Loksound 73100 in an N Atlas MP15DC

[tehachapifan]

I tried running it on the Digitrax Zephyr and a DT 400 throttle which displays which functions are on so I could verify drive hold was on /off.....

Not too beat this horse too much, but my controller also displays what functions are activated and I've had nothing displayed on the controller when Drive Hold was actually active in the decoder. I'm not exactly sure why this happens, but I've had a few engines that wouldn't run when I first put them on the layout or fired them up for the first time during a new op session until I activated F9 (Drive Hold on mine), then hit it again back to off.

...also, any chance the loco has a consist address active? Sorry if you covered this one.

[Jbub]

Haven't really read every post but what about the engine brake function? The logo won't move if that is activated iirc

[Jim Starbuck]

Thanks guys. I appreciate your suggestions.
Drive hold and engine brake are off because the decoder will run the motor on the tester.
This is a new decoder and has not been consisted with anything. Good point though. I’ve had to fix that on someone else’s engine before.
I made no other changes than to simply move the wires from the tester to the locomotive and track power from the tester to the track the loco is on.
Is there some type of feedback the decoder needs but isn’t getting from the motor in the loco?

[cbroughton67]

Jim,
Have you checked the decoder's speed step setting? I seem to remember a setting for it in the programmer software. I don't believe I saw that mentioned. Digitrax expects 28/128 by default, unless it has been changed.

Have you tried running the locomotive with decoder installed using the programmer itself with the "Driver's Cab" feature in the programmer software? Or is this the "tester" you're referring to and not a separate device?

Chris

[Jim Starbuck]

Thanks Chris,
I unchecked “Detect speed step automatically” and selected 28 or 128.
No change
I’ve tried using Driver’s Cab in Lokprogrammer 4.7.2 and 5.0.2. And also stand alone Digitrax Zephyr with and without a DT400 throttle.

The Loktester is a separate device built by ESU for testing decoders. It has an onboard motor, lights, speaker and all the assorted plug types plus a bank to connect individual wires.

One thing I have noticed in all The programming attempts is in the load control menu when I pick any motor type (even default settings) then write them when I go back to read it no motor type stays selected.

I’m going to set this aside until the new decoder arrives.

[peteski]

Have you tried to measure the resistance across the motor's terminals (with the decoder disconnected).   Hook up an ohmmeter and watch it as you slowly spin the motor shaft. Just curious . . .

[Jim Starbuck]

Ah, I see where you’re going Peteski.
Let’s gauge the health of the motor. Good call.
I removed the decoder and went back to DC before taking the mech apart and took some track voltages.
The mech would consistently start in either direction at 1.5-1.55 volts. A nice steady ~10-15 smph would be at 2.6-2.7 volts. 12 volts and it was a racetrack.

Then I disassembled and checked resistance with just the motor a few times.
Lows when turning the shaft slowly were 12-13 ohms and highs were around 35-37.
The average window would fluctuate between 17 and 25 ohms.

I don’t know what’s normal for a motor. Do these readings tell you anything?

Thanks,
Jim

[peteski]

Then I disassembled and checked resistance with just the motor a few times.
Lows when turning the shaft slowly were 12-13 ohms and highs were around 35-37.
The average window would fluctuate between 17 and 25 ohms.

I don’t know what’s normal for a motor. Do these readings tell you anything?

Thanks,
Jim

While I don't have that model, I have some of those motors I bought on eBay for couple of bucks each.  They look identical to the one Atlas uses.  The resistance and performance readings I see are pretty much like the ones you see.  So I have to conclude that the motor is healthy.

Next, check the same parameters for the motor in your ESU the decoder tester. I wonder how different they are?

[tehachapifan]

I think I recall something about these particular motors not having the typical brush arrangement and instead uses (brass?) "fingers" of some type. If this is indeed true, could this show normal readings but still cause an issue with the motor?

[peteski]

I think I recall something about these particular motors not having the typical brush arrangement and instead uses (brass?) "fingers" of some type. If this is indeed true, could this show normal readings but still cause an issue with the motor?

Brushes are brushes, regardless of whether they are made form metal or carbon.  Pretty much all coreless motors have (often precious) metal brushes.  But there's something strange going on here - not question about it.

[Jim Starbuck]

Well I think I finally got to the bottom of this little mystery.
The problem is in fact the motor.  I had it connected to the decoder and holding the motor I noticed it would try to turn ever so slightly. Close inspection revealed some white corrosion in one of the vent holes. Figured I had nothing to lose so I shot plastic safe contact cleaner into the vent. Blew it out then ran the motor on a 9v. While it was running something made a slight “tick” inside and it sped up about a third faster than it had been running. I ran it like that for a few minutes changing direction a couple times. I then connected the motor leads to the decoder and sure enough, it ran. It still had a slight catch in it occasionally but not enough to stall it.
I assembled the mech with the decoder in it and on the track it moved about a quarter inch then stalled.
At least I know what the problem is now.
I’m going to replace the motor when I find one. These little closed motors don’t lend themselves to disassembly very well. Tabs on the metal case bend down to hold the end plate on.

Anyway, the whole point of this was to install a Loksound 73100 in an MP15 and that part all worked well.

[peteski]

Well I think I finally got to the bottom of this little mystery.
The problem is in fact the motor.  I had it connected to the decoder and holding the motor I noticed it would try to turn ever so slightly. Close inspection revealed some white corrosion in one of the vent holes. Figured I had nothing to lose so I shot plastic safe contact cleaner into the vent. Blew it out then ran the motor on a 9v. While it was running something made a slight “tick” inside and it sped up about a third faster than it had been running. I ran it like that for a few minutes changing direction a couple times. I then connected the motor leads to the decoder and sure enough, it ran. It still had a slight catch in it occasionally but not enough to stall it.
I assembled the mech with the decoder in it and on the track it moved about a quarter inch then stalled.
At least I know what the problem is now.
I’m going to replace the motor when I find one. These little closed motors don’t lend themselves to disassembly very well. Tabs on the metal case bend down to hold the end plate on.

Anyway, the whole point of this was to install a Loksound 73100 in an MP15 and that part all worked well.

Interesting . . .

Motors like that one are on eBay (as discussed in the Motorman thread)..
https://www.ebay.com/itm/DC-12V-17800RPM-High-Speed-Dual-Shaft-Mini-N20-Motor-For-Toy-Car-Boat-Model-DIY/263945470739

Use the best offer feature and offer $1.01 for the motor (if you get multiples, like ten of them).  At less than $11 you will have 9 spares.  Can't beat that.

[Jim Starbuck]

I finally had success on my install.
Turns out the motor was somehow shorted internally. Possibly carbon bridging the commutator segments?
I bought a cool little gear puller off eBay (thanks Chris 333) which let me pull a flywheel and get the motor case apart. I was wrong earlier, these closed case motors aren’t hard to get apart, just bend the little tabs up and pull the case off.
I cleaned the commutator with plastic safe contact cleaner and made sure the brass fingers were aligned and it took off and ran well. Earlier I had noted there was continuity between the motor leads. That right there should have told me the motor was shorted. There isn’t continuity there now.
The fact that this thing would run on DC and also the stock Lenz decoder is still a complete mystery however.
Anyway it seems the gremlins are chased out of it so now it’s on to wiring the lights and caps before painting the shell.
Again, thanks for all the input and help here.

Jim

[peteski]

Thanks for posting the followup, and great to hear that you were able to fix the problem.

Not sure what you mean that there was continuity between the motor terminals.  You mean your multimeter was beeping on the continuity range indicating "continuity"?  The motor is just bunch of copper wire, so it has a fairly low static internal resistance. Actually the readings you posted earlier (12-37 ohms).  That was similar to the motor I bought from eBay (and didn't seem to be abnormally low to me).

Either way, you have fixed the problem. Did you happen to take the motor's resistance reading after you serviced it?

I suppose that it is possible that if the motor's internal resistance was low enough, maybe the ESU decoder was sensing that and shutting down the motor driving circuit.   In DC and with the old Lenz decoder (which might not have a sensitive motor driver protection circuit), maybe whatever conductive particles were creating low resistance between the commutator segments were simply getting burned off and the motor would run.  Just guessing . . .

[Jim Starbuck]

Loksound 73100 install v2.0

I revisited the sound install in the Atlas MP15DC.
My first attempt worked ok but I wasn’t totally happy with the results still thinking it could / should be better.
The stock motor was balking again and I have a direct replacement for it but as long as I was going to replace the motor, why not improve it?
I replaced the stock motor with a slim coreless from a Bachmann S4. This is the same motor I have used in other install projects.
A couple advantages to the slim motor became evident. While being smoother and quieter than the stock motor, it also allowed room to mill some small bits from the chassis lowering the 73100 to set right on top of the main part of the chassis. The rear of the decoder protrudes into the cab and interfered with the speaker enclosure before. Now with the decoder lower, the enclosure can reside above in the cab.
I used the stock worms and made the shaft coupling from styrene tube. The motor end of the tube has a brass bushing pressed in stepping the bore down from the 1.5 mm worm shaft diameter to the 1 mm motor shaft. The motor was stabilized by gluing a wafer of .020 styrene to the bottom which is then sandwiched between the frame halves in the fuel tank area.

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I milled out the area shown in black.

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I was hoping there would be enough room above the decoder for case size 4 caps but there isn’t. I’m going to slot the styrene piece below the motor and I think there is room for a couple caps under there. We’ll see.
Lighting will be done with 0603 LEDs.

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I’m satisfied with the way this runs and sounds now so it’s time to start working on the Skytop Models conversion shell and front sill mods.

Jim