BLI F3 and F7

[peteski]

hi maletrain  that is exactly what I did.   new loop of kato unitrack  ran the engines roundy roundy in one direction did same number of revolutions in the opposite direction and then repeat  several  times  swap out the command station and power supplies repeat till I ran through the list. Then repeated the same test in a different order.  and got the same results.. The wave form on the scope was similar for the higher end command stations,  digitrax bd100 dcs150 and dcs240   were close enough  the dcs51  (zephyr output was not as clean with some spikes)   decided to send that unit back to digitrax to look at it,  The NCE powerhouse pro was similar to the digitrax output and clean.  behaved well.    NCE power cab was a different story  better signal than the DCS51 but worse than the NCE powerhouse pro.   The speedups and slow downs appeared like capacitors charging and discharging in the motor circuit.   this start run stop behavior was very predictable,  like a time constant.      I will be waiting for digitrax repair folks feed back on the zepyhr.    My power cab will be most likely be sent back to NCE for examination.         I do like the engines with their cosmetic flaws and all.    on the higher end command stations they were running like swiss watches.     Took the locos down to the club which tend to have dirty track and it still ran smooth as silk,  im impressed  Club layout  has one dcs240 along with 6 db220 dual boosters.       The bottom line is the paragon 3 appears to be  working as advertised for my systems that I use.  The entry level systems I typically run only z scale with standard small decoders from ct, digitrax, esu, zimo and tcs.  I am not worried about those units.

I'm not sure I understand this.  How can the cyclical slow-down/speed-up of your model loco be caused by the command station/booster?  Especially if you were monitoring the signal waveform on your oscilloscope and it remained constant?

Unless the DCC signal's amplitude gradually got (drastically) lower then higher again, in order for the loco to behave like it does the command station would have to send gradually lower speed step packets, then gradually increasing speed step packets to the loco's address. Without the operator turning the speed control knob on the throttle.

[cgw]

I think the packets are not clean that the decoder receives  as a result the decoder misinterprets the bitstream that it receives

[peteski]

I think the packets are not clean that the decoder receives  as a result the decoder misinterprets the bitstream that it receives

But in order to gradually slow down, the unclean packets would be interpreted byt hte decoder as gradually decreasing speed steps like 30, 29, 28, 27 . . . 3, 2, 1, 0. Then the same thing in reverse to get it up to speed.  I just don't see that as being realistically possible.  If you understand how the data is encoded in DCC packets, you will understand what I am saying.  If the problem was random jumps in speed (faster and slower) then I coudl see a "dirty" DCC signal causing it, but a repeating cyclic slowdown and speedups just are not something I think would be caused by "dirty" DCC packets.  Too bad that you don't have one of the Pricom Design DCC Pocket Tester.   Using that tool you could verify the timing and quality of the DCC packets and also snoop on the packets sent to that model. I find that tool very useful for DCC troubleshooting.

[cgw]

I have sent the digitrax dcs51 unit off for repair that was the worst offender .   I will know in about three weeks what they find out.      I am begging to wonder if the unit could not keep up with the current load of the sound decoder.?   When you watched the loco go roundy it would come up to speed slow down stop. then the engine would come back up to speed and then repeat. This would go on and on till I shut I down.  Very odd behavior.    could not duplicate it with the other digitrax units.

I always wanted to get one of the pricom packet testers but I promised the significant other that I would cut back on the hobby purchases. (after I get ;my bli t1's)

[peteski]

I have sent the digitrax dcs51 unit off for repair that was the worst offender .   I will know in about three weeks what they find out.      I am begging to wonder if the unit could not keep up with the current load of the sound decoder.?   When you watched the loco go roundy it would come up to speed slow down stop. then the engine would come back up to speed and then repeat. This would go on and on till I shut I down.  Very odd behavior.    could not duplicate it with the other digitrax units.

I always wanted to get one of the pricom packet testers but I promised the significant other that I would cut back on the hobby purchases. (after I get ;my bli t1's)

I agree that the behavior is very odd, and I'm not trying to argue here, but  if you were observing the DCC signal on your oscilloscope, you would see the gradual reduction on voltage in the signal until it was low enough for the model to stop, then gradually raise again.

Also, all the DCC boosters (or command stations with built-in booster) I have ever worked with would totally shut down if excessive current was being drawn (the electronic circuit breaker would trip).  No gradual fade out.   Also, how much current can the suspect DCC booster supply to the track, and how much can a single N scale sound-decoder-equipped model consume?

You mentioned that the model worked fine on NCE Power Cab. I own that system and it's wall-wart is only rated for 1.35A.  Probably one of the lowest amperage DCC systems you tested, and it worked well.  Actually, you could enable the Power Cab's built in digital ammeter (shows the track current on the throttle's display), so you'll see exactly how much current that loco consumes.

But I just thought of another possibility (more in line with your suspicions):  Do we know how that decoder behaves when it no longer recognizes DCC packets on a DCC-powered track?  Would it simply continue at the speed from the last speed command it received, or would it come to a stop (either gradually or abruptly)?  Maybe you are onto something.  That DCC Pocket Tester would tell you whether the DCC signal is compliant with the defined standard, and if not, what is out of spec.  Unfortunately Pricom discontinued that tool, so the only way to get one now is 2nd hand.

[daniel_leavitt2000]

Has anyone run these engines without the bubble-wrap? Or tried adjusting that blue wire? My gut tells me this is an overheat or RF issue.

[Point353]

... new loop of kato unitrack ...

What is the length of that test loop and how many feeders do you have connected to it?

[cgw]

the test loop was the 13 3/4 radius 45degree track sections with a 9" inch straight sections to make it easier to put the locos on and off.   Single feeder.      Feeder to command station was less than 2 feet.      I did check to see if there was a voltage drop and there was none on the track .  So I know it was not an result of a voltage drop due to run length.

As far as a thermal issue with bubble wrap or the antenna the answer is: no it does not influence the results.   I say this since I can change the command station out and then run the loco for hours without a hiccup.    put the offending units in place and the bad behavior comes back in.      I measured the temperatures with a FLIR infrared camera with a calibration dot and the temperature rise was minimal.  So it could not be a thermal heat issues.      Marks engines ran hot I understand, the probable cause is he was running his engines near the upper end of the allowable voltage range 16V.    The majority of N scale motors are best run at 12 volts and they are the happiest at that voltage level.    The only real way to measure the voltage level of a DCC signal accurately is with a scope.    NCE some where on the web published a simple circuit of a few passive components that would allow a std voltmeter to be used.    Better but a scope still is the best.   Ramp meters are ok but they cannot capture the voltage spikes and odd waveforms since they are averaging devices.     I installed ramp meters on every booster and command station outputs at the club and are all set at 12 volts. (  Digitrax DCS240 and DCS220 boosters powered by a regulated 15 volt 30 amp switching supply).     So far knock on wood  we have not had any issues with any members equipment on that layout.      The paragon 3 equipped locos run with no observable issues.       

[Maletrain]

Cgw, how are you measuring the temperatures with your set-up?  If you are looking for an infared image of hot components through the loco shell and bubble wrap, how confident are you that you can detect a single SMD on the decoder board that is overheating?

One of the other things that I note in your experiments is that you seem to be having the wonky behavior right away when on the systems that you think cause it.  But, Spookshow's experiences seem to indicate that it takes a while for this behavior to develop, at least in a new locomotive.  His review says they worked great right out of the box when not pulling anything, then talks about how bad it gets after 15 hours of running.  It sounds like at least he thinks it has something to do with the gear mesh getting out-of-wack and the decoder's response to that.

So far, my own minor testing has been with a Power Cab feeding 2 places on a Kato Unitrak loop with 142.5" of track. Track is 15" radius with 15° 19" radius "easements" and straight sections 22" long. Feeds are on the opposite ends of the straight sections.  There are no isolation joiners in the track, so it is electrically a single loop, not one or two straight sections.  That has never caused a noticeable problem, so far.

All of my new BLI F-7 units have run very smoothly right out of the box, but under no load, so far.  All have exhibited sounds that seem to indicate throttle-up and throttle-down actions with no actual throttle inputs.  However, when I turn off the sound and watch the locos carefully, there is no apparent actual changes in speed.  The throttle-up and down sound effects tend to occur at about the same places in the loop, but not every time the locomotives pass those places.  Current draw as indicated on the Power Cab seems to be fluctuating between about 0.08 and 0.12 amp in a manner that does not appear to correlate with the sound effect changes.

[Point353]

the test loop was the 13 3/4 radius 45degree track sections with a 9" inch straight sections to make it easier to put the locos on and off.   Single feeder.      Feeder to command station was less than 2 feet.      I did check to see if there was a voltage drop and there was none on the track .  So I know it was not an result of a voltage drop due to run length.

My concern was more about maintaining the integrity of the DCC control signals as they passed through multiple rail joiners, rather than any voltage drop.
There used to be posts from a fellow called "powersteamguy", with a sizable layout using Kato track and DCC control, who advocated soldering feeders to every single piece of track.

[Carolina Northern]

Bob passed away last year, but his advice is still good. There should be a jumper on each piece of track - Unitrack or flex. Never rely on a track joiner for electrical continuity.

Don

[RBrodzinsky]

Wow, yeah. Over a year since we lost Bob. But, yep, the feeders on every piece are to avoid relying on joiners for conductivity, not specifically signal integrity. I don’t see a reason why some command stations would work better than others in this situation, though. Just because they are lower amperage wouldn’t affect operations unless something is drawing their current limits. A single loco won’t come near it. And the higher rated units won’t be putting out higher currents, only what the loco and track are drawing.

[atsf3751]

I don't have a feeder to every rail, all my track joiners are soldered. This does not cause any expansion issues on a layout in my house in Southern California.

[NorsemanJack]

The majority of N scale motors are best run at 12 volts and they are the happiest at that voltage level.    The only real way to measure the voltage level of a DCC signal accurately is with a scope.   

With DCC, isn't the decoder the only electrical component that would "see" the higher voltage.  I thought the DC motor still just received a straight DC feed at whatever voltage correpsonded with the track speed (typically far below 12V).  That said, I do understand that a higher DCC voltage might make the decoder "run hot."

[NorsemanJack]

Bob passed away last year, but his advice is still good. There should be a jumper on each piece of track - Unitrack or flex. Never rely on a track joiner for electrical continuity.

Don

This assumes that with electrical connections, a soldered joint is always superior to a mechanical joint.  This is simply not true (I'm including all applications, not just model railroading).  Kato's Unitrack rails and (current design) Unitrack joiners form an excellent mechanical connection and there is no need to solder a wire to every rail.