Atlas N H-24-66 (Trainmaster) Exhaust Port Detail?

[tehachapifan]

Some time ago, I purchased a previously owned N scale SP Trainmaster knowing it had a possible decoder failure. Turns out, said failure melted the shell right where the exhaust port detail is on the roof. While the rest of the shell is magnificently rendered, it appears from the now deformed area that the exhaust ports may have been rather crudely rendered to begin with (two slightly raised rings with not even a slight depression in the center to represent the inside of the ports?). So, this may be an area I would've reworked anyway, but I can't even tell if the port rings were originally round or some other shape. Can someone with one of these locos take a look and let me know? A pic would be great too. Tried to find some proto photos online showing a roof view but had no luck. Thanks!

[Angus Shops]

I just plopped decoders into mine yesterday; the exhaust ports are round rings. Does yours have a high starting speed? I’ve tamed the high end speeds, but I can’t seem to get a satisfactory slow speed start.

[tehachapifan]

Thanks for the info on the port rings.

As far as starting speed goes, I haven't installed a replacement decoder in it yet. That said, I do expect to be able to fine-tune starting speed as it will be getting an ESU decoder. What decoder are you using? It might be a BEMF setting thing.

[Angus Shops]

Digitrax DN163A0. Available at LHS and cheap.

[tehachapifan]

You've tried adjusting CV2?

[Angus Shops]

Yes, I’ve messed around with CV2 but no drastic improvement. I took the decoders out of the 2 Trainmasters and put them in a
pair of True Line RS10’s (really an Atlas RS11 with a ‘Canadian’ shell) because I was more interested in getting the RS10’s into the DCC fleet. As an experiment I put the DC lightboards back in the TM’s and they ran fine at slow speed, so I’m assuming that means there’s yet another thing for me to learn about DCC. I’m a newb in the world of DCC. So far so good however.

Most of my loco fleet (all 30 pieces) is pretty new and has very low running time, and/or has been in storage for the last couple of years and I guessing  they need some running time before I can really tell what’s what.

[peteski]

Yes, I’ve messed around with CV2 but no drastic improvement. I took the decoders out of the 2 Trainmasters and put them in a
pair of True Line RS10’s (really an Atlas RS11 with a ‘Canadian’ shell) because I was more interested in getting the RS10’s into the DCC fleet. As an experiment I put the DC lightboards back in the TM’s and they ran fine at slow speed, so I’m assuming that means there’s yet another thing for me to learn about DCC. I’m a newb in the world of DCC. So far so good however.

Most of my loco fleet (all 30 pieces) is pretty new and has very low running time, and/or has been in storage for the last couple of years and I guessing  they need some running time before I can really tell what’s what.

You're correct - any running-quality issues in DCC should be addressed by first making sure the mechanism runs smoothly on DC.

What exactly is the problem with slow speeds?  Digitrax decoder, correct? Does the loco start moving (or at least can you hear the motor humming) at speed step 1?  Or the loco doesn't move until you are up several speed steps, then it lurches suddenly and the speed is higher than you would like?  Can you the turn the speed knob down few notches and that gets the loco running slower?

There are several variables involved.  BEMF settings are one such variable.  I believe Digitrax also has a kickstart variable to help in getting the stationary motor moving.

What CV2 settings have you tried? 

Yeah I know, all this should really be in a separate thread, in the DCC section. Maybe you could start one there to get some opinions from other "DCC heads".

[Angus Shops]

Thanks for the advice Peteski. However, seeing as I don’t currently have any decoders to reinstall in the Trainmasters, I’m going to put this particular issue aside and not fret about it for now. The same decoders worked perfectly in my RS 10’s, by the way. I’ve got LOTS of other stuff to keep me occupied…

Now back to your originally scheduled programming: What did we discover about the exhaust stacks on the Trainmasters? I found a couple of photos of CP units, and they do appear to have stacks that protrude maybe 10” above the top of the hood.

[tehachapifan]

....Now back to your originally scheduled programming: What did we discover about the exhaust stacks on the Trainmasters? I found a couple of photos of CP units, and they do appear to have stacks that protrude maybe 10” above the top of the hood.

I posted the question elsewhere and someone posted close-up topside pics of some SP units. On those, the exhaust ports are completely flush with the roof.

[Mark5]

Here's the Atlas model:
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I'm guessing that's the as built config (except for the "plugged" holes  ).

N&W rostered a large fleet of (merger inherited) Trainmasters.

The Wabash units were sent to Alco (by Wabash) to be re-powered with 251 motors and the roof looked like this:
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The Virginian units seemed to come to N&W (late 1959 merger) with short extensions:
https://www.nwhs.org/archivesdb/detail.php?ID=90332 (circa 1960)

N&W shops added at least two different kinds of extensions, one of which was huge - you see the smaller type in the photos on this web page:
https://wvrails.net/?p=85

Here is a pic of the larger type:
https://www.nwhs.org/archivesdb/detail.php?ID=154900

Thanks guys, looks like I have another project for when I'm not working my life way! 

Mark