LION is told that a discharged capacitor looks like a short circuit.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Interesting explanation about short indications. I had mentioned in a previous response that I have been programming with the NCE system on a program track without getting any short indicators for locos with Keep Alives. However, in keeping with your explanation my methodology has been to place the loco on the program track and select it with the Power Cab and start the sound. Then I program using the JMRI. I do this not because I was aware of the need to charge the capacitor but I liked that when I set a CV the sound turned off as another indicator that the setting was being accepted along with the slight movement and the panel light flashing. Maybe that initial start up allows the current rush before programming and avoids the short indication. That seems to fold in well with what Digital is saying. Could it be true that even blind chipmonks sometimes do find acorns.
Marty C
Explination of how systems detect "shorts"
When there is a short, there's typically a near 0V difference between supply leg and the common leg.
So when you program on the program track, the voltage to the engine remains off TILL you try to program a value. So it powers up. This created a problem for older cabs as the capacitors on sound engines had to charge up before they could be programmed and respond. (That plus they couldn't supply the current) A cab would look at this like a short, or no response.
Having a low powered output was done intentionally as a means of testing a decoder hookup without blowing it out if there was a short. Worked great for standard decoders. Not so much for capacitor loaded ones. Capacitors are why high powered programmers were created.
High powered track programmers would would sometimes still have problems. Manufactures would increase the time a near 0 voltage differential (short condition) would be allowed before it threw an error. It's possible you have an older ROM in your power cab. (Older MRC sound decoders just loved to take forever to respond causing failures on even power boosted program tracks)
When you program on the main, the Keep Alive is already charged. So naturally it doesn't have a problem taking the command because the capacitors are full.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
Powercab uses broadcast programming at full power. Procab uses a current limited programming track. Powercab is more likely to program a capacitor equipped decoder then a Pro cab.
Same is true with Digitrax. Empire builder will program decoders that can't be touched with a Chief system.
Martin Myers
Mark R. I believe the problem lies in whether the capacitor is fully charged or not when placed on the programming track. If it is not fully charged when placed on the programming track, as soon as it sees voltage, it will begin to charge. The system sees this current draw to the capacitor as abnormal, so assumes it is a short. The trick may be to make certain the capacitor is fully charged when using the program track ? Now, that may cause yet another adverse effect. From Mark G's page .... The theory to READ CVs, is that the Command Station instructs the decoder to pulse the Motor according to the stored CV value. From these pulses of current from the C/S, the value is displayed. The only problem is a charged up KA2 or the Command Station may supply the pulses of current. If it is the KA2 supplying the power and not the Command Station, then there will be no pulses of current from the Command Station pulses to interpret to display the CV value, hence the 255 display. Out of all the keep alive modules I've installed, I've only had trouble programming two of them. For those, I installed a micro slide switch on the bottom of the engine to cut out the module for programming. Mark.
I believe the problem lies in whether the capacitor is fully charged or not when placed on the programming track.
If it is not fully charged when placed on the programming track, as soon as it sees voltage, it will begin to charge. The system sees this current draw to the capacitor as abnormal, so assumes it is a short.
The trick may be to make certain the capacitor is fully charged when using the program track ?
Now, that may cause yet another adverse effect. From Mark G's page ....
The theory to READ CVs, is that the Command Station instructs the decoder to pulse the Motor according to the stored CV value. From these pulses of current from the C/S, the value is displayed. The only problem is a charged up KA2 or the Command Station may supply the pulses of current. If it is the KA2 supplying the power and not the Command Station, then there will be no pulses of current from the Command Station pulses to interpret to display the CV value, hence the 255 display.
Out of all the keep alive modules I've installed, I've only had trouble programming two of them. For those, I installed a micro slide switch on the bottom of the engine to cut out the module for programming.
Mark.
Makes a lot of sense, thanks a lot for that
Modelling HO Scale with a focus on the West and Midwest USA
Mark,
Wow, you sure are up late, but thanks for that explanation.
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Alex,
I'm not sure it solves your issue. The more I think about Robert's response "that the in rush of current can cause a short indicator on some program tracks"I keep coming back to my experience. I am assuming and Robert can correct me if I am wrong but the operative word is "some" program tracks. I was running my layout with a Power Cab. When I added the SB5 I moved the Power Cab and panel to an off layout programming track. Now my question is why would an engine know the difference when first put on the track since it is not a program track until I press the button enough times to designate it. Again I will defer to Robert for the answer but I am thinking that program track set ups that might need a booster (and don't have it} could be susceptible. My NCE Power Cab on the program track does not need a booster and I have not had any problems. Which gets me back to the question of what are you using on your program track?
CSX Robert Marty C I am having difficulty understanding how the engine can run and program on the main but show a short when put on the program track... Because it takes less current draw to register as a short on the program track than it does when on the main. Some keep alive circuits will draw enough current charging the capacitors when first powered on that they can register as a short on some program tracks.
Marty C I am having difficulty understanding how the engine can run and program on the main but show a short when put on the program track...
Because it takes less current draw to register as a short on the program track than it does when on the main. Some keep alive circuits will draw enough current charging the capacitors when first powered on that they can register as a short on some program tracks.
Guess that solves my question, thanks a lot mate.
Robert,
Interesting. That is something I did not know or experience that type of short but I will put the info in my smallish knowledge bag. Thanks.
Marty CI am having difficulty understanding how the engine can run and program on the main but show a short when put on the program track...
I am having difficulty understanding how the engine can run and program on the main but show a short when put on the program track. You also said the engine runs and programs on the program track with another decoder in it. Can we look a little deeper? Are you using the same NCE system on both the layout and program track? A short indication on the NCE Power Cab would be for the system to shut down and try to restart then shut down again and cycle to restart until the short is removed. Is this what you see when you put the loco on the program track? Sorry to keep adding questions but the more detailed the info the better to assist from afar.
Marty C The problem could be unique to the Bachman with the KAT24 but I don't think it is a problem with the NCE system.
The problem could be unique to the Bachman with the KAT24 but I don't think it is a problem with the NCE system.
Perhaps an issue with the combination of a KAT24 and the noise suppression capacitor(s) on the Bachmann PC board?
-Fritz Milhaupt, Publications Editor, Pere Marquette Historical Society, Inc.http://www.pmhistsoc.org
With all due respect to Cacole, I have my Power Cab connected to my program track and have successfully read and set CV's for loco's with a KAT24 and other TCS non sound decoders with Keep Alive. I do not however, have any Bachman locos. The problem could be unique to the Bachman with the KAT24 but I don't think it is a problem with the NCE system.
More Amperage is applied to the decoder when Programming on the Main than with the Programming Track setting, so the keep alive is probably drawing too much power from the DCC system when you try to use the programming track and is reading it as a short.
Which NCE system do you have -- PowerCab or PowerHouse Pro. The PowerCab is limited to 2 Amps output when Programming on the Main and even less when you use the "Use Program Track" setting, so the inrush current of the Keep Alive module is overoading the system.
Okay clarifying
It's a Bachmann Spectrum J Class, TCS KAT24 decoder. Plugged into the 8pin plug. Just curious if anyone has had the issue, because it runs and programs fine(on the main) but each time I place it on the programming track, Short Detected, shows up.
Like Paul said I'm not sure we have enough information. I assume from what you said that you put another decoder in the engine and it worked fine, not that you have two decoders in the engine at the same time. I have an NCE system with the SB5. I use the Power Cab on a separate program track and have TCS Keep Alives (KA1 and 2) and Soudtraxx current keepers in all my sound equipped engines. I have not experienced any short indications on either the layout or the program track. If you recently installed the Keep Alive I would "guess" the problem is in the installation. You should check to make sure the connections are right and that you don't have a bare or crimped wire touching a component on the decoder. Also check that you didn't leak some solder from the connection on the decoder to another component. That is something that I have experienced and it smoked the decoder.
Please clarify...is this a TCS decoder with integral KeepAlive attached? Or did you add a Keep Alive to a decoder? What loco?
It could be an in-rush current issue but I don't know the details, sorry. I did add a LokSound Select to my Athearn GP9 and, since it before/after tended to hiccup at my 90 degree crossing trackage (more than any other loco) I added a capacitor and needed resistor, hooked to the decoder per the instruction manual. That setup (different than yours) works fine with my NCE 5A PowerPro, both program track and the mainline.
http://www.esu.eu/en/downloads/instruction-manuals/digital-decoders/
Paul
Modeling HO with a transition era UP bent
Has anyone run in the issue of a Keep Alive decoder throwing up "fake shorts"? Using the programming track with an NCE system, it keeps saying short detected. Although another decoder in the same locomotive works fine, so I am assuming current from the KeepAlive module is running to the motor even when it is on the programming track. Anyone had any similar experiences?