Atlas MP15 HELP!!

[Barobutt]

Almost a year ago today I decided to buy my self a NICE engine. Previously all I had was an undecorated lifelike engine with rapido couplers. I was thinking of getting into DCC so when I saw this wonderful engine at the 2nd hand shop I fell in love.



I was told it was a really nice atlas mp15 that the previous owner had put about $300 of custom work into. Custom paint, custom lighting (notice the strobe on the roof) and a DCC system. I was assured it would run smooth and fine on my DC track.

When I got the thing home it wouldn't run. When it detected power, the roof strobe would flash once but it wouldn't move. I took it back and asked what the heck was wrong with it. We determined that perhaps the DCC chip was set to not work on DC track, we'd have to find someone with a dcc controller and change the settings. So I left the train with him to fix.

A few months later I finally get the train back. He reports that the problem wasn't so easy to fix. Apparently the previous owner had stripped the firmware out of the DCC chip and put some crazy home-brew firmware on, then had to spend hours pooling all their friend's dcc know-how to get the thing back to default, but now it runs!

Horray!!! All I ever wanted was a smooth high quality switcher!

I get home and put it on the track, apply a tiny tiny bit of power expecting the thing to start at a crawl...

the damn thing rockets off at nearly full speed!!

This is not good. I set my power-back from full to pulse... no change. The engine's minimum speed is extremely high, not even the worse old bachman engine performed so poorly. I'm happy to finally see the damn thing move though. It also starts and stops on a dime. Goes from full speed to a stop instantly and doesn't handle the slightly bit of dirty track well. My cheap life-like engine coasts a little bit, think it's called "flywheel" ? This engine functions worse than my bachman....

I go back to the store I bought it from and report. He says he'll "look into it" and ask some friends but I have no idea what he could do. I doubt the guy purposefully sold me a lemon though, he's a nice guy and just acting as a middle-man.

I opened the thing up to take some pics in case you guys can tell me anything! I'm really desperate here. I either want to fix the thing, OR sell it on ebay and recoup what I can (I paid $70) but I don't want to sell it until I know what I'm dealing with for purposes of full disclosure.



PS this is the first time I've ever opened up a train and I don't know anything about anything, but I'm not seeing a DCC chip.. or is it buried inside the metal case?

[CaptOblivious]

Looks like the decoder is embedded in the cab. I don't know of any commercially available decoder (with a few notable exceptions coming from Europe) that can be loaded with custom firmware. I will assume that your dealer simply mis-spoke, and meant that it had been set up with some crazy combination of CV settings.

Do you have access to a DCC system? That's the only way we can make progress with this beast. Can you shine a light into the cab and try to get a good picture of the decoder, or read any markings on it?

Would be good to get a readout of all the CVs, if possible; if not, CVs 2--8 would suffice as a starting point. The value of CV 8 contains the manufacturer ID, and will thus tell us how to go about reseting it to factory settings.

[Barobutt]

Ok, I was just told that perhaps my problem is in the DCC's speed table. http://www.dccwiki.com/Speed_Table
But would that effect it's performance in DC mode?  

And as hard as I looked I couldn't find anything that looked like a chip or anything electronic looking inside the case.  Maybe I don't know what I'm looking for, but does anyone have a DCC mp15 and does it look like mine?  I know the wires going to the cab roof are custom, but apparently this engine came stock DCC.

And no, I don't have DCC.  That's why I had to wait months for the shop owner's friend to "fix" my engine so it would move at all...

[CaptOblivious]

Ok, I was just told that perhaps my problem is in the DCC's speed table. http://www.dccwiki.com/Speed_Table
But would that effect it's performance in DC mode? 

Yes, very much so!

[CaptOblivious]

Oh, and don't used pulse-power mode on your throttle with DCC decoders :D Might break them.

[CaptOblivious]

I guarantee you that your model does not have a factory-fitted decoder. If it did, it would look more like this on the inside:

[Barobutt]

Well then where the hell is my decoder?  When I sent this engine to be fixed after I bought it, they wouldn't have just taken the decoder out and said they fixed the problem knowing I'm running it on DC track?  If they had taken it out, would that explain the horrible performance I'm getting as the motor was designed to work with a DCC chip between it and the power source?

I didn't look too hard in the cab, but I think the only thing up there is the strobe, I don't think there would be enough room for a chip from the size of the one posted above, or do they make tiny ones?  I'll have to examine the cab more closely when I get home and maybe post some pics.

No one told me pulse ruined DCC chips... is that a sure thing or just a "may" damage it? I hope I haven't ruined my potentially non-existing DCC chip....


Looks like they DO make ridiculously tiny DCC decoders... maybe there is one stuff in the cab.

[CaptOblivious]

Pulse power "may" damage decoders. Depends on what the output looks like, and that can cary quite a lot; it also depends on the decoder's tolerance for non-DCC AC waveforms.

And yes, a Z2 would probably fit up in the cab :D There are bigger ones that would fit too (TCS M1 or Digitrax DZ125 might well fit up there too!)

[Barobutt]

Guys, thanks for all the help.  I've got 2 forums helping me now, both offering different pieces of the puzzle.  I was ready to just ebay this thing as a "potentially broken, as-is" loco at a huge loss but now I think it might be fixable.  I've always been into model railroading but I've never had much in the way of a network of people giving advise, I'd just figure things out my self as I went along.  This forum has been awesome in all things n scale, specially my new found interest in japanese trams of course.

I'm going to call the shop owner who sold this to me and get some more info and I'll report back.  The speed-table suggestion alone has really blown open the case.

[David]

Only 2 wires go into the cab, though there is some kind of extra wire up there (probably 2 LEDs and maybe a strobe circuit, but I can't see).

It I think I can be fairly confident in saying it's been converted back to DC, just without the benefit of the original lightboard, unless there is some really magic wiring involves (2 wires in isolated from each other but in the same jacket??).

What I see:
Faded Yellow and Purple (Dark Blue?) wire are soldered to the frame halves, providing power from the rails. Both of those wires have been split into 2 wires, with the heatshrink tubing around the split (purple becomes grey and yellow, faded yellow becomes light blue and orange). From there it gets a bit weird - it looks like the motor and front LED are sharing a wire (it's like they're run in series?), but it's hard to see from the picture. The yellow and blue split wires go into the cab.

Either way I do not see a decoder, and I do not see how any of this wiring could be from a decoder (track power directly to LED for example).

I have this particular model. It uses one of Atlas's fancy motors. I also have the original DC lightboard, I will check it to see if perhaps there is supposed to be some kind of resistor or other doohicky between the power and the motor. Though that weird LED+Motor in series wiring that the picture seems to suggest is equally bizare.

[CaptOblivious]

The wiring is rather odd. I wondered if they were using common-return on the LED, in which you wire the anode to
the blue wire on decoder, and the cathode to one of the rails (black or red wire).

There's a green wire in the cab that goes nowhere?

At any rate, the whole thing does look like quite a mess!

Also, presuming there is a decoder, the speed table may not be the only cause of your problems. I agree that it might simply be a messed-up speed table, but I've seen damaged decoders behave in the same way.

I am at a loss to explain the running behavior if there is no decoder, however. I can't imagine a way of wiring up the various bits in a decoderless loco so as to ensure top speed at small DC voltages. (Indeed, now that I think about it, I can't imagine a way of doing that with a decoder, either). Could you post a video of the suspect behavior? (And more, better-lit photos of the interior?)

[Barobutt]

UPDATE
So I called the owner and I told him what you guys told me.  First of all apparently the chip is "under the hood" in the shell and yes it still exists.  He didn't seem to think the speed table would be the issue because he said "we set it to dc mode" but when I told him people on !THE INTERNET! told me the speed table still does effect how it performs in DC mode he said for me to bring it down again and he'll get a friend to take it home and look into it and hopefully adjust the speed table.  He also said perhaps there's a faulty component and didn't outright say he'd replace it, but mentioned "we'll see about taking care of it".  

[CaptOblivious]

DO NOT SEND IT BACK TO THIS SHOP! I am quite sure they are screwing you.

I am now inclined to agree with David's analysis that there is no decoder in there. Photo to follow.

[CaptOblivious]

Here is a photo in which I tried to trace the wires to show common connections. The original author of this rat's nest didn't use wire colors consistently at all. I caution that, outside of concrete continuity-check evidence that this is just a hypothesis. But it looks like the motor, headlight, and strobe are wired in parallel, and in parallel with the track—exactly how a DC loco is wired up.

HOWEVER, there might be a decoder hidden inside the frame just above the motor. The wires all get jumbled together at that point, and what I'm identifying as a junction at the motor tabs might actually be seperate wires from a decoder hiding in there.

Grain of salt and all that.

But I'm telling you, this store you're dealing with? They're not being straight with you.

[Barobutt]

Really doesn't seem in this guy's nature to do something like that.  He's bent over backwards for me in the past fixing other people's stuff, given me free replacement parts and replaced a bunch of couplers for me that he even gave to me for free.  HATES N scale but he sat there for a good 30 min chatting with me while occasionally swearing in frustration at how tiny N scale is as he worked on my rolling stock.  He's an old friendly hippie with a big gray braided beard who won't carry anything military related in his store as it's against his personal morals.  I'd believe a mix up and bad photography before I thought the guy was trying to scam me.  And even if he was, if he finally fixes the damn thing I'm happy.

[David]

This is what I came up with.

Like Don the only possiblity I have for a decoder is that it just below the orange shrink wrap - is that a circuit board there, or a flat black surface? Even if it is a decoder the LEDs don't seem to be connected to, unless there is a really weird job under that heatshrink.

[Barobutt]

Haha this is such a crazy mystery, I'm almost more interested in this as a "who done it" than actually fixing my train.  Very curious!  You guys are good detectives!  I wish I had even one of you guys here to actually examine my train.  I'd picture you all with Sherlock Holmes caps and magnifying glasses getting to the bottom of this.

[David]

Really doesn't seem in this guy's nature to do something like that.  He's bent over backwards for me in the past fixing other people's stuff, given me free replacement parts and replaced a bunch of couplers for me that he even gave to me for free.  HATES N scale but he sat there for a good 30 min chatting with me while occasionally swearing in frustration at how tiny N scale is as he worked on my rolling stock.  He's an old friendly hippie with a big gray braided beard who won't carry anything military related in his store as it's against his personal morals.  I'd believe a mix up and bad photography before I thought the guy was trying to scam me.  And even if he was, if he finally fixes the damn thing I'm happy.

I wouldn't accuse him of 'scamming' you. He may just not know much about what he talking about in this case (homemade decoder firmware?). There are plenty of people of guys in model railroading for whom DCC just means 'something complex under the hood that I don't want to know about'.

[David]

Also, based on my diagram/guess - what happens when you try to run the locomotive in reverse?. Does it move, do any of the lights come on?

[CaptOblivious]

This is what I came up with.

Like Don the only possiblity I have for a decoder is that it just below the orange shrink wrap - is that a circuit board there, or a flat black surface? Even if it is a decoder the LEDs don't seem to be connected to, unless there is a really weird job under that heatshrink.

Yeah, the strobe is clearly wired to the rail/motor. But it looks to me like the headlight could conceivably be wired to the function leads of a decoder inside the frame—Look at the wire coming off the resistor. It might wind under the blue wire, and into the red shrink wrap. OR, it could be that it disappears under the blue wire headed to the cab; and a different wire is going to the red shrinkwrap. Evidence: On the right of the blue wire, it looks white; on the left it looks gray. White wire might or might not be soldered to the motor tab. The blue wire from the LED does clearly seem to dissappear into the frame, where it might or might not be soldered to the motor tab. If this hypothesis is right, it has the advantage that the proper colored wires are being used: White/blue to LED, orange/gray to motor…yeah, nevermind, that can't be right, because the motor really does look clearly wired to the rails, and that isn't proper wiring for a DCC installation at all.

Hrm.

I wouldn't accuse him of 'scamming' you. He may just not know much about what he talking about in this case (homemade decoder firmware?). There are plenty of people of guys in model railroading for whom DCC just means 'something complex under the hood that I don't want to know about'.

Again, I'm inclined to agree. Not that it's a scam, but this guy is representing himself as knowing more than he does. Or his friend.

Getting to the bottom of this will require a continuity checker for sure, a willingness to crack this baby open, and if at all possible a DCC system…

[CaptOblivious]

Haha this is such a crazy mystery, I'm almost more interested in this as a "who done it" than actually fixing my train.  Very curious!  You guys are good detectives!  I wish I had even one of you guys here to actually examine my train.  I'd picture you all with Sherlock Holmes caps and magnifying glasses getting to the bottom of this.

This is fun!

[Barobutt]

Yeah, I trust him when he says he took it to one of his regular's with N scale DCC and the worked on it.  I can't remember the specifics but basically they had to put in a couple hours time to figure out what the heck was going on because he says it was a very unusual setup.  He didn't tell me this as a sob-story, he in fact said him and his friend had a blast solving the mystery and figuring out what the hell was going on inside.  Maybe his friend "fixed" it by taking the decoder out and then they tried to re-wire the strobe and couldn't...  he mentioned when he gave it back to me that they couldn't get the strobe to work in DC mode but it should still work when I upgraded to DCC.  But if that was the case he's the type of guy that would have said "Sorry dude, to get it to run on DC track we had to take the decoder out, we tried to re-wire the strobe but it doesn't work.  Here's your decoder, when you upgrade to dcc we can put it back in".  I even told him when I gave it to him that I'd be fine if they just took the chip out but he said it wouldn't come to that.

[CaptOblivious]

Also, based on my diagram/guess - what happens when you try to run the locomotive in reverse?. Does it move, do any of the lights come on?

Dammit, David, you are not allowed to suggest clever, simple tests like that. If David is right, and there is no decoder and everything is wired as our diagrams suggest, then if you ran the thing backwards, the headlight won't light. Which would pretty much either nail his hypothesis, or indicate that the decoder was programmed to turn the headlight off in reverse. Which is often the default behavior. But if it remains on, we know we've got a deocder in there somewhere… (LEDs are polarized devices; they light when voltage is applied one way, but not the other)

[Barobutt]

I'm not at home at the moment so I can't run any tests.  The moment I get home though I'm going to test as you say and take some better pics with a flashlight and identify every wire.



Here's a quick picture I made.  I'm mostly interested in that mystery wire in the cab.  The train does run forward and backwards fine but at the exact same wayyyy too fast minimum speeds.  The strobe never works, and I can't remember if the lights stay on or not.  One thing I did notice is that the lights stayed at an almost totally consistent level of brightness regardless of the power applied, contrasting to my life-like engine that's light dim or get brighter as you apply power.

[CaptOblivious]

Green wire in cab is indeed quite the mystery. As is the Kapton tape on the frame under the cab (the yellow-orangish tape); it's usually used in decoder installs to electrically isolate bare metal, but it's not at all clear what's being isolated from the frame.

The two "prongs" coming off the resistor just looks like a sloppy soldering job to me.

And if there is a decoder, it probably is hiding here you ask if something could be hiding in there.

Incidentally, LEDs have the interesting property of appearing to have a fairly constant brightness over a range of voltages, so your description of the headlight isn't surprising, nor is it evidence for any of our hypotheses, sadly.

[inobu]

It drives me crazy when people tell others that you can run both DC and DCC. The truth is you really need to know what you have in order to do it. Not all decoders and command /boosters operate the same. Although there are standards not all systems are alike.

Also running DCC/DC so called zero stretching is stressful on the motor and I would not do it............... with that said.

Baro,

I'm seeing a few things like the others

you need to be careful of running your unit until you find out what you have. The top of the cab seems to be melting. The plastic is discolored.

Also the wiring does not make sense all the tapping of wires is making a rats nest of problems (you already know). I think that he has your LED wire tapped to the motor
block and that is why you are getting the full throttle when the power is applied. The decoder output for a LED maybe tapped and feeding the motor.

If this was a true DCC / DC decoder the chassis would have to be isolated from the pickups. The decoder would feed the motor leads just the same.  

If you values that unit, I would remove all the DCC stuff or have someone with skill to redo it for you. Who ever had it last did not clean it up that for sure.

The neater the install the better off you will be.

Inobu
 

 

[inobu]

Haha this is such a crazy mystery, I'm almost more interested in this as a "who done it" than actually fixing my train.  Very curious!  You guys are good detectives!  I wish I had even one of you guys here to actually examine my train.  I'd picture you all with Sherlock Holmes caps and magnifying glasses getting to the bottom of this.

This is fun!

LOL ...to you. Always fun to operate on someone else. LOL

Baro, Don't worry we will help you get to the bottom of this.

[CaptOblivious]

you need to be careful of running your unit until you find out what you have. The top of the cab seems to be melting. The plastic is discolored.

You know, I thought the horns looked like they might be drooping in the second photo compared to the first. Is that so? Is there something melting? That would be very bad, and would I second Inobu's advice.

[Barobutt]

Ah no the discoloration on the top is some damage from solvent glue.  Out of all the fleet of engines and rolling stock by this guy they were all in the 150-200 range except for this loco which was "only" about 68 due to the glue damage on the roof.  I'm just going to sand it down and re-paint the roof, easy.  it's the one issue with this loco I CAN fix.

[Barobutt]

So I just opened up the engine again now that I know what I'm looking for....



I'm mad!!  Mystery wire? Doesn't go anywhere.  There's in fact 4 wires in the cab, only 2 conect to anything.  There's no DCC decoder anywhere, most of those bits of tape are hiding useless wires.
I took a bunch of pictures as evidence, I'll post them soon but I want to go down to the store RIGHT NOW.  I took a video too showing it's ~100mph minimum scale speed and the lack of light when moving backwards.

[CaptOblivious]

Woah there, Tex. You've probably got excellent reason to be angry, but let's have a look at your photos first just to make sure you don't do something you'll feel silly about later. Better to dobule check first, then start shooting ;)

[Barobutt]

https://lh3.googleusercontent.com/_cW2l8ppIEZA/TZOtQ-B4VXI/AAAAAAAACs8/eks-qgZ8_Gg/s576/100_1195.JPG
Not the best shot but look inside, you can see the blue wire splits into two.  This isn't in fact a split, but a dead-end wire taped up to it.


Slightly better focus of the two blue wires.

Nothing hiding on top of the motor, it's hard to tell but to the human eye it's clear that's all motor.

Another attempt at getting a good shot inside the cap.  There's only the 2 lights in there, cab light and strobe.  The brownish wire doesn't go anywhere, in person you can see the metal tip of the wire.  I believe the blue wire and brown wire were connected to the strobe at one point.

I'm uploading the video now but it's taking FOREVER despite being only 28 megs.  It shows the train going super fast at minimum speed and the front lights not coming on when reversing.
Here's a link to my album so you can view larger resolution images https://picasaweb.google.com/107575807634177808838/Trains#

https://picasaweb.google.com/lh/photo/S0aTT7GmRU6SA1eKOuCcRg?feat=directlink VIDEO

Ok, I'm heading to the shop in about 15 min unless anyone replies with some revolutionary suggestions or evidence.

*15 min later*
Ok guys I'm off, wish me luck.  I have no idea how this is going to go down, I'd prefer to keep a good relationship with this guy as I actually like him and his store so I'm willing to buy the lamest excuse so long as I get a refund or a true fix.

[CaptOblivious]

Yeah, there doesn't seem to be anything in there. Give 'em hell.

[Barobutt]

TRIP REPORT
I arrive and I explain the problem with its shitty performance.  he says that this is sold as a switching loco so there's no excuse for it running how it is.  He just asks me to hand it over and he'll take care of it by investigating the speed profile.  I said that might be hard as I'm not sure there's a DCC decoder in there.  He just laughs as says yes there is, in fact it's a really nice 4 function decoder that's a bit smaller than a normal one so maybe I missed it.  I open it up and show him.  He's pretty confused as to where the heck it is.  He examines the cut and taped wires and seems a bit upset.  He apologizes and says he told his friend that I wanted this to run on DC track, so to switch the decoder's DC function ON, nothing about taking the decoder out.  He seems a bit mad too that even if the guy did take it out, he should have given it back as it's about a $45 decoder.  He searches online for a while for replacements and we're still shocked at why it runs so poorly in DC mode.  He says bottom line, he'll make things right, but in the mean time let's try to figure out why it's running poorly.

Motor is stock, gearing is stock.  He sets up a test track and runs it, it runs just like on mine, maybe a tiny bit slower.  He switches to pulse and it runs almost ok, but still way worse than my bachman and he agrees that's no way for a switching loco to run.  We realize he actually has a brand new unopened mp15dc DC version so we open it up to check if there's some board or something inside that might effect it's speed.. nope.  We test it out on the track.  IT RUNS JUST LIKE MINE!!

What the hell atlas??  This confuses him even more, "Why would they sell a switching engine that runs like this, atlas is top of the line, I've sold many of these as DC switchers and never heard a complaint..".  We switch to pulse mode and it runs a lot slower, but still very jerky.  But either way, the two loco's run identically horrible.

I subtly float the idea of taking it back for store-credit or a trade for another loco but he says it's "too late" for that.  He says "if you had come to me within the first couple weeks I could have given your money back but it's way too late for that now".  That rubs me the wrong way because the only reason it's been so long is that he's been either promising to fix the engine or waiting for a friend to fix it for all those months.  I only had the damn thing in my possession for about a week and only had it on track out of it's box for about 10 min.  But I can understand his position because he's just the middle man.  The owner has already been paid long ago.  He's also just the middle-man for his friend who's basically stolen my $45 decoder.

I make it very clear I don't just want this engine to run on DC.  I plan on upgrading to DCC soon and he sold this engine to me as a great deal at $70 because it has a 4 function decoder and will run fine on DC track.  At the moment it does neither.

He currently has the engine and is contacting his friend to try to get the chip back, otherwise we'll get a new 4 function chip.  I'm sure as hell not paying $45 for it though if it comes to that, and they better solder up all the wires again too.  I understand it's not his fault his friend took the chip, but it was in his possession to be serviced and it's not my problem, that's part of the cost of running a business.

Overall I'm not mad at him.  I'd have liked him to offer a refund or store credit, or make it more clear from the start that no matter what he'll do what it takes to make this the engine I paid for but I understand he's trying to run a business.

My plan once I get the engine back with a working 4 function decoder? Ebay the damn thing or trade it with a friend.  Even if I lose a little money on it I want rid of the thing, it's been nothing but problems.

[Shashinka]

That would get me pretty cheesed as well. But at least we now know there is clearly a problem with the engine and that the shop has been jerking ya around.

[Barobutt]

If any of you have a MP15, does it run how mine does in the video? Take into account that's on FULL not PULSE.  Did atlas release a bad batch of these or are they all so jerky and fast?  I don't understand why both mine and the brand new out of the box one ran exactly the same, ie garbage.

[inobu]

There are too many changes made from the original install to come to a sound conclusion. Looking at the third group of pictures it looks like it is the results of the decoder removal, hence the extra wires. I find it hard to believe that the decoder is in the heat shrink based on the gauge of the wires coming out. So we can forget about the decoder

Entry 21 makes it hard to determine if the decoder is still installed or wired in the motor casing. So I going to the speed problem.

I'm a little perplexed about the speed problem but logic states if this is a plain DC configuration with no decoder then the excessive speed is from the controller. If he still has the controller set to pulse at the voltage setting is high along with the duty cycle then that is the culprit. DC speed is based on voltage and there is nothing in the cab that will step up the voltage so the only other possibility is the DC controller.

Boy I had to strike everything out. LOL

I am going to find the problem...!!!!!

This is fun ...

Inobu

Inobu

 

[keitaro]

you're pretty forgiving i would have grinded the guy.

anyway thats some awfully messy wiring for a now stock loco.

[inobu]

You problem is in the motor.

Atlas has a Fast Speed motor, Slow speed and Scale speed motor. There has to be an issue with the motor if the New unit (NIB) did the same thing.

You might need the DCC decoders to manage the speed and that may be why the original installed the decoder. 

Inobu

[CaptOblivious]

Don't let that third party touch your loco again. Get your money back. I wouldn't trust him at all.

Get yourself one of these:
http://www.digitrax.com/prd_mobdec_dn163a3.php
or one of these:
http://www.tcsdcc.com/public_html/Customer_Content/Installation_Pictures/N_Scale/Atlas/MP-15N/MP-15N.htm

And do it yourself. You've been through hell with this, no sense in making it worse by relying on known unreliable elements.

Or, hell, send it to me, and I'll do it for the cost of return shipping. Stories like yours just make me livid.

[CaptOblivious]

You problem is in the motor.

Atlas has a Fast Speed motor, Slow speed and Scale speed motor. There has to be an issue with the motor if the New unit (NIB) did the same thing.

You might need the DCC decoders to manage the speed and that may be why the original installed the decoder.  

Inobu

Are the motors interchangeable? No amount of DCC magic is going to make this loco run slow and smooth, if it can't be achieved with a quality pulse-power DC throttle. 'Cause they both work in just the same way…

Update: The Atlas product page says it comes fitted with the "Scale Speed" motor. Funny definition of "scale speed" they're using?
http://www.atlasrr.com/nloco/nmp15.htm

More: Spookshow reviews the motor's performance as quite good, and he's known for not accepting lousy quality product:
http://www.visi.com/~spookshow/atlasmp15dc.html


Finally, might consider replacing the motor, and seeing if that helps:
Atlas part no. 522100
https://secure.atlasrr.com/mod1/itemdesc.asp?ic=522100&eq=&Tp=

[inobu]

The decoder makes it tunable. You can fine tune the speed tables which gives you more control. Based on the results from the NIB unit one can conclude that these unit require some kind of speed management.

The problem is we don't know if the original motor has been changed out and the decoder was installed to compensate/manage the speed for it.

Inobu

[Barobutt]

I'm not good at being confrontational, but I did make my case clear I think.  If this isn't fixed and running how I'd like I'm going to do my best to be more aggressive... or just bring my wife who doesn't take shit from ANYONE to back me up.  I'm grew up in a very calm polite Canadian city known for its retirement communities, she's from Moscow....

[CaptOblivious]

The decoder makes it tunable. You can fine tune the speed tables which gives you more control. Based on the results from the NIB unit one can conclude that these unit require some kind of speed management.

The problem is we don't know if the original motor has been changed out and the decoder was installed to compensate/manage the speed for it.

Inobu

A decoder's output on the motor leads is just a 12V (give or take) PWM signal, which is going to be awfully similar to many good throttles. If he's got a good pulse power throttle, and can't make it run slow, then no tweaking of decoder settings will get it to run slow either.

[Barobutt]

yeah that was my theory as well.  My throttle is an oldie but it's huge and feels quite quality.  All my other locos I can control from a crawl.

Nothing makes sense!!

[inobu]

A decoder's output on the motor leads is just a 12V (give or take) PWM signal, which is going to be awfully similar to many good throttles. If he's got a good pulse power throttle, and can't make it run slow, then no tweaking of decoder settings will get it to run slow either.

I'm able to get my unit to run at 1mph no stalling. The only way to get that is to change your speed steps and correlate your throttle position. The decoders have PID control and uses Back-EMF to control motor speed. Hard to do that with a DC controller it is just pulse duration and whatever the scale on the pod.

Inobu

[CaptOblivious]

A decoder's output on the motor leads is just a 12V (give or take) PWM signal, which is going to be awfully similar to many good throttles. If he's got a good pulse power throttle, and can't make it run slow, then no tweaking of decoder settings will get it to run slow either.

I'm able to get my unit to run at 1mph no stalling. The only way to get that is to change your speed steps and correlate your throttle position. The decoders have PID control and uses Back-EMF to control motor speed. Hard to do that with a DC controller it is just pulse duration and whatever the scale on the pod.

Inobu

Fair enough. You speak the truth. Still, I would think that, having just watched the video, something is badly up with this motor that is not going to be easily remedied with just a decoder. I think a full remedy is going to involve replacing at least some if not all of the drive train with new, known-good parts. Which thankfully doesn't look too expensive.

The mystery remains, however, of how it came to be this way, and why the stock unit on the shelf behaved in the same way…

[inobu]

Yeah,

I think that the NIB unit speaks a lot in that the unit need something done to it. If it is gearing or speed control. We will see. I almost want to get one just to see what in the heck is going on.

Inobu

[CaptOblivious]

That's just it, though. EVERY review of this loco praises its butterysmooth low speed action. There is no reason for a NIB one to drive badly. But it did.

Paranoid conspiracy theory that is false: unless the proprietor was remotoring his stock with cheap motors, and selling the nice motors harvested for a profit in ebay!

[keitaro]

maybe it was his "mate" who changed the motor hahaha hence the dodgy wiring