My lovely wife, whom I do not deserve, got me a Prodigy Advance for Christmas.
I’ve successfully installed a few decoders, and have been pretty happy with
the unit. But I’ve got a few questions that I can’t figure out.
I was also given an MRC synchronized steam decoder, which I’ve installed in a P2K 2-8-4. It’s not bad (certainly for someone who hasn’t had sound in HO before), but I can’t get it to run slowly. On DC power, the big beast would just creep along as slow as you please. I’ve tried to properly adjust the starting voltage CV, but I can’t get it to crawl. Am I missing something here? Is this just not a great decoder? I’m certainly not thrilled with the level of documentation with the MRC decoders - the digitrax and NCE decoders I’ve installed certainly seemed more helpful.
And a second question, which is, perhaps, more … silly?
I had figured (perhaps incorrectly) that one of the ‘features’ of DCC was that the throttle was augmented with acceleration and deceleration effects, and that the engineer would hit the breaks as appropriate. Well, there’s a nice red ‘STOP’ button on my Prodigy throttle, but it’s a bit drastic. Were my expectations out of whack? Please don’t tell me that the Prodigy isn’t a good system - that would be too hard to hear at this point!
The “nice red ‘STOP’ button” on the throttle is for emergency stops. It’s purpose is to shut down your DCC system in the event of (and to avoid) a major catastrope like a train wreck. You should use your throttle knob to slow down and stop your trains.
Charles, you also have to adjust your CVs (or configuration variables) to change your momentum and deceleration settings. Your decoder may be set at “28”. For a more elongated acceleration and deceleration, you will need to change the CV setting (that alters that specific function) to a higher number, like 128.
tstage is right. It’s for emergency stops. Set you throttle to zero to do a normal stop. On a sound equiped loco a rapid stop should also cause a brake squel sound. (or at least mine do) You can also adjust the speed at which a loco will slow down by adjusting the decel CV which is the fourth value you can enter when programming a loco. (I also have PA) I cant comment on the MRC decoder since I dont have any. You could try moving it to another loco and see if the problem follows the decoder.
Randy Rinker will likely speak up here before long, and if I am right, he feels that some of the MRC decoders are not up to snuff. Several others seem to fell negatively about them, too.
There should be a manual for the decoder you have. Download if from the site, if you can. Then, find how to program CV 2 for the V-Start that will work best for you loco, and also CV’s 3 and 4. Typically, a value in 3 and 4 should be near 120 if the value range for that decoder is between 0 and 255…like most of the better decoders nowadays.
Have you found a way to get four chuffs per driver revolution? If that doesn’t work, then you need to find, again in the manual, the CV that controls chuff rate. Usually you must program CV 49 to a value of 12, or whatever they say, and then CV 52 to a value between 0 and 255…if I remember correctly. The lower the value, the slower the chuff…I think…it has been a while.
Point is, your decoder may not be particularly user-friendly, or else you are not programming either the right CV’s, or programming them using the right method and they are not retaining the input values.
Addendum - I forgot to address the brakes question. My QSI decoders permit activation of squeel using F 7. Pressing it while the locos speed is constant or accelerating yields flange squeel, but if you reduce the throttle setting to 0 in order to get the loco to stop, it will activate brake squeel, BUT… it will also rein the loco in within two seconds…no deceleration according to the CV 4 input. So, “Emergency” is immediate stop for that purpose, and F 7 while the loco is slowing will mean brake squeel, hiss, and very quick stop. My Tsunami does not do any of this.
The deficiency in the MRC decoders is in the motor drive. The power portion of an MRC Tech II or newer DC power pack is better for low speed motor control than that on a decoder lacking features like Back-EMF and load compensation. These things are called various names by the different manufacturers, but I’m pretty sure the MRC decoders have none of these - they might not even have high-frequency motor drives.
Only a few decoders implement a brake function - QSI , Soundtraxx, and ESU Loksound are a few. This works in conjunction with the deceleration rate CV - most decoders have this, there’s also an aceleration rate CV. So you can set up your loco to come to a stop faster than it speeds up, or vice versa. I’m kind of suprised the Tsunami doesn’t have this function, as the DSD-100LC I have seems to have it. Or maybe it doesn’t really stop the loco, I don’t have a motor hooked to it and never will, I only bougth it for the sound portion.
As has been stated, the STOP button is an emergency stop. On some systems it is configurable to either stop just your train (the loco currently selected on the throttle) or shut down the entire layout. Useful to prevent those Gomez Addams moments.
Yes, I had actually figured that the ‘STOP’ was emergency stop! I guess that I had been thinking that the the deceleration configuration was to mimic a train gliding to a stop under no power, rather than active brake application. But I guess that makes sense.
Selector - thanks for the detailed info. MRC’s synchronized steam deocder must be oneof the older ones, then, as the ranges for those values are between 0-32. I’d already found that they seemed realistic set around halfway or so. And I did manage to find
the configuration for the steam chuff synchronization. That much works pretty well.
I guess as my next step I’ll try setting the speed steps to 128 and playing with it from there. Thanks for your help!
Randy, I apologize, but I was not very clear about the Tsunami. The emergency function works, as do the CV’s 3 and 4, but I have not been able to get it to do a “quick” stop on F 7, as do the others.
That’s what I meant, I assumed the emergency stop works, that’s not necessarily controlled by the decoder anyway. Maybe the Tsunami diesel version will have operating dynamics - since steam locos don’t have dynamic brakes anyway. Like I said, I dunno if the dynamic brakes actually STOPS a DSD-100LC like the QSI, so maybe Soundtraxx doesn’t offer this function in the same way.
I’ve always wanted to have real brakes on a train - build a loco with a large flywheel and a free-wheeling drive, either a clutch or a spur gear or a properly pitched worm. In a caboose, a very low powered motor that freely turns when pushed - ie no more drag than one of those Proto2000 lighted cabooses. ‘brakes’ applies power to the motor in the caboose in the opposite direction of movement. Might run away down grades though, not enough braking force. Might be able to simulate botht he free-rolling drive and high (energy) density flywheel by having a second motor in the loco that acts in concert with the main motor. Slowing this motor could be the independent and/or dynamic brakes in the loco.
Some day…