Author Topic: N-Scale Atlas GP-7 Issues  (Read 1294 times)

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kelleywpns

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N-Scale Atlas GP-7 Issues
« on: March 12, 2013, 10:46:07 PM »
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I thought maybe you guys could give me some advice on this one.  I built a small xmas themed 5' x 3' N-scale layout for my parents.  It has a "double-main" oval with two crossovers and 3x spurs off the inside loop that switch to small industries in the center of the town modeled.   There are two diesels for the layout:  an Intermountain F-7 and an Atlas GP-7.  I installed a Digitrax decoder in the F-7 and a Lenz decoder in the GP-7.

The F-7 can run all day anywhere on the layout ... and at very slow speeds.  However, the GP-7 continually stalls.  It happens even after a thorough track cleaning with a bright boy and/or wiped down with alcohol.  After a track or wheel cleaning, it may be good for a lap around the layout, then it begins stalling again.  I had the same results with another Atlas GP-7 with a TCS decoder.  Both GP-7s are fairly new (new in box, they are ~1995 models) with little to no running time and ran perfectly fine on a DC test track before DCC install.

Again, the F-7 will sail right through the spots where the GP-7 gets hung up without even a stutter.

Any ideas/suggestions would surely help.  Thanks

Mike
Modeling the New Haven and Boston & Maine

skytop35

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Re: N-Scale Atlas GP-7 Issues
« Reply #1 on: March 12, 2013, 10:53:21 PM »
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Try cleaning the wheels of the Geep.
Bill Denton

Skytopmodels.com

kelleywpns

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Re: N-Scale Atlas GP-7 Issues
« Reply #2 on: March 12, 2013, 11:23:33 PM »
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Just to clarify (it's buried in the middle of my original post) I clean the wheels as well ... alcohol soaked rag on the tracks and run one truck at a time on the rag.  Same as cleaning the track, it lasts maybe a lap around the layout.
Modeling the New Haven and Boston & Maine

nkalanaga

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Re: N-Scale Atlas GP-7 Issues
« Reply #3 on: March 13, 2013, 01:37:03 AM »
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My Atlas Geeps also seem to collect dirt.  No matter how often I clean the wheels, or the track, the wheels get dirty again within lees than 100 feet of running.  My Kato electric never seems to get dirty, and hasn't had the wheels cleaned in over a year.  Admittedly it doesn't run as much, but over that time it has run much further, and the wheels are still clean.

It seems to be something about the Atlas wheels, not just the cleanliness of the track.  I even drag an Aztec track cleaning car behind the Geeps on every run, so the track is nice and clean...
N Kalanaga
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PAL_Houston

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Re: N-Scale Atlas GP-7 Issues
« Reply #4 on: March 13, 2013, 11:12:45 AM »
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...the other possibility is that the contacts from the trucks to the frame are either dirty or oxidized.  And, I suppose it is also possible that the tension on the brass contactor strips/arms need adjusting, so they maintain contact with the trucks while traversing uneven spots on the track, such as crossovers....

Good luck!
Regards,
Paul

JSL

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Re: N-Scale Atlas GP-7 Issues
« Reply #5 on: March 13, 2013, 12:41:02 PM »
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or bad contact between the motor tabs and the decoder. I have had the same problems that mimick this with a digitrax decoder.

jdcolombo

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Re: N-Scale Atlas GP-7 Issues
« Reply #6 on: March 13, 2013, 04:47:07 PM »
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...the other possibility is that the contacts from the trucks to the frame are either dirty or oxidized.  And, I suppose it is also possible that the tension on the brass contactor strips/arms need adjusting, so they maintain contact with the trucks while traversing uneven spots on the track, such as crossovers....

Good luck!
You should also check to make sure that the brass pickup strips are actually contacting the brass "prong" on the truck - sometimes the strips get twisted in a way that causes them not to sit properly over the truck contact.   And make sure that the truck contact is clean, and sticks up slightly past the plastic sideframe so that it can contact the pickup strip through its entire movement.

If the engine is running well most of the time, then your problem is most likely transfer of electrical power from the wheels through the truck to the pickup strips.  But you should also make sure that the Digitrax decoder (which I assume is a "drop in") is making good contact with the frame at the connection points.   Digitrax drop-ins are notorious for being slightly thin and not contacting the frame well. You can add a light coat of solder to the pickup pads on the decoder to cure this, if it is a problem.

John C.

wm3798

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Re: N-Scale Atlas GP-7 Issues
« Reply #7 on: March 14, 2013, 09:19:49 AM »
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It may be time to pull the trucks apart and clean the contacts where the axle points hit the bronze strips.  There's little cups there that do tend to accumulate carbon from arcing, as well as lint, cat hair, boogers, and whatever else resides in anything short of a "clean room" at Intel.

I use a dribble of rubbing alcohol and the tip of a round toothpick.  When I'm running my equipment hard and putting it up wet, I usually have to do this after about 20 hours of operation.

Remember, it's the wheels that bring the juice from the track to the wheels, but it's the axle points that get it to the engine frame...

Give that a whirl and see how it goes.
Lee
Route of the Alpha Jets

Lee Weldon www.wmrywesternlines.net

u18b

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Re: N-Scale Atlas GP-7 Issues
« Reply #8 on: March 14, 2013, 09:49:33 AM »
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You may have multiple issues.

A thorough cleaning is a must- as described.

But this loco can also benefit from Bearing Block Magic (or Beardenizing, as some lovingly call it).  This process lowers friction dramatically.

http://u18b.com/tutorials/

Ron Bearden
CSX N scale Archivist
http://u18b.com

"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.

Mike C

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Re: N-Scale Atlas GP-7 Issues
« Reply #9 on: March 14, 2013, 06:49:25 PM »
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Had a similar problem. Turns out the brass contact strips inside the trucks wern't making good contact. Took truck apart and SLIGHTLY bent the wheel wipers inward. Worked great after that.....Mike

kelleywpns

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Re: N-Scale Atlas GP-7 Issues
« Reply #10 on: March 17, 2013, 09:25:43 PM »
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Thanks everyone for taking the time to answer the troubleshooting question.  I took your advice and it did help ... however, I also tried the engine out on my son's small Bachman starter set ( I jumped the DCC signal from the small layout to his track).  Everything ran like a champ.

So ... I believe that the track on the layout is the root problem.  I built it about 5 years ago and applied the 'gleam' method to the track I had read about.  It's proven to be less reliable than old-school methods (for me at least).  Lesson learned (hopefully) before I soon start laying track on my new basement layout.

Thanks again for everyone's input.

Mike 
Modeling the New Haven and Boston & Maine