seems like you are separately measuring the voltage between the rails and possibly ground. don't understand why you said 13.1V - 12.9V. i'm expecting a very small voltage.
but i now realize, that that voltage is unlikely to be zero since the boosters are at slightly different voltages. i think the booster voltages would need to be adjusted to be as equal as possible at the gaps to make the measurement i've suggested.
considering this and the confusion about how to measure, i don't think there's any point in continuing.
greg - Philadelphia & Reading / Reading
Using a multimeter on the gap i measured:
stretch A - stretch B
13,1V - 12,9V
rail 1: 1,3V; rail 2: 1,8V
stretch B - stretch C
12,6V - 13,2V
rail 1: 1,0V; rail 2: 1,1V
betamaxPolarity is a term that belongs in the analog world and should stay there. In Digital Command Control there is no concept of polarity. DCC only has phase, meaning On or Off.
remember this is digital data modulating a voltage on the rails. the digital data may be 1s and 0s, but the modulation is voltage polarity (analog world)
the S-9.1 DCC standard says polarity
The NMRA baseline digital command control signal consists of a stream of transitions between two equal voltage levels that have opposite polarity
i interpret polarity as you've reversed the wires
i don't believe the polarity is wrong. i'm curious, repeat "curious", if there is a phase error which i believe is measurable as a small voltage difference.
if there is, repeat "if", i wonder if it could explain this problem.
FoscMy locomotives AC 6000 BLI and J1 BLI, for the first time on that specific tunnel, unexpectedly stop and reverse
it seems to me the only way for the loco to stop and reverse is if commanded via DCC packet unless there's something specific to the decoder
a momentary ( < ~10s usec) could corrupt a DCC packet. is it possible that it can repeatedly corrupt a packet such that it's interpreted as a reverse command? (seems unlikely)
This still does not jive witht he reported issue. Having the phase wrong across power disctircs would cause a short when a loco crossed the gaps, not cause them to change direction. The phase of the DCC signal does not determine direction of travel (if it did, autoreversers couldn't work).
Unknown if MRC calls for it, but most other systems call for a high capacity (same size as the main power bus) common wire between all boosters and the command station, because when there is a potential difference across gaps, this is where the current flows. Without a dedicated common, it tries to flow through the control bus cable, which is in almost all cases just thin telephone or network cable. If the booster has an optoisolated input, then this doesn't matter.
Also that mosnter MRC booster should not be connected directly to the rails in HO and smaller scales, 8 amps can melt a lot of plastic, and no HO train needs 8 amps. Splitting that up with circuit breakers makes better use of all that power, with less chance of a derailment melting you favorite loco. Of course, MRC doesn't sell circuit breakers, so they leave that out of their instructions.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
gregc Fosc i'm asking if their "phases is different" How can we know this for sure, except by simple visual observation? by measuring the voltage between the rails from different boosters across the gap dcc polarity changes every ~50-100 usec. a 1 usec phase difference is ~1-2%. 1% of 14V is ~0.14VAC while this results in a short, i doubt it is long enough to trip a breaker. however, i wonder if it is measureable and if it could cause the problems you describe. as i said, it should be 0VAC
Fosc i'm asking if their "phases is different" How can we know this for sure, except by simple visual observation?
by measuring the voltage between the rails from different boosters across the gap
dcc polarity changes every ~50-100 usec. a 1 usec phase difference is ~1-2%. 1% of 14V is ~0.14VAC
while this results in a short, i doubt it is long enough to trip a breaker. however, i wonder if it is measureable and if it could cause the problems you describe.
as i said, it should be 0VAC
Polarity is a term that belongs in the analog world and should stay there. In Digital Command Control there is no concept of polarity. DCC only has phase, meaning On or Off.
If you read a small voltage across a gap, that is a potential difference, not a phase difference, between the two districts. A large voltage means that one side of the gap is energized and other other is not, they are out of phase.
Fosci'm asking if their "phases is different" How can we know this for sure, except by simple visual observation?
betamax I think you are confusing the power supply with the track voltage. Don't worry about the phasing of the AC input to your power supplies, it is irrelevant. Phase in DCC refers to the state of the rails. If you measure across a gap in the rail, no voltage means things are in phase. If there is voltage, not just a few volts, one power/booster district is out of phase with the other. A couple of volts would indicate there is a slight difference in voltages between the two rails. Something like 12VAC indicates an out of phase condition.
I think you are confusing the power supply with the track voltage. Don't worry about the phasing of the AC input to your power supplies, it is irrelevant.
Rich
Alton Junction
Fosc richhotrain Fosc There is one thing I forgot to mention earlier, and it might be important: the problematic section is powered by an MRC booster (10A / 8A). This is isolated from the main control station, according to the manufacturer's instructions. Checking the connections of the two installed boosters, we found that they did not follow the trunk line layout. I refer to the data transmission line (Cable cat 6) between the control station and these two boosters [Note: the power supply itself of the line (bus) already followed the layout of the main line with the two interruptions due]. Well, by fixing the instruction links via the data cable mentioned earlier, I think the distressing problem has been solved Had the OP mentioned two boosters at the outset, this thread would have gone in an entirely different direction. Glad that he got his problem solved. Rich Yes, Rich, but I don't understand how not following the route with data cabling may have caused that disastrous problem.
richhotrain Fosc There is one thing I forgot to mention earlier, and it might be important: the problematic section is powered by an MRC booster (10A / 8A). This is isolated from the main control station, according to the manufacturer's instructions. Checking the connections of the two installed boosters, we found that they did not follow the trunk line layout. I refer to the data transmission line (Cable cat 6) between the control station and these two boosters [Note: the power supply itself of the line (bus) already followed the layout of the main line with the two interruptions due]. Well, by fixing the instruction links via the data cable mentioned earlier, I think the distressing problem has been solved Had the OP mentioned two boosters at the outset, this thread would have gone in an entirely different direction. Glad that he got his problem solved. Rich
Fosc There is one thing I forgot to mention earlier, and it might be important: the problematic section is powered by an MRC booster (10A / 8A). This is isolated from the main control station, according to the manufacturer's instructions. Checking the connections of the two installed boosters, we found that they did not follow the trunk line layout. I refer to the data transmission line (Cable cat 6) between the control station and these two boosters [Note: the power supply itself of the line (bus) already followed the layout of the main line with the two interruptions due]. Well, by fixing the instruction links via the data cable mentioned earlier, I think the distressing problem has been solved
There is one thing I forgot to mention earlier, and it might be important: the problematic section is powered by an MRC booster (10A / 8A). This is isolated from the main control station, according to the manufacturer's instructions. Checking the connections of the two installed boosters, we found that they did not follow the trunk line layout. I refer to the data transmission line (Cable cat 6) between the control station and these two boosters [Note: the power supply itself of the line (bus) already followed the layout of the main line with the two interruptions due]. Well, by fixing the instruction links via the data cable mentioned earlier, I think the distressing problem has been solved
Had the OP mentioned two boosters at the outset, this thread would have gone in an entirely different direction. Glad that he got his problem solved.
Yes, Rich, but I don't understand how not following the route with data cabling may have caused that disastrous problem.
Fosci'm asking if their "phases is different" How can we know this for sure, except by simple visual observation? Considering that my MRC system works with AC (rectified), using a multimeter is not enough to verify the phase. How to do this, please? I believe that both boosters are in phase with the base station.
FoscYes, Gregc, there are a small difference between voltages of the section controlled by the main (3.5A) and the booster (8A), but not between both bosters
i'm not asking if the booster voltages are different.
i'm asking if their "phases is different"
In the present case, the problematic ex-section of the layout is found in the section that is controlled by one of the two boosters. And there is only a gap before it that isolates the central branch (which I call branch "B") from a section of the external branch "C" of my layout.
Yes, Gregc, there are a small difference between voltages of the section controlled by the main (3.5A) and the booster (8A), but not between both bosters.
My layout has the shape of a capital letter E. The base station controls the central leg, while the boosters command the outer branches of the "E".
i'm not asking to verify continuity. with the layout powered, i'm asking if there is a measurable voltage across the gap (there should be 0.0 VAC).
FoscChecking the connections of the two installed boosters, we found that they did not follow the trunk line layout. I refer to the data transmission line (Cable cat 6) between the control station and these two boosters [
because you mentioned the data cable between the command station and bootsters, i'm wondering if there is a slight phase difference between the two boosters.
Greg, with the layout shut off, and I doing use one multimeter, it's there no are continuity in the track both parts seccioned by gap.
FoscWhen I did install the two boosters, I opened gaps main track, observing manufacturer's recommendations.
do you know how close in "phase" they are? can you measure any (AC) voltage between the rails separated by a gap? (not the rails on opposite sides of the same tie)
I have occasionally seen stalling at circuit breaker or autoreverser boundaries. These only happen once, the first time a loco crosses the boundary after powering up the layout. I figure I might need to play with the trip current for the breakers, as something is mismatched.
If the booster has an adjustable breaker, you might try lowering that. In fact, that's a big booster, so you might consider getting some fast PSX breakers to protect the trackage from the booster at a lower current level.
It takes an iron man to play with a toy iron horse.
Yes, Greg. When I did install the two boosters, I opened gaps main track, observing manufacturer's recommendations. Thanks.
are you saying there are gaps in both rails near the tunnel and separate boosters are powering the rails on either side of the gaps?
There is one thing I forgot to mention earlier, and it might be important: the problematic section is powered by an MRC booster (10A / 8A). This is isolated from the main control station, according to the manufacturer's instructions. Checking the connections of the two installed boosters, we found that they did not follow the trunk line layout. I refer to the data transmission line (Cable cat 6) between the control station and these two boosters [Note: the power supply itself of the line (bus) already followed the layout of the main line with the two interruptions due]. Well, by fixing the instruction links via the data cable mentioned earlier, I think the distressing problem has been solved: my loco Bachman 2-10-0 Decapod has traveled the “defective” section normally, either in forward or backward. I will continue testing with the other machines I have, in order to see if that problem, apparently solved, can return in any way. On the other hand, I do not want to believe that a cable connection for data transmission, if it does not follow the logical sequence of the layout, could have such a disastrous consequence. But anyway ... Thank you for the many responses and willingness to collaborate with a stranger in difficulty ... Thanks, again, to those who responded, and a happy New Year to all Forum participants!
Could be an inductance-related problem. I've read that different decoders have different sensitivities to corruption of the DCC signal: https://www.dccguy.com/?p=5762
The only time I've experienced "weird" operations with my MRC Prodigy (not squared) DCC system similar to those the OP has described was when I forgot to assign unique cab addresses to each of my throttles, both tethered and wireless. If you have the MRC WiFi module, that has to have a unique address, too. Otherwise, you'll see all kinds of weird stalling, reversing, speed changes, etc.
Hornblower
Hello All,
This has happened intermittently on my pike due to dirty track with a Bachmann GE 70-tonner with a factory-installed PCB type DCC decoder.
When this unit ran over dirty track it stalled, the lights reversed momentarily- -as if resetting- -then the lights returned to normal, and then the unit moved in the original direction of travel.
This happened over straight track and not the unpowered frogs of the turnouts.
It did not actually move in the opposite direction for any distance as you described.
After the track was cleaned the "problem" went away.
Hope this helps.
"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"
How many throttles do you have? Could multiple throttles be addressing the same engine? If so, is one throttle in reverse while another is in forward? Could these engines have been in consists that weren't properly cleared?
gregcthe wireless handset communicates with the command station, not the loco inside the tunnel. i assume the rf path is not changing, unless he happens to be moving just as the loco enters the tunnel
Could there be a multiple issue, for example the locomotive bridging the reverser gap while simultaneously experiencing a transient loss of power? That might lead some decoders to 'reboot' in the wrong mode relative to what a reverser is doing at that same time...
If I understand correctly, he has certain locomotives that repeatedly exhibit the problem behavior, but others that don't show it at all. The next question is: is there any commonalty in the decoder types, or installation, or programming, in the 'problem children' that isn't shared by the others?
OvermodDid he not say 'wireless'? That has me thinking 'multipath' as a first knee-jerk response.
the wireless handset communicates with the command station, not the loco inside the tunnel. i assume the rf path is not changing, unless he happens to be moving just as the loco enters the tunnel