Atlas GP38 motor

[gbcaboose]

I recently purchased a preowned Atlas DCC ready GP38. I opened it up to install a decoder and found that the motor tabs aren't like previous Atlas GP38/40's that I've installed decoders in. This one has a motor tab at the top and another at the bottom. The bottom tab is short and contacts the frame. There's no way it could reach and contact the decoder.

The motor appears to be from an older non-DCC ready locomotive that didn't have the full length light bar. Before I contact the seller, does anyone know it Atlas ever sold this this of motor/tab set up in the DCC ready frame, or has the motor been swapped.
 

[davefoxx]

Sounds like the entire mechanism was swapped, which could have been done to turn a non-DCC unit into a DCC locomotive.  They then put the old mechanism under the shell that you bought, and, voila!  Which Atlas GP38 did you purchase?  You can figure out its release on Atlas' website, and then it can be determined if your locomotive has been altered.

DFF

[gbcaboose]

It's a GP38 (no -2). I think all the GP38's are DCC ready. It's just odd that the frame is DCC ready, but it appears the motor has been swapped.

Mike

[peteski]

This Web page might be helpful in identifying things. http://spookshow.net/loco/atlasgp3840.html

[rrjim1]

Hard to see in the picture but it looks like the motor was replaced with an older Atlas slow speed motor.

[jjb62556]

that frame in the picture is not DCC ready for a drop in board.  TCS CN-GP decoder will work.

[mu26aeh]

I've never seen an Atlas motor that has a short tab on top and bottom, the bottom one always wraps around the side of the motor.  Maybe someone for some unknown reason cut the bottom tab to match the top ? 

[tehachapifan]

Yep, someone did the ol' switcharoo. Motors with short tabs on the bottom and top are from the era prior to DCC-ready frames. You'll see this from time-to-time with previously-owned things marketed as DCC ready. The problem is, the previous owner might not have been the one to do it, if they run DC only, and may have purchased it used as well.

...edit to my above....someone else mentioned that is not a DCC=ready frame. I'm having a hard time telling if that's true at the moment. It sort of does look DCC-ready to me. Either way, the whole drive or motor got swapped...if it was indeed supposed to be a DCC-ready unit to begin with.

[SkipGear]

No expert here but I thought that the black motors were pre-DCC ready frame. That is a black motor in a DCC ready frame from what I can see. Can you show a picture of the light board, if there was one?

[Bendtracker1]

That chassis is a DCC ready chassis.
You can tell by the notches on the corners towards the upper middle of the frame.
The motor is a DC motor, my guess it would be from a first run GP40 or similar pre DCC chassis.
Black housings were used for High Speed motors before DCC.
There was an era at the beginning where a few slow speed motors came with Black Plastic, but soon afterwards they switched to gray plastic.
Once the High speed motors were phased out, they returned to using Black plastic housings again.

[gbcaboose]

It came with the standard looking Atlas lightboard, although nothing was contacting the two pads near the center where the motor tabs would normally contact the board.

I'm thinking of trying to solder a phos/bronze extension on the bottom tab and bending it upward to contact the board. I would have to keep it isolated with kapton tape. If I can get it to work with the stock Atlas board, I should be able to install a Digitrax drop in decoder. I'm assuming the the only reason the motor is not DCC friendly is the location of the motor tabs. Is there any other reason this wouldn't work?

Mike

[Bendtracker1]

Don't see a reason why that wouldn't work.  As you said, just be careful to keep things insulated.
If the motor would happen to run backwards after you've got things soldered up, you can always go in and change the
settings in CV29 for reverse running.

[peteski]

Don't see a reason why that wouldn't work.  As you said, just be careful to keep things insulated.
If the motor would happen to run backwards after you've got things soldered up, you can always go in and change the
settings in CV29 for reverse running.

Changing CV29 will not fix the problem.  This is a common misconception.   The direction bit in CV29 is to reverse the direction for all the functions.  So while the motor will appear to run correctly, the headlights will be reversed (again).

[tehachapifan]

But then the lights can (typically) be corrected too via CV's. I recall you saying in the past that this solution falls short of your high standards, but some of us are OK with it.

Regarding adding an extension to the bottom tab, I've done that a few times. As mentioned, you need to be sure to eliminate the possibility of that extension, or the solder joint, contacting the frame.

[peteski]

But then the lights can (typically) be corrected too via CV's. I recall you saying in the past that this solution falls short of your high standards, but some of us are OK with it.

It is not that it falls short of my standards, it is simply the wrong procedure to use for reversed motor leads.  Direction bit in CV29 is meant to reverse the direction of the entire locomotive (like when some railroads run diesels long-hood-forward).  That's all.

Sure, you can change CV29, then futz around with few more CVs to reverse both headlights,  but is that really a good solution?  Next time your decoder "blows its brains out" (which does happen) and has to be reset to factory defaults, you'll be surprised that suddenly the loco is not running correctly.

Hey, if you consider it to be a good solution, all the power to you.  But I felt compelled to mention that it does not work as most people think about it. Is that ok with you?