Need help - DCC Engine Not Running Smoothly

[bklynman01]

I laid some brand new track this weekend, and tested it using a little 0-6-0 Tank Forward switcher. This little engine that could... just couldn't.

It looks as though the engine is losing electrical connection to the rails. I cleaned the rails off, but they seemed to be pretty clean already. I used a Q-Tip with alcohol to clean the wheels, but not much grime came off. I even tried to over-clean the rails and let the wheels turn on the alcohol residue to hopefully get the wheels a little better. But, the engine still runs like this...

This is all the dirt that came off the rails:

And finally, I think this might be a cause of some problems, but I'm not completely sure. The wheels look like they've run over gravel under full load...

Could all those little divots be causing my troubles? If yes, can they be buffed out or is it better to just buy new wheels?

Any advice is welcomed. I'd really like to get this engine running smoothly as most of it's running distance up the hill will be hidden and I don't want to reach into a tunnel to poke it forward every time.

Thanks in advance!

 

[Selector]

Unfortunately, those little blemishes are the result of possible impurities, less-than-excellent sintering or chroming, and micro-arcing during the application of voltage as the tires pass over uneven railhead. Even some slight rocking of the frame as the locomotive moves can cause wheel lift and some slight micro-arcing. With sufficient time, and temperature in the arcing, you'll get this pitting.

Even when tires look quite clean, they can still be dirty. Same for the metal wipers behind the wheel rims, or running over the metal axles if it has them. Some place a soaked rag over the rails and run the wheels over the rag to clean the tire treads. Or, use wires and metal clips to power the locomotive while it is cradled inverted. Use a Q-Tip with kerosene or lacquer thinner to wipe the tire treads.

The image shows that the locomotive is not run in a clean environment. All them fibers...tells me your works might be gummed up some.

If the rails are new, and you've scrubbed them, they're clean. Look to the locomotive. A broken wire, broken wiper, dirty wherever and whatever that results in poor conductivity, a tired or dirty motor, hard lubes in the gear tower, drivers slightly out of quarter that causes momentary binding in the rods....all these things could cause a steam locomotive to work poorly, if at all.

 

[bklynman01]

Thanks for the words Crandell!

Use a Q-Tip with kerosene or lacquer thinner to wipe the tire treads.

Well, there's no kerosene around, but I think there's some lacquer left in the garage, will have to look tonight. If the pitting is the real issue, how long would this be effective? Cleaning will happen anyway, but I'm just curious if replacing the wheels is the real long term solution. But if simply cleaning is going to do the trick, I'd much rather just do that.

A broken wire, broken wiper, dirty wherever and whatever that results in poor conductivity, a tired or dirty motor, hard lubes in the gear tower, drivers slightly out of quarter that causes momentary binding in the rods....all these things could cause a steam locomotive to work poorly, if at all.

All the electrical was my next step, didn't have time last night to tear it down and look at everything. Will disassemble tonight and check all contact points.

All them fibers...tells me your works might be gummed up some.

I took the picture right after using the Q-tip and before pulling those off. It's when I noticed that pitting that I took out my phone to get the picture. They were removed right after.

 

[PowrCab]

There is nothing that wrong with the wheel treads that it wouldn't run... Near all loco pickup wheels look like that, that close up...
In lowest pic, what is that wiry looking thing between the middle and front lower wheels ? Is that hair caught up in the rods/axles ?

 

[bklynman01]

There is nothing that wrong with the wheel treads that it wouldn't run... Near all loco pickup wheels look like that, that close up...
In lowest pic, what is that wiry looking thing between the middle and front lower wheels ? Is that hair caught up in the rods/axles ?

Not a hair, but a fiber from a Q-tip. I was wiping the wheels down when I noticed all the pitting, so I took the picture. Didn't think to finish cleaning the area before taking the picture.

 

[bklynman01]

Cleaning the wheels and contacts did not work. I took a series of short videos to show the steps, but they're not uploading for some reason.

By connecting some alligator clips between tracks and the contacts, everything runs fine. However, when all assembled, it's still real jumpy.

I took the shell off and found this broken blue wire. "THERE IT IS!" ...right? nope. I didn't even take a moment to look at what it was. It needs fixed, right, so do it anyway and don't look around. Well, it was the LED wire. So, now I can see the headlight blinking every time the engine jumps.

Still has trouble. I got tired of taking it apart and re-assembling (had to have done it 6 or 7 times), so all done for tonight. I'm convinced the issue is one of the connections either from the wheel to the contacts [wheel <--> copper] or where the wheel contacts connect with the chassis wiring [copper <--> copper]. Although, I guess the problem could still be the wheels but the only way to test that is to swap out wheel sets and see what happens.

Very frustrated...

 

[PowrCab]

I just don't think the Bmann wheel treads are the problem/swapping them out...Have you removed the bottom plate / look in there ? Could one of the drivers be out of quarter just enough to cause binding on side rod ? From the video it sure looks mechanical, not electrical...
And, yes, don't put the shell back on til you fix it...Is it still under warranty ?

 

[bklynman01]

I just don't think the Bmann wheel treads are the problem/swapping them out...Have you removed the bottom plate / look in there ? Could one of the drivers be out of quarter just enough to cause binding on side rod ? From the video it sure looks mechanical, not electrical...
And, yes, don't put the shell back on til you fix it...Is it still under warranty ?

When I talk about the contacts to the wheels and the chassis, I mean the contacts that are buried in that bottom plate. That's where a lot of my cleaning was going on - had initially thought that maybe some grease got on the contacts and the conductivity wasn't so good.

The tie rods look to be right at 90 degrees offset - I believe that's correct?

I'm leaning on electrical because the headlight turns off when the loco stops and motor stops buzzing. When it starts back up, the motor buzz comes back and the light comes back on. This all happens in under a second.

Could there be a CV that would help with this? It is a DCC engine, so perhaps a software setting could resolve the issue?

 

[Smudge617]

I don't think any CV will help, it's a mechanical or electrical issue, try inverting the loco and remove the drive wheels, then using some fly wires carefully touch the inside pick ups if it still stops and starts it's electrical, (if runs fine at least you know it's mechanical) If electrical try using a multimeter, could well be a wire that looks OK, but barely hanging on, literally by a wire.

 

[bklynman01]

Finally got the video to upload this morning...

When connecting the track signal directly to the board, it runs great, nice and smooth. The only thing missing during that test is full load on the motor (running freely). Also, the connections from wheel cover to the contacts that run to the board are not tested.

Smudge, I think I know what you're saying. That would be the next step in the troubleshooting progression, but didn't think to just leave the wheels off. Will have to try that when I get home from work tonight.

 

[Selector]

Such a lovely little engine. Very nice...and very smooth once underway. And apparently quiet. So I'm guessing it's not a cracked gear because that problem doesn't go away when it is in motion. Jerky. And often clicky. I don't see the rods being out of quarter because that also makes for periodic (in the true sense of that word) binding as the drivers' come back to the same position on the clock-face.

I'm almost suspecting brushes or magnets. Here, though, I have to defer to others because I have never taken a motor apart and repaired one.

 

[Smudge617]

Finally got the video to upload this morning...

When connecting the track signal directly to the board, it runs great, nice and smooth. The only thing missing during that test is full load on the motor (running freely). Also, the connections from wheel cover to the contacts that run to the board are not tested.

Smudge, I think I know what you're saying. That would be the next step in the troubleshooting progression, but didn't think to just leave the wheels off. Will have to try that when I get home from work tonight.

It seems to run ok when not on the track, and no weight on the drive wheels, plus direct power to the board, so I would check the pickups and wires, and also check the drive gears, you might have a mis aligned axle gear, or something along that nature, which is causing it to stick or catch as it rotates.

 

[PowrCab]

In the bottom photo in post #1 the simulated brake shoe of the upper front wheel looks like it's sticking out too far where perhaps the side rod rubs on it.
Yet how could that be if it's part of the bottom plate mold...Thus I know it's far fetched and likely just an optical. But just to be sure....

 

[D&J RailRoad]

The electrical path is from the track to the wheel to the wipers on the backside of the wheel to the decoder.
The wipers are the culprit. clean the backside of each wheel as well as the contact point of the wipers.
Don't use abrasives on the track or the wheels. The scratches will trap dirt and grease faster than a slick surface.

 

[bklynman01]

the simulated brake shoe of the upper front wheel looks like it's sticking out too far where perhaps the side rod rubs on it.

The picture does make it look this way so I checked and there isn't actually any contact. Good eye though!

also check the drive gears, you might have a mis aligned axle gear, or something along that nature, which is causing it to stick or catch as it rotates.

I've taken this engine apart so many times in the last few days that if there were a mechanical variable in flux, it would've shown itself by now. I do continue to check alignments and push rods every time though.

The electrical path is from the track to the wheel to the wipers on the backside of the wheel to the decoder.
The wipers are the culprit. clean the backside of each wheel as well as the contact point of the wipers.

Oddly enough, this was my plan for tonight. I took everything off so that I can see the wipers, backside of wheels, and everything in between. After a good cleaning, there was no movement when I put it back on the track! So, back to step one troubleshooting - where does the electrical connection seem to fail?

Check this out...

Sorry about the bad camera angle, I don't have a nice setup like some others do, so I just leaned my phone against a hopper and hoped to get the important content.

Any ideas? Looks like the resistance between the wheels and board is so much that the voltage needed to turn the wheels under load isn't getting there.
EDIT: Using a meter, measuring resistance from wheel surface to where the wire is soldered to the PCB, one side is measuring 320K Ohm, and the other is 200K Ohm. I don't have another loco readily available to check it's resistance values - anyone know what this value should be?

Frustrating... This little engine is taking much more time and effort than I wished it would. All other activity has basically stopped...

 

[D&J RailRoad]

That is odd. At this point, I would set the loco on the track then with one lead at a time I would probe for electrical path, one point at a time all the way from the rail to the solder point going into the decoder.

 

[bklynman01]

I did probe at each junction, but couldn't figure out how to do it on the track. What I found was that the highest resistance was between the wipers and the board. And the only junction in there is the connection between the wipers and the contacts that are soldered to the wires. There was a small heat shrink cover to protect that solder joint, so I cut it off and inspected. The wiring looked okay, but solder did not look good. I decided to resolder both wires, and of course one of the terminals falls off.

After resoldering I tried a piece of heat shrink I have here but it's much thicker and caused the plastic piece to not sit flat. So, I coated the whole piece and Soler joints with clear nail polish as an insulation. I figure if this doesn't work, it'll need replaced anyway.

Didn't get a picture of it, but while putting everything back together, the red wore broke off from the pcb. So, a little more soldering and it looked better than before.

After reinstalling everything, I check resistance again. From the wheel surface to PCB solder points, was reading under 20 Ohms - quite a difference from before!

So, back to the tracks...

Looked good at first, then the same issue started up again!! The LEDs are much brighter now though, so there's certainly an improvement in conductivity. I put the meter back on the wheels, and while holding the probe on the PCB, moved the other probe around on the wheels. While moving, the resistance is all over the place, ranging from a few ohms to hundreds of Kilo Ohms. That's when I decided I was done for the night.

 

[Smudge617]

I did probe at each junction, but couldn't figure out how to do it on the track. What I found was that the highest resistance was between the wipers and the board. And the only junction in there is the connection between the wipers and the contacts that are soldered to the wires. There was a small heat shrink cover to protect that solder joint, so I cut it off and inspected. The wiring looked okay, but solder did not look good. I decided to resolder both wires, and of course one of the terminals falls off. View attachment 142898
View attachment 142899
After resoldering I tried a piece of heat shrink I have here but it's much thicker and caused the plastic piece to not sit flat. So, I coated the whole piece and Soler joints with clear nail polish as an insulation. I figure if this doesn't work, it'll need replaced anyway.
View attachment 142900

Didn't get a picture of it, but while putting everything back together, the red wore broke off from the pcb. So, a little more soldering and it looked better than before.

After reinstalling everything, I check resistance again. From the wheel surface to PCB solder points, was reading under 20 Ohms - quite a difference from before!

So, back to the tracks...

Looked good at first, then the same issue started up again!! The LEDs are much brighter now though, so there's certainly an improvement in conductivity. I put the meter back on the wheels, and while holding the probe on the PCB, moved the other probe around on the wheels. While moving, the resistance is all over the place, ranging from a few ohms to hundreds of Kilo Ohms. That's when I decided I was done for the night.

Interesting phenomenon your having, might be an idea to remove the PCB altogether and just join the wires up, see if that improves anything.

 

[bklynman01]

might be an idea to remove the PCB altogether and just join the wires up, see if that improves anything.

I had thought of this, but decided the PCB was not the issue. Reason being that when using alligator clips to connect the track signal direct to where the wires are soldered to the PCB, everything works fine. This means that the PCB and decoder are receiving and processing the signals without an issue. Therefore, the issue must lie between the wheel surface and the PCB. Hence all the work on the tiny terminals inside the wheel assembly.

If I get a decent break from work today, I think I'm going to look up some replacement parts and cost. If the lead time is reasonable (which is long these days) and the price isn't more than half a new loco, then maybe I'll just buy some parts to see what happens.

I did take out another loco last night, a 4-8-2 Mountain steamer. It ran like a champ around the mainline without any cleaning - just put it on there and away she went. However, that loco is much too big to make the turns up to the mining area, so this little guy still has to work.

 

[D&J RailRoad]

I still think it's an issue with the wiper contact with the wheels.
Do you have a means of measuring current draw? That would tell you if something is an intermittent short.