# Revolution problem in Thomas



## Treeman (Jan 6, 2008)

Just installed a Revolution in a Thomas.

Found enough room at the rear under coal bunker. Simple install power in motor out. Removed Bachman board on motor.

Easy to link, and ran first try.

But second trip around loop, we got an over heat message. Cooling off, no help. Receiver seems to be shot!!

Power was a 10 AMP MRC, 22VDC rated output.

What could have went wrong here.


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## nkelsey (Jan 4, 2008)

Was the board under the "coal" or under the bunker inside the motor compartment? I have revolution in a thomas that has run 8 hours at a time without problem (battery though). If it was under the coal load I am thinking there is no ventilation for the board, and they do get warm.


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## Greg Elmassian (Jan 3, 2008)

Seems too short a time for it to fail because of heat buildup in the air in the compartment. Sounds like a defective unit. The Thomas does not draw a lot of current, and there have been a number of successful installs. It would probably not be a bad idea to measure the current draw of the motor, but the Revo should shut itself off... killing the receiver should not have happened, especially if you got the overheat, although we have never gotten a technical explanation of ALL the conditions that can send the overheat message. 

Regards, Greg


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## Treeman (Jan 6, 2008)

The board was located under the coal bunker. But with the short run time and low load, heat build up should be low. We also had no cars connected. 

Is high voltage a problem with these.


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## Greg Elmassian (Jan 3, 2008)

I agree, no way that could have built up enough heat. The only thing I could think of would be a defective motor on the Thomas, that would pull some gawd-awful amps... but that would have been obvious right away. I did suggest measuring it just for completeness. 

Yes, they cannot go much over 22 volts, but I have the same transformer as you I believe, the power G, never any overvoltage problems, but it might be worth measuring the output unloaded, to give yourself a worst case supply voltage. 

I would think overvoltage would not send the overheat message, just kill it... (though, again, we don't know all the reasons for that message) 

Did you have the 6 capacitor bank on it? (not that it should make a difference in it dying, it affects control reliability) Just curious. 


Really sounds defective. 

Greg


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## eheading (Jan 5, 2008)

To the best of my knowledge, applying over voltage to the Revolution would not damage the receiver. It would just not work. As soon as the voltage would drop below the specified maximum, it should work again. I regularly apply over 24 volts to my receivers when I install freshly charged batteries, and I have never had a problem. Again, as Greg has said, it surprised me if the current draw exceeded the Revolution limits that it would say "overheat"; but then again I at least do not know all of the conditions that will make this message show up.

Ed


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## Madstang (Jan 4, 2008)

Did you see magic smoke? Did you smell burnt electrical? Maybe a wire shorted out. I always wire in a fuse just in case. 
When you start getting into wiring and small places, or kind of small places, you can sometimes, if not fullly shielding wires, run into a wire posing a problem of touching where it shouldn't. 
Then again if the aformentioned was not an issue then a defective decoder is likely the issue...not sure. 
Use another one, but wire in a fuse..say 5 amp or so. I have limiited electronic skills, so I usually have to approach things maybe concieved as the "long way". OR also known as the process of elimination. 

Again IMHO


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## derlux (Feb 17, 2009)

I´ve had the same problem with a track powered Aristo Mallet from a Buddy. I installed the Revo without the capacitor bank. It was no fun watching the Loco try to run. It was only a stop and go, stop and go..... till we got the overheat message. After installation of the capacitor bank the problem never showed again. 

Marco


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## Madstang (Jan 4, 2008)

The Aristo Mallett I bypassed the poly fuses and never had a problem with it stopping and going. 
I remember the days when locos did not have boards in them and everything had to be hard wired. 
I just converted a set of older Aristo FA-1,A,Bs' that was fun to take me back to a older age.


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## Treeman (Jan 6, 2008)

Did not connect cap. No shorts in wiring. Something did burn, could tell by smell, nothing visual.


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## Madstang (Jan 4, 2008)

Mike maybe a reversed wire? If nothing else maybe a bad board..again try another one....use inline fuse.


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## aceinspp (Jan 2, 2008)

One thing is they do not like the higher voltage. Its possible it got the magic smoke to work. This install should be fairly simple as all you are dealing with in motor leads and track pick ups and nothing else. May want to try another board and use less volts to the unit. Later RJD


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## Treeman (Jan 6, 2008)

I think that I may have found the problem.

The 10 AMP MRC is rated output of 22VDC, however with no load it read 29VDC on my Fluke.

Loaded the voltage dropped to 22VDC. Not sure of the load required to get that drop. But with Thomas stopped the load would be very little.


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## Greg Elmassian (Jan 3, 2008)

hmm... might have cooked it? Lewis Polk himself was very specific on his forum about not going over 24 volts. 

just went out to the garage, my HP equiv of your Fluke measures 27.55-27.56 volts open circuit, and 20.7 volts with a 43k ohm resistor. (same MRC power G) 

That's under a milliampere = 0.000481 amperes. 

I would think that if yours drops to 22 volts with a similar load, then the Revo is very sensitive to overvoltage, if this is indeed what happened. It does not seem that this momentary overvoltage would do it, since any load (at least here) takes the voltage down to an acceptable level. The Revo MUST draw at least 1 ma to run it's microprocessor. 

Hmm... Interesting, but I don't think this is it... but maybe there is a design flaw somewhere... 

Regards, Greg


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## ORD23 (Jan 2, 2010)

I dropped a Revo rx into my Bachmann Forney along with a PB-9. It is a small tight space that some other modellers didn't have any problems with. My Revo rx kept overheating after one loop also. I removed the PB-9 which gave me a little bit more room (placed it in a trailer tool car), and I cut a hole in the tender inside of the cab. I have not had any problems with it since. So, I believe air flow/circulation was a problem on my install. They (rx's), may need extra space to stay cool. BTW, I would like to thank Kevin Strong and Stan Cedarleaf for their help and advice on my Revo & trailing car set up. 

Ed


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## TonyWalsham (Jan 2, 2008)

I was under the impression that the REVOLUTION was claimed to be rated 5 amps continuous with a 9 amp peak. 

There is a big difference in the VA rating if the calculations were made at 12 volts rather than at 24 volts. 

Does anyone know what voltage was actually being used when the current draw was being measured?


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## Treeman (Jan 6, 2008)

Tony, are you looking for the rating from Aristo??


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## Stan Cedarleaf (Jan 2, 2008)

I've used the REVOLUTION with 18.5 volts drawing over 5 amps and running that way for 2 hours. Measured it with a voltmeter and ammeter in a car. 

When running at Marty's last year. I did shut the receiver down with an overload message, pulling a string of 11 USA passenger cars with the FABBA set when one of the passenger car trucks derailed.

Other than that, I pulled them just fine.


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