Large Scale Central

Aristo-Craft Crest Switching Power NOT OK with Sierra Sound?

General Discussion
#1

Hopefully TOC will have an analysis or those who use the Crest Switching Power supply with a Crest 10 amp Power Controller.

PROBLEM:
Apparently the Crest system influences the excellent Sierra sound system in my USA diesel (“dismal”) to continuously make the horn sound — repeatedly without pause. A conventional LGB powerpack, when connected to the same test track, activates the loco’s sound only IF there is a change in power setting.

MY GUESS: The Aristo system has some sort of “pulsating” power and therefore there is a continual up-and-down slight power change thus activating the horn sound.
Is this cause accurate?

REMEDY?
Either way, is the cause in the controller? In the power supply itself?
I am changing out the power supply and bought (stupidly?) the Aristo system.

Appreciate your insights.

Thanks,

Wendell

#2

<MY GUESS: The Aristo system has some sort of “pulsating” power and therefore there is a continual up-and-down slight power change thus activating the horn sound.
Is this cause accurate?>

Prolly an excellent guess. I have seen this happen before. 'Speshully with an Aristo TE receiver set to “Pulse”.

To remedy, you might want to program the Sierra to sound the horn and bell with a reed contact, instead of power fluctuations.

But I’m sure The Old One has better info.

j

#3

Well, I guess this is the way to get Wendell to call me…

Horn Sensitivity (step 17) and Filter Rate (step 18) will compensate for voltage fluctuations.

Can be done from the external valume control (provided with every unit I sell at no cost).

I walked Wendell through the steps.

He will try and report back…

TOC

#4

One function of the Sierra sound system (Diesel) that you may want to consider also…

If you slowly increase the voltage, from an idle, you will hear the prime mover rev and transition for all 8 notches if you go slowly. How fast you get to notch 8 is definable; there are three different possible parameters you can program, centering around what voltage on the track is necessary to reach notch 8… you can pick a “high, medium, or low” option, so where the next part happens is not necessarily going to be as close to notch 8 on one locomotive as it is on another …

HOWEVER:

At some point in the “ramp up” when you reach about the maximum voltage that the Sierra can comfortably handle, you will notice that the prime mover continues to either run at full throttle or ramp rapidly up and down, and the horn begins to sound continually, usually a 14(l) over and over … This can be achieved with “straight” DC power, usually at the upper limits of how fast you’d want to ever think about going (well, unless you have one of those new P40’s) so most folks may not have seen this before… but it’s there.

In any case … when you hear this behavior, it’s time to back off on the power a bit!

Now you have to ask yourself … if it’s doing this with PWC (or filtered PWC for ersatz-analog) even at lower speeds, what voltage is the board really seeing, and where is that coming from?

There are physical limits of voltage beyond which a Sierra board will become a rocket ignitor, which are considerably lower than voltages (in spike, AND maintained form) that have been observed from selected popular model train power supplies by people with a whole lot more official recognition of their skills with electricity than my “Electrician’s Kid” certificate, and some pretty fancy test equpment too. The trouble is, an inadvertent combination of those two facts will yield a locomotive with smoke coming from places other than the stack.

That’s not a story I’m prepared to tell here, but I suspect you’ll hear the details someplace…

Matthew (OV)

#5

Curmudgeon to the rescue!

Rather like the “Geek Squad” in their little VWs.

#6

Many thanks Dave!

Matthew, your caution is there: Be aware of electrical spikes.

Here’s the how-to for adjusting your own Sierra sound for dismals:

1 - Set power on your test track to the loco with the loco with motors off;
(I choose the power setting at 15 volts as the most frequent setting when in a full-run position on the layout-- measured by at the test track)

2 - Turn the toggle sound switch to “on” starting the sound;

3 - Activate the toggle that determines sound loudness and listen for the horn;

4 - Hearing the horn sound (in my case repeatedly), hold the this same toggle switch in the opposite direction thus activating a series of horn “toots”

5 - Count seventeen toots – on the 17th one, push the same toggle switch the opposite direction three times…click, click, click.

6 - Immediately turn off the sound unit with the sound switch to “off”.

Check out the system by starting up the loco again with the sound switch on and the sound loudness toggle to a manageable level. Hopefully, as with my success, the loco will go through the sound sequence, including the horn sequence, and the level off at the 15 volt mark with just the running main-line engine sounds. When the power is reduced then the horn, etc. occurs.

NOTE: Dave advised there may be a need for an “18 toot” count instead of 17 counts
to achieve the result you want. Secondly, Dave further cautioned: “Be careful if neither remedy works, you may have an Aristo power supply that is spiking. Check it out with an oscilloscope (sp).”

Hope this is helpful.

Wendell

#7
Tom Ruby said:
Curmudgeon to the rescue!

Rather like the “Geek Squad” in their little VWs.


Or the old bearded guy in a Flathead with the pistola in his over-all pocket…