# GP-40 power problem



## JackM (Jul 29, 2008)

My Aristo GP-40 got substantial use last summer, ending up with worn out plating on the wheels, which were replaced through the kind efforts of Navin at A-C. This year, I had no stalling problems at first, but now it's stalling as much as before. When I took off the bricks today, I remembered reading a section on Greg's website regarding the strips on the little PCB at the top of each block that are supposed to make contact with the strips in the block, but lack anything springy. Rereading that passage today, Greg suggests applying some grease to help the pieces make contact. I added a small dab of NoAlOx (grease is grease, right?) and put it all back together. No change.

Symptoms: mainly at yard speeds, stops for no apparent reason; SV SS track only one year old. I merely push the rear end of the body to either side, or tip the upper portion of the body a bit (a quick poke at the top of the long hood) to get momentary power - barely long enough for the Quantum sound to start - then dead again. These sideways pushes aren't as effective at the front of the engine; a small sideways push at the rear always gets a brief return of power, then nothing. Wiring seems neat and tidy.

Advice would be apprecited. Hopefully, no one's going to tell me to pull the bricks apart.

JackM

If you're familiar with that particular page on Greg's website - yes, those sharp edges were duct taped ages ago.


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## NTCGRR (Jan 2, 2008)

so the power pick up ,,feeding,, the motor is not making contact?? I was thinking the motors are direct feed from boards.??


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## Greg Elmassian (Jan 3, 2008)

Could be a number of things. 

first, check power pickup on every wheel, there is a weakness in the Aristo design that can make one or more wheels "dead". 

The GP40's don't have the little fingers on top of the bricks like the 3 axle blocks do. 

You might have a dead wheel or two. 

Put it on it's back and take 2 wires to your power pack. 

Try every wheel. 

How does the plating look on the wheels? 

Greg


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## Dan Pierce (Jan 2, 2008)

I find the wires break on the side frames, and the heat shrink makes you think these are connected, you must do as Greg said and meter the wheels.


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## jmill24 (Jan 11, 2008)

The center metal frame has square holes where the motor block wires pass thru. These holes can have sharp edges that cut thru wire insulation causing them to short on metal channel [email protected] url(/providers/htmleditorproviders/cehtmleditorprovider/dnngeneral.css);


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## Greg Elmassian (Jan 3, 2008)

He acknowledged that in his first post: 

"If you're familiar with that particular page on Greg's website - yes, those sharp edges were duct taped ages ago." 

You might want to read about the "prime mover basics" on my site... shows how the little finger touches a spring to bring power from the wheels. 

I'd check Dan's suggestion, metering the wheels should do the trick, you could also gently tug on the wires... 

Greg


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## JackM (Jul 29, 2008)

Greg - Thanks for directing me to the prime mover basics section of your websites. That's a lot of material! 

And I can see a lot of help for my current problem there. But I'm going to hold off until I have a long rainy day to delve into it. For now, I'm going to finish DCC-ing my SD45 and put the handrails on, etc. and put it out on the layout. I'll have three out of my four locos running; not such bad odds. 

I'll report back on what I learn on my trip deep into the innards of the GP. 

JackM


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## Greg Elmassian (Jan 3, 2008)

Good deal Jack. On the SD45, under heavy loads, you can exceed the ratings of the "polyfuses", and you might have to bypass one or more of them. Just a tip if you get a situation where it runs and then stops under very heavy load. With 4 motors, you can exceed 3 amps. 

Greg


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## JackM (Jul 29, 2008)

To Greg, (and anyone else who's read his extensive "Prime Mover Basics") - Ya think????











Opposite clips from one of the gearboxes. Note curvature of center section of left clip. Guess I should flatten it out before proceding with delicate finger adjustment. The rest ain't much better. Thanks for making your efforts available to the rest of us.

JackM


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## Greg Elmassian (Jan 3, 2008)

So the cllip on the left definitely will not contact the spring, thus no power pickup. they actually need to be a bit inwards, the one on the right is marginal, needs to be bent a little more to the "right" in this picture. 

The poor design is that the finger tries to touch the spring, and the loops of the spring are far enough apart that this is a tricky proposition. 

You can also assemble the clip, and then carefully push the finger into the spring. 

For those of you not familiar with the Aristo internals, the metal clips above are pictured below:










The "finger" am talking about is in the "hole" at the top of the clip in the above picture. ALL of the current of that wheel goes through that finger... the finger is supposed to touch a spring, and the spring has a ball at the end of it, and that touches the axle, and thus the wheel.










The "finger" is often not bent out enough to touch the spring, or "misses" the spring, and NO POWER PICKUP FROM THAT WHEEL.

Now I've often wondered if that finger should not have been 90 degrees to the rest of the metal clip, and the base of the spring sits on it. I need to research to see if the spring is still held in place properly, or the "angled finger" does this.


This revelation and my subsequent refusal to retract my statements led me to be banned from the Aristo forum. 

The funny thing is that when I shared this with Aristo, it was denied, and I agreed to retract my statements from my web site (yes, Lewis Polk wanted me to edit my web site), provided I could show them first hand.

I told them to bring a motor block to the Big Train Show... they did, and I showed them that ONE HALF of the 8 pickup points were DEAD, and this was on a motor block of their own choosing!

The thing that fools people is that the siderods will conduct electricity somewhat, so a "dead wheel" is not detectable by just a test light, since the dead wheel may conduct via a siderod to a "good" wheel.

The way I first really discovered this was smoke coming from a siderod on a loco! A lot of current was going from a "dead" wheel, through the siderod, to a "good" wheel, and the poor contact between the siderod and the siderod pin, combined with a lot of current and oil made smoke!


Note that the ball bearings on each axle do NOT conduct, they are hybrid, they have ceramic balls, i.e. non-conductive.

Anyway, an interesting discovery, and finally solved many mysteries, like why my mallet, which supposedly hasd 16 pickups on the drive wheels, ran BETTER when I added more pickups to the tender!

OK, so maybe more than anyone wanted to know, but there are often "hidden" reasons your loco might not be running right.

Greg


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## JackM (Jul 29, 2008)

And here's the rrrrest of the story, he said, venting more than anyone cares to read.

Yesterday started out getting soaked while walking the dog - it wasn't raining when we started out. So I spent the entire day fighting these stupid clips. My conclusion is: if the clip don't fit, you cannot commit....to getting a true fix. Forgive my lack or artistic talent:









Drawing on the left is what you get (on a GP-40 that's giving you electrical problems). Green is the gearbox, grey is the metal clip that is supposed to snap onto the gearbox. Notice that the red line - the interior dimension of the metal clip - is shorter than the black line, the exterior of the place the metal clip is supposed to snap onto.

Drawing on the right is what you end up with. Trying to snap the clip onto the gearbox causes the clip to spread outward, forcing the horizontal dimensions to become diagonal. The top end, holding the legandary "finger", leans away from the gearbox right where it's supposed to make contact with the spring. In the words of the old Perry Como hit: "It's Impossible".

In my case - getting the wheels replaced on both blocks because of worn down metal plating - one block has clips that are correctly sized. They are the only wheels getting electiricity from the track. The other block has four of the most hopeless clips imaginable. As Greg mentions in his motive power page, this metal won't take much bending. It breaks in no time. Trust me.

My GP now has one good brick (as mentioned) and the same useless brick. Except the clips have been tweaked as much as I could. One clip is now without finger. What I tried for that one, was to strip some 24 guage stranded wire and wind it around the top of the clip, hoping to get contact with the spring. Maybe it worked, but one good contact out ot four won't do any good anyway. At this point I'm not inclined to take it all apart and try wrapping wire around the other three. If someone tries that, please let us know how you do.

I think I'll just order some replacement parts from A-C. And those clips had better fit right.

Again, Greg, thanks for all your information. But some things just can't be fixed.

JackM


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## Paul Burch (Jan 2, 2008)

I don't think I saw anything in this post about motors. Does this unit have the "new" motors or the the first run motors that can draw excessive current? That could also lead to quicker plating loss.


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## Greg Elmassian (Jan 3, 2008)

Main problem is stalling, intermittent operation... that's not typical of the motor failure problem: excessive current and smoke... 

Looking at the power transmission path, it's the typical failure, no pickup from the metal clip, so no current pickup from that wheel... 

But he could have excessive current draw too... hoo boy... 

Greg


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