BLI locos stalling with sound on

[kewatin]

hi davefox, kewatin here
 the rails are mated fine and no elevation- strait&level. to be honest i did remove the rear traction tires,thinking it could be a pickup problem.
it makes no difference loco still stutters&stops at the same 3 spots,only when i press f8 &silence the sound the loco runs perfect even pulling my 8 via passenger cars. there is another fellow on another forum having similar problems.my layout is rather new &less than 2 yrs old and never have i experienced an electrical problem with it other than installing my turntable ,which i solved by using a digitrax reverser. i am wondering if this is an isolated mfg problem or a mystery in the making.i am thinking of lashing some weight on top of loco to see if that makes any difference.i do appreciate all the help this post is generating to hopefully solve this problem so this loco doesn't become a roundhouse queen.
 regards&later kewatin

[peteski]

I looked over the thread and we still have some unknowns as far as the exact behavior.  We do  know that they are running on DCC and we also know that when sound is turned low or off, they run well.

When the problem occurs, do the locos just slow down (without stopping) and continue running, or do they stall completely and have to be slightly nudged by hand to restart?

Or do they have hiccups (they come to complete stop then start again all by themselves)?

Is the problem also occurring when the loco is running light (as a single unit, not pulling a train)?

[bobthebear]

Good questions Peteski.
It appear to "switch off" with a click, and need a nudge to get it started again.
Stops on it's own, and when consisted. Then the other unit drags it until it re-starts.
I took mine apart yesterday. I notice that the feed wires from the truck pickups separately go to the decoder through a plug. I added jumper wires between the trucks as it appeared to be an electrical continuity problem and suspected the plug. Didn't make the slightest difference! So, is it the decoder?

[superchief]

I too am having the same problem with both the first run E-8 and PA's, I run DCC on old code 80, I notice that it will not stall on plain straight track, but when I hit a turnout I get a stall, sound dies and then a restart and it takes off.......I also own a big boy/ challenger and FP45 and have no problems with these engines or the sound, in fact the steamers run so well I am surprised when I clean the wheels that they had not stalled. I think the BLI engines just do not have a large enough capacitor, but it is far enough down the TO DO list have not really looked at the solution. Gordon

[kewatin]

KEWATIN here  peteski ,in my case the loco just out right stops,even with a nudge it is hesitant to start.doesn't matter if it is pulling cars or not. i lashed a 3 ounce weight to top of loco and again no difference.i have begun playing with speed steps,at speed step 7 ,it will run with sound with only the occasional hicup,any thing lower it stalls at same 3 spots.anything above 7 its fine but who needs a race engine.again i am using a NCE power cab and no other loco's give me a problem.again i really appreciate all the help&possible solutions to trying to resolve this problem.still no reply from tech service at BLI in florida.
 regards&later KEWATIN

[mmagliaro]

Guys guys... from what I'm reading here, the engine comes to a complete stop and requires a nudge to get it going again.

The mystery of why this only happens with sound on is VERY weird.   We will worry about that later.

The big question is, is it doing this because it is losing contact at that spot or not?   
I think you need to know that absolutely positively before trying to diagnose anything else.

Since you are able to pull the shell and tinker with wires, I suggest this. 
Jumper a pair of nice flexible wires to the pickups inside the engine,  clip-lead the other ends to the rails and then run the engine through that trouble spot. 

If the problem goes away, you absolutely know one piece of the puzzle: it is losing contact there.  All the other weirdness
about it only doing it with sound on, we can think about later.  First, it is crucial to know if the engine is losing contact
there.

If the engine STILL does this with clip-leaded feeds going to it, this problem is going to get a lot harder to figure out.
So I really suggest finding out if that's the case.

[peteski]

Bob, you mentioned a click as it stops.  Could the loco be causing a short across the rails somewhere (frog maybe) as it is traveling across the turnout?  Or is there no indications of any shorts and the click is probably coming from the speaker?

If any of you with the problem  loco have other similar locos which do not have the problem (and you are enough electrically and mechanically inclined), swap the decoders between the units to see if that makes a difference.

The fact that you need to nudge the model to get it to run seems to point to an electric pickup problem, but it doesn't totally eliminate other possibilities.

What happens when you run that loco light (by itself) with the sound turned on at high speed through the trouble areas?  Does it make it through without stalling?  Does the sound cut out then continue?

[victor miranda]

ok I'll give this another whirl.

is said:
track ok.
locos seem ok
sound decoder resets.

while I an not sure that the track is ok and the pick-ups are ok

we kinda need to find a way to test the sound unit.

( I know pick-ups are the weakest link here and no one is willing to
look at it as the cause...)

peteski, the click could be from the decoder shut down.

victor

[Doug G.]

Ok, I don't do DCC so pardon me if this seems elemental (I do know computers and other electronical devices, however), but I assume the decoders retain their settings even if power is momentarily lost, without having to receive those setting again?

Doug

[victor miranda]

the decoder does most of the reset quickly.
it usually needs to re-recieve the command to do a speed.
as I understand it some commands are repeated at regular intervals.

... I wonder where I read that tid-bit...

I will have to test that.  I recall picking up a DCC loco and replacing it
and the loco didn't move. 
... My MRC command 2000 is not sophisiticated.


victor

[Doug G.]

That could be a clue.

Doug

[peteski]

Decoders retain their CV settings permanently, unless their "brain" is "blown" by some large voltage spike. But in that case the decoder would not be able to restart at all.  However as far as picking up after power loss, that might be dependent on the decoder manufacturer.  I think that most decoders come back from a reset (which in itself might take from a fraction of a second to more than a second) with the speed set to 0.  They at that point wait for DCC data packet which is addressed for them and which contains the speed step value.  The frequency of the packet being retransmitted also seems to vary between the manufacturers of the command stations.

The need to nudge the stalled loco  still seems like a power pickup issue.  Another good thing to observe would be to have the headlight on then check if the headlight stays on when the loco stalls, before it gets a manual nudge.

I'm still curious about how the loco behaves when running at high speed through the trouble spot with the sound turned on full blast.  Will is still stall or will it be able to run through? 

[mmagliaro]

...
...

( I know pick-ups are the weakest link here and no one is willing to
look at it as the cause...)

....
...
victor

Hey, wait a minute .... I AM!     

Seriously, Victor, I agree with you.  Everybody is too preoccupied with the weird decoder behavior.  I admit,
it does not make sense that having the sound on should affect the engine, nor make it come to a dead stop requiring a nudge, when it doesn't do that with the sound off.  But that may be a bizarre property of the
decoder that we never understand.  And before bothering with that, we should find out if the engine loses contact at that spot or not.  Hence... the jumper wires to remove all doubt.

[victor miranda]

Hey, wait a minute .... I AM!     

Seriously, Victor, I agree with you.  Everybody is too preoccupied with the weird decoder behavior.  I admit,
it does not make sense that having the sound on should affect the engine, nor make it come to a dead stop requiring a nudge, when it doesn't do that with the sound off.  But that may be a bizarre property of the
decoder that we never understand.  And before bothering with that, we should find out if the engine loses contact at that spot or not.  Hence... the jumper wires to remove all doubt.

Hi Max,

I almost had peteski here, too.

the problem is that the pickups are very likely involved.
there are darned few ways to test the entire system.

the power supply to the tracks
the tracks to the loco
the loco to the decoder
the decoder interactions with the motor and sound unit.

we can test the track somewhat.
we may be able to get confidence in the loco

what we cann't do is measure the set of circumstances that
CAUSE the decoder to 'reset'

one decided possibility
is that one decoder shuts down and the other two are suddenly loaded
and they bring the track voltage down enough to reset the first one again...

there are a lot of possibilities.
what I have not seen in sound decoders is a set of brown-out specs.
( I have not gone looking to be honest...  I know they exist for the
PIC processors often used for decoders)

last and not least.
I have been trying hard to find a reliable pick-up system.
so far I will state if a wheel dropping into a frog is the problem
the entire pick-up system is close to failure.

the other thing I can state is that one wheel dropping into a frog
will change the resistance of the pick-up system.

so sound decoders, because they use more power,
will react more to adverse pick-up conditions.

what I can't do is state I know the cause.
once we eliminate causes... what ever is left....
is the cause. and it may well be in the design of the decoder.
....
I guess I finish this.
the pick-up problem is ordinary for n-scale.
I can eliminate it in o-scale (I think I did many years ago)
it exists in n-scale and every time I think I have a solution it comes back.

the decoders for n-scale have to'understand' this reality
and function with brown-outs.

so while fixing the pickups will 'solve' the problem...
you will be in there cleaning the solution a lot.

victor

[peteski]

I don't know Victor, if you read my earlier posts I seem to mention power pickup problems few times too. 

The detailed questions I have been asking were phrased in a way which should let us know whether it was a pickup problem. The last set of (unanswered yet) questions I posed might shed some more light on this problem.