Well, I just paid for my ScaleTrains SD40-2 Preorder

[GM50 4164]

Has anyone noticed on the motherboard that there appears to be a place to connect a keep alive? Looks like a TCS KA-N1 could be placed under the nose directly behind the class light glass.

[Jbub]

Has anyone noticed on the motherboard that there appears to be a place to connect a keep alive? Looks like a TCS KA-N1 could be placed under the nose directly behind the class light glass.

That would be cool. Since you have the shell off, take a look at the motor when it's running a low speed steps. I'm wondering if there is some binding that is causing the stutter.

[peteski]

Probably the reddit effect, where downvotes have become a "disagree" button.

Well, this is not reddit dammit!  It is TRW!   

[squirrelhunter]

My CSX is quite jerky at speed steps till 5 (of 28). The motor or gear hum is very audible with the sound turned off. Details look great and ditch lights are nicely done.

Sound is disappointing, I find IM SD40-2s to be a lot more clear and crisp, especially at higher RPMs. Dont know if the SD40-3 has a different sound file than the IMs.

With the exception of the truck detail and the ride height, IM SF40-2s are every bit as detailed as ST. Pulling power is quite low - struggles to pull 10 ESM & BLMA box cars on level track and 15 inch curves. The RI locomotive in the picture is an IM unit.

First wheelset on the front axle is out of guage. Not going to tinker, have to get ST take a look. Overall, not too impressed.

If IM would not use those terrible trucks, they would be really neck and neck with ST.

[kiwi_bnsf]

Hmmm, jerky low speed and struggles pulling. I'm curious if they had a batch of bad motors with these.

I don't have a ScaleTrains SD40-2 for comparison yet, but jerkiness at low speed and motor hum are definitely something I've encountered with my ScaleTrains Dash 9s. I was able to dramatically improve slow speed performance by tweaking the ESU BEMF motor control settings. The factory settings were too aggressive, and the auto-tune only made things worse.

I took quite a bit of trial and error, but the following work well with the Loksound V5 Micros in the Scale Trains Dash 9s:

Enable Back EMF  [CV49.0]

Basic settings:
    Regulation reference  [CV53] = 140   (14V)
    Regulation Parameter "K"  [CV54] = 30
    Regulation Parameter "I"  [CV55] = 20   (40ms)

Slow Speed settings:
    Regulation  [CV52] = 28
    Largest internal speed step that uses "K slow"  [CV51]  = 18
    Regulation influence during slow speed  [CV56]  = 255  (100%)

Back EMF settings:
    Slow Speed Back EMF sampling period  [CV116]  = 100  (10ms)
    Full Speed Back EMF sampling period  [CV117]  = 150  (15ms)
    Slow Speed Length of Measurement Gap  [CV118]  = 20  (2ms)
    Full Speed Length of Measurement Gap  [CV119]  = 25  (2.5ms)

PWM Motor pulse frequency  [CV9]  = 40  (40,000Hz)


These settings work well for me with a linear speed table optimised for a maximum scale speed of 60 mph:
    Minimum speed  [CV2] = 1  (0.39%)
    Maximum speed  [CV5]  = 78  (30.59%)

Hope this helps

It's possible/likely that the motor or drive train in the SD40-2s is a bit different, so I'll post an update once I finally get the chance to test with these.

As for the sound, Scaletrains hasn't figured out that cramming the largest speaker they can without a sound enclosure into the fuel tank results in a weak sounding locomotive. A properly sized and sealed enclosure produces exceptionally better sound than what they provide stock.

Yup — I agree 100%.

I'll be designing and 3D printing a replacement along the lines of what I created for my Dash 9s…

https://www.therailwire.net/forum/index.php?topic=56041.msg771205#msg771205

[kiwi_bnsf]

If IM would not use those terrible trucks, they would be really neck and neck with ST.

It's more that just the trucks that let the Intermountains down. There is a significant gap between the truck and the shell that ScaleTrains have done a great job of filling with under frame detailing. The Intermountain fuel tanks are also pretty crude.

Scale Trains have smaller diameter grabs and handrails, and their ditch lights are more accurate. They also pay more attention to road-number specific details.

[Jbub]

I don't have a ScaleTrains SD40-2 for comparison yet, but jerkiness at low speed and motor hum are definitely something I've encountered with my ScaleTrains Dash 9s. I was able to dramatically improve slow speed performance by tweaking the ESU BEMF motor control settings. The factory settings were too aggressive, and the auto-tune only made things worse.

I took quite a bit of trial and error, but the following work well with the Loksound V5 Micros in the Scale Trains Dash 9s:

Enable Back EMF  [CV49.0]

Basic settings:
    Regulation reference  [CV53] = 140   (14V)
    Regulation Parameter "K"  [CV54] = 30
    Regulation Parameter "I"  [CV55] = 20   (40ms)

Slow Speed settings:
    Regulation  [CV52] = 28
    Largest internal speed step that uses "K slow"  [CV51]  = 18
    Regulation influence during slow speed  [CV56]  = 255  (100%)

Back EMF settings:
    Slow Speed Back EMF sampling period  [CV116]  = 100  (10ms)
    Full Speed Back EMF sampling period  [CV117]  = 150  (15ms)
    Slow Speed Length of Measurement Gap  [CV118]  = 20  (2ms)
    Full Speed Length of Measurement Gap  [CV119]  = 25  (2.5ms)

PWM Motor pulse frequency  [CV9]  = 40  (40,000Hz)


These settings work well for me with a linear speed table optimised for a maximum scale speed of 60 mph:
    Minimum speed  [CV2] = 1  (0.39%)
    Maximum speed  [CV5]  = 78  (30.59%)

Hope this helps

It's possible/likely that the motor or drive train in the SD40-2s is a bit different, so I'll post an update once I finally get the chance to test with these.


Yup — I agree 100%.

I'll be designing and 3D printing a replacement along the lines of what I created for my Dash 9s…

https://www.therailwire.net/forum/index.php?topic=56041.msg771205#msg771205

Tim,
I appreciate all that you put into the hobby. Your contributions to sound enclosures and the above settings for the dash9 are incredible. When my CSX 40-3 gets here, I'll have to plug these values in to see what they do.

[squirrelhunter]

It's more that just the trucks that let the Intermountains down. There is a significant gap between the truck and the shell that ScaleTrains have done a great job of filling with under frame detailing. The Intermountain fuel tanks are also pretty crude.

Scale Trains have smaller diameter grabs and handrails, and their ditch lights are more accurate. They also pay more attention to road-number specific details.

But a big part of the gap below the walkway on the IM units is that the geometry of the trucks is such that there has to be an over scale gap- the problem is the top of the gearcase is higher than the top of the truck sideframes with makes the gear towers too tall which makes the chassis sit about 1mm too high, which make the walkways too high.

You can correct it partly by making the shell sit lower on the chassis by filing down the metal shelf in the fuel tank area the shell rests on, but you can't get the shell to the right ride height without new trucks. Underframe detailing just masks the problem with the IM units, if they had different trucks they wouldn't have the big gap to begin with.

My efforts to fix the ride height issue convinced me to dump all my IM SD40-2s since they always looked out of place next to any other Atlas locoas that have the right walkway height.

[C855B]

I bought four without sound, and just came back from the layout studio after installing an ESU LokPilot v5/E24 in one. Salient points:

• Detailing is off the charts. Very impressive.
• Decoder installation took 30-35 minutes. E24 connector is tiny and easily dislodged, so following the suggestion of securing with kapton tape is advisable.
• Most of the installation complexity is untangling the air line detail around the trucks while reinstalling the body. There are 8 of these, so if any of you remember the guy on the Ed Sullivan Show who spun plates on dowels, yeah, that's about right.
• MTL 1015 couplers are direct replacements if you are disinclined to use what ST provided. I prefer MTL TSC, and the short-shank is a drop-in replacement, and looks fabulous.
• With the LokPilot, it was incredibly smooth and the drive itself was silent. The only unintended audio was the growl characteristic of LokPilots at low speeds.
• Did I say it was very smooth? Oh. I did. Silky, and that's at a tie-to-tie walking pace on my not-just-cleaned track.
• I did not have time to test it under load. That will have to wait until tomorrow.

The ST SD40-2 that arrived in my mailbox this morning is a beautifully-rendered model, tracks well, runs very smoothly, is quiet, and is surprisingly tolerant of less-than-polished track.

But evidently, YMMV.  :shoulder-shrug:

[wazzou]

If IM would not use those terrible trucks, they would be really neck and neck with ST.

I mean…everyone is entitled to their opinions of course.
However, I’d bet if I polled 50 people that presently own or have owned both, I’d find that the results would not align with this.

[spookshow]

ST says that it looks like the fuel tank is installed improperly. But since I can't unscrew the fuel tank screws in order to fix it myself, I'm going to have to send it back to them.

-Mark

[wmcbride]

Tim,

You hit the nail right on its head. ST does not seem to grasp speakers. Thanks for all your work on enclosure design in other threads.

I know that when I buy a Scale Trains engine, it will be very detailed but adding decent sound will require a lot of work re: speaker overhaul and enclosure.

Atlas did such a good job with their gold and silver engines with the speakers in the fuel tank - the SD35s, for example, were great.

Bill McBride

[C855B]

7a. Pulling power - 20 cars (mixed 40' & 50') good on 1%; 2% doable with a running start and lots of wheel slip (I think I can I think I can I think I can!).

I suspect adding weight will improve this. Not a personal concern since I expect to run mine as a brace of four to recall UP's SuperVAN in its final days, their Super C expediter competitor.

[wmcbride]

My two arrived an hour ago. Beautiful models. Both run quietly and smoothly on straight DC and have good, slow speed operation.

Maybe the jerkiness others have reported may have been decoder related?

Mercifully, none of the crooked fuel tank issues reported by Spookshow.

They do seem a bit light but than again I had just been putting a gallon pf milk in the fridge.

My wallet certainly is a lot lighter since I bougth these.

[Bob]

My two CSX units arrived today - they ran perfectly right out of the box.  I think these are the nicest ST locos yet!  I'm impressed.