Strange Problem when I power up my NCE SB3a

[sysout10]

I have had my NCE SB3a for several months using my Power Cab now as a throttle, love it worked great for months. Recently when I power up the system, the locos try to start, my lighted cars flicker, the loco headlights blink, for several minutes, then suddenly all is normal, all locos run fine. While this blinking is going on, I cannot communicate to any loco. It is like the system is trying to boot up, but gets stuck and recycles several times. It is a bit scarry, because the locos are making erratic sounds while this is going on, it takes 3-5 minutes to get through this bizarre state, and concerned one of these power ups will wind up not coming out of this "funk". Anyone run into this with an NCE SB3a or other system? Any ideas on how to resolve? Thanks,

[cacole]

It sounds like you may have overloaded the SB3a with too much current draw from the lighted passenger cars.  Try removing them from a powered track when you shut down, and see if the locomotive headlights still flash when you turn the system back on.

If you still have the problem, I'd suggest you contact NCE and describe the problem to them.  They have been very good at answering email.

[aj1s]

As with many of these kinds of problems, it helps if you can identify what changed between when the system worked normally, and when it quit working normally. 

Is it possible that trains were stopped/placed at entrance AND exit of an automatically controlled reverse loop? Is it possible the loco is on the entrance/exit, and a lighted passenger car is on the exit/entrance?

What kind of short circuit protection do you have for the layout? None, light bulbs or circuit breakers?

Have you added any sound decoders since it was last working normally? They can draw a lot of current at start-up, which, depending on your short circuit protection scheme could do strange things.

Has any track wiring changed?

Andy

[sysout10]

Thanks, think this may be due to an overload at startup, I removed 2 locos from the layout, these startup at every power up and removed several lighted passenger cars and resolved the problem. When I upgraded to the 5 amp SB3a from 2 amps Power Cab, figured this was more than enough power. Any idea what a Soundtraxx Tsunami Decoder draws at startup? I think there is a CV setting to have the loco NOT power up at startup, will need to find that, I have several locos with Soundtraxx Tsunami Deocders on the layout and all power up at startup, thinking if I can have these NOT power up, and only power up when I run one, this may allow me to have more locos on the layout, but not active until I call them up. Any idea on the CV number, setting to have the loco NOT power up at startup? .

[BNSFRailWay Modeler]

I'm very good with soundtraxx tsunami and they will draw about .6 amps at idle then when throttling up is about .8-1 amp now that current will level off one the speed is reached.

[tstage]

sysout,

I found this on one of the Yahoo! sites:

http://groups.yahoo.com/group/soundtraxx/message/21227

Read the response left by Gary near the bottom.

I also found the Tsunami manual online.  On pg. 46 of the manual there is a mention of "Quiet Mode", which sounds exactly like what you want to do.  You access Quiet Mode it via CV113.  The default is [0] so that the decoder sound powers up at start up.  Any non-zero value between 1 and 255 tells the decoder how long (in 1/10th second increments) to delay before turning the sound off at start up.  So, setting CV113=1 (1/10 seconds) should be quick enough to not overload your SB3a at start up.

Just a suggestion.  Since you have so many Tsunamis, it might be a good thing to download a copy of the Tsunami manual to your computer for reference.  I like to print them out and stick them in a binder.  That way I can write notes in the margin.

Hope that helps...

Tom

[locoi1sa]

  I am not absolutely sure but I think that the SB3a can be configured to trip slower so it has a chance to charge the capacitors before shutting down. Look in the manual under command station configuration.

  Another idea is to park the unused locos on tracks that have one rail to a toggle switch. This way the inrush current will not hit the SB3 at once. Separate power districts powered through either a PSX or on-guard breaker is another. Charging all those capacitors at once is what is tricking the booster to trip.

        Pete

[CSX Robert]

sysout10

...When I upgraded to the 5 amp SB3a from 2 amps Power Cab, figured this was more than enough power...

You probably have enough for running the layout, just not enough for the initial power on current surge(more on that in a minute).

sysout10

...I think there is a CV setting to have the loco NOT power up at startup...

This probably won't help. Even if you have the sound initially off, the decoder itself still "powers up." The problem is not the current draw of the decoder's sound, but the current draw of the "keep-alive" capacitors as they charge up. You will have this current surge whether the sound is on or off.

Probably the easiest solution is to have isolated sidings or sections of the layout with on/off switches so that you are not trying to power up all of the locos at once. CVPUSA makes a booster that can supposedly tell the difference between sound decoder surge current and a true short. I also remember seeing some circuits that would briefly limit current at power on to prevent the booster from tripping and then apply full power after giving the decoders enough time to power up(I don't remember where I have seen these right off hand).

[sysout10]

Thanks for all your replies, all have been really helpful. I think CSX Robert has nailed the cause, that the surge at power up to load several of the decoder capacitors is overloading the SB3a. Just wish those capacitors would bridge a few touchy unpowered turnout frogs :-) Reason I say this is that when I power on the system, the several locos do initially go into startup sequence, then start flikering, then go back into startup sequence, then start flikering, this repeats several times, then eventually all locos complete startup sequence successfully and then run normally. I am thinking that in each cycle of these short startup sequences, some current is getting to the decoder capacitors, and this builds up through 3-4 cycles, then eventually reaches full charge and does not draw as much current, which then does not overload the SB3a. Since I have removed some of the lighted passenger cars and a few locos, have not had any issues at power up. Did not realize that the decoders would draw 0.6 amps at rest, and 0.8 to 1.0 running. I have a Proto 2K F7 ABBA lash up (all powered with Soundtrax Tsunamis) and 5 other locos on the layout. The F7 ABBA will draw 3.2 amps when running, and the other locos could draw up to 3 Amps at rest, and the lighted cars will draw which would put the total over 5 Amps. This flaky issue started when I put 2 of my locos I had off-line back on the layout. This is the extra load at startup that must have put the load over max. Surprised there are not more frequent overloads. Looks like I need to buy an amp meter to read what is being drawn. Thought the 5 Amp system would be plenty - and thanks for all the other suggestions, will use the CV settings to have no sound for the locos at power up, and will add SPDT switches to a few sidings to keep some locos and lighted cars "off-line" - really appreciate helping me see the cause and solutions on this one, like many "mysteries" once you get some data and facts, the obvious that was hidden, becomes even more obvious, but not always for the poor fool like me trying to figure it out without some help thanks alot

[rrinker]

 It's not just the sound decoders and their capacitors, those lighted cars also cause an inrush issue, incandescent bulbs do the same thing, there is an initial high current inrush whent he bulbs are cold and then it drops when the light

 It's common to see a recommendation for using a low value resistor even on 12-14V bulbs when using them for DCC functions, for this very reason. The bulb may be rated to handle the full voltage without a problem, but the initial inrush can exceed the capacity of the decoder's function output with respect to current., leading to a blown function.

          --Randy

 

[CSX Robert]

In my previous post I mentioned circuits that would limit the current at power on to help with this issue. Check out the "TurnOn Module" on this page: http://www.tamvalleydepot.com/products/dccpowerfrogjuicers.html, a ready made circuit to do just that.