an actual problem.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Define, "much slower" with the below online speed calculator. Measure with DC loco and DCC loco.
http://www.mcr5.org/articals/speed.php
What DCC system are you using?
What speed step are uou at when you say, much slower?
I use the NCE Power Cab and my track voltage is about 13.6 vac and I see a little over twelve volts DC from the decoder as there is voltage drop like Randy said.
I never compared DC versus DCC as I researched the speed for each of my locos and run them at the prototype speeds.
I know I have seen this question here before but do not have the links.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
What is the top scale speed of the locomotives? Maybe much slower is good.
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
About half of what it was before speed wise, this is fine as it is really not much more than switching speeds but sometimes when testing track I want the process to go a bit faster.
Half? Something is definitely wrong here.
If you haven't disabled DC operation of the decoder, try the decodered loco on DC, it should be only a tiny bit slower than without the decoder installed. (if it's nto a sound decoder)
What decoders are you using? Some have a "switching mode" which cuts the speed and momentum in half. That usually requires hitting a function key to turn it on - Digitrax defaults for F6.
Do you have ANY DCC locos that run at the expected speed? Try measuring your track voltage. Even the cheap Harbor Freight meter is good enough for this, in AC volts mode. It won't be perfectly accurate but it will be in the ballpark - we should see it read 13-16 volts. If it's like 7 volts, that's not meter error because it's not designed to read DCC signals, that's a DCC system problem. Precisely half the expected is probably a blow driver in the command station/booster.
Since Randy mentioned the Harbor Freight meters, my four HF meters all read about 13.6 VAC using my NCE Power Cab. About the same at the local club that has the NCE five amp Power Pro.
The operating voltage on a couple decoders was about 12.2 vdc.
With a Scope, I saw 12 to 14 volt pulses going to the can motor in my decoder tester. The width of the pulses determined the speed.
I usually tested a decoder before installing it.
Edit.
Forgot to mention, the meter showed about 11 vdc when I maxed out the decoder settings. I don't remember what the pulse width was.
I'm bad at this - one of the first things I made when I got into DCC was a decoder tester, similar to the old Loy's Toys one. I tested exactly 1 decoder - not to test the decoder, but to see if my decoder tester worked. Since then I've even cannibalized it for parts (needed some red LEDs for something) and haven't pre-tested a single decoder. One of these days I suppose I will get a DOA one, but hasn't happened yet.
It is digitrax so that could definitely be the case