# RDC-3 Surges



## mocrownsteam (Jan 7, 2008)

Just went downstairs to run my new RDC-3. It's running off of track power with the lights on and the smoke unit off. At low to medium speeds it moves then slows, moves then slows. If I run at Bat-out-of ****- speed it seems to be smoother. My two other RDC-1's run fine at all speeds so it's not the power supply. Bad electronics? Getting ready to install Revo board, but don't want to do anything before this issue gets repaired. Any ideas before it goes to Aristo for repair?

Mocrownsteam
Hudson, Massachusetts


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## chuck n (Jan 2, 2008)

Clean your track and check you rail joiners.

Chuck


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## Madman (Jan 5, 2008)

And if the track cleanliness, and joints are not the answer, send it back to Aristocrap.


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## Greg Elmassian (Jan 3, 2008)

can you get it to do the same thing on rollers? 

My guess is an electrical pickup problem, wiring bad either in one truck, or wiring somewhere else. 

If you can get it to do it on rollers, then you will probably see it's one truck acting up. 

You can also ship it back of course. 

Greg


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## eheading (Jan 5, 2008)

Sounds an awful lot like the problem I'm having with my LGB Mogul, and that is a bad drivetrain.

Ed


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## toddalin (Jan 4, 2008)

Also clean the engine's wheels with Q-tips and 91% Isopropal alcohol, smoke fluid, or whatever works best for you.


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## Greg Elmassian (Jan 3, 2008)

If the plating is worn, like mine, it will take a wire brush to remove the rust, the loco has steel wheels. Kadee wheel cleaner works well. 

Doubt that is the surging problem, though. See if it will do it on rollers my best advice to isolate the problem. Both trucks surge will take you down a different path than one surging. 

Regards, Greg


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## toddalin (Jan 4, 2008)

Posted By Greg Elmassian on 15 Oct 2010 07:53 PM 
If the plating is worn, like mine, it will take a wire brush to remove the rust, the loco has steel wheels. Kadee wheel cleaner works well. 

Doubt that is the surging problem, though. See if it will do it on rollers my best advice to isolate the problem. Both trucks surge will take you down a different path than one surging. 

Regards, Greg Surging on the track may bear little sembalance to surging on rollers.

Say the track has dirty areas, as they tend to do because of proximity to a tree branch releasing sap, a snail crossing, etc., or _because it is a low spot that your track cleaner just misses as they can do_. Also say that the rear set of trucks/wheels is cleaner than the fronts.

As the train goes down clean track, the dirty front wheels pick up intermittanly and the clean wheels continue to pick up just fine, so the train runs smooth because the clean wheels are getting you through.


Now the front dirty wheels come to a dirty spot of track. No big deal because these wheels weren't doing much to gather power and the clean wheels are still on clean track and the train continues.

Now say the clean wheel hit the dirty section of track and the dirty wheels are on clean track. The train hesitates/bucks/stalls/etc. until the clean wheels can make their way to clean track because even though the dirty wheels are on clean track, little power gets through the dirty wheels.

Now put it on rollers with a set of dirty and a set of clean trucks. Power is continuous through the clean trucks and the train runs smooth regardless of the condition of the other trucks.


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## toddalin (Jan 4, 2008)

...


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## Greg Elmassian (Jan 3, 2008)

Agreed with all your analysis... putting rollers was simple, easy to do test I suggested. 

I'm guessing and having fun to see if my guess is right, since all we can do is speculate until we get more info. 

Was not meant to bash your analytic powers Todd, which are definitely in force, no question. 

My speculation are based on the problems I have had with my RS-3 and have eaten 2 motor blocks so far, plus endured a number of wiring vagaries, plus what I consider a weak power pickup design in the motor blocks. 


Regards, Greg


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## chuck n (Jan 2, 2008)

The rollers are a good idea, but to prevent the problem of the "good" block from powering the bad block, insulate one set of rollers with a piece of cardboard or paper on the track. Test it with only one roller powered and then the other one.

Chuck N


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## mocrownsteam (Jan 7, 2008)

*Update on testing*. Thanks for the good ideas. I decided to feed power through the battery connector to eliminate possible truck pick-up problems. Lights and smoke were switched off and I still get the surging effect. One local took a guess that the electonics are wired wrong. Something about the polycaps? Maybe it does need to go back to Aristo.
mocrownsteam
Hudson, Massachusetts


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## Greg Elmassian (Jan 3, 2008)

Now put it on rollers and see if it's just one truck or both... 

I'll bet it's one truck... "polycaps" is probably a reference to the polyswitches, they are thermal cutouts for overload... and they do NOT react fast, extremely unlikely they could vary fast enough to surge. 

I'm betting on an intermittent power problem (to the motor), or possibly a gear train problem. I think it's the former... that's my bet. 

Greg


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## mocrownsteam (Jan 7, 2008)

UPDATED TEST RESULTS. At Greg's suggestion I put the unit up on rollers and discovered that both trucks are doing the "surge". It's got to be an electronics issue so it's off to UPS to send it to Navin. I'll let him figure it out. Doesn't say much for the factory testing program in my mind. 
Mocrownsteam 
Hudson, Massachusetts


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## George Schreyer (Jan 16, 2009)

When you feed power, flip it over and watch the wheels. If the trucks start at different voltage or run at different speeds, the slow one is bad. 

When one truck runs at a different speed as the other, they "buck" each other. The happens on locos with mismatched speed as well, but with two locos the problem is easy to see. With the RDC on it's back and no extra mechanical load on either truck, the problem will also be obvious. 

The older style Aristo bricks were susceptible to this problem, I have only on loco with newer bricks so I haven seen enough to tell of this kind of problem has been carried over to the newer bricks.


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## Del Tapparo (Jan 4, 2008)

Posted By mocrownsteam on 16 Oct 2010 11:29 AM 
... Doesn't say much for the factory testing program in my mind. 


Surely you jest! You think they (not just Aristo, but any of them) actually test this stuff?


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## Greg Elmassian (Jan 3, 2008)

Hey Del! Now have a heart. You know the extensive testing routine: put it on the rails, if it moves at all under DC (no matter what direction) it's good to go! hahahaha! 

On the RDC, very interesting about both surging on rollers, hard to imagine what would do this except the internal voltage regulator going nuts and pulling too much voltage. 

I have seen this voltage regulator go nuts and melt down... most of them were a small microprocessor, which could reset and go cuckoo... 

I can also think of something else, like something trying to short every so often. 

I concur, back to Aristo... I would definitely not try anything further. 

Regards, Greg


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## aceinspp (Jan 2, 2008)

Turn it on its back and apply power to each wheels set. You may find that one set of wheels may not be picking up. return to AC for a new brick. Later RJD


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## mocrownsteam (Jan 7, 2008)

Folks, 
Thanks for all the good suggestions. Testing revealed that it was not a power pickup problem as it performed in the same way when fed power thru the battery jumper. It has to be something in the electronics. It is now at Aristo to see if Navin can figure it all out. 

Mike McCormack 
Hudson, Massachusetts


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