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I bought a used MTH Decapod.  This is the 20-3311-2 premier engine that will run on 2 rail or 3 rail.  It has scale wheels and the previous owner used it on 2 rail DC only.  The layout where I ran it has a variac feeding a full wave bridge with a maximum track voltage of 18 volts.  At full voltage it was running about 10 scale miles per hour, and much slower than I have seen in videos of the engine.  It has the wireless drawbar, and I've read those can have issues, but the engine runs and the sound is on, it's just slow.  Anyone come across this before?

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I have no idea, I have not MTH locos.   but I understand they have a lot of electronics built in for the proprietary control system, and for DCC if it has that option.     All that stuff may be using up a lot of voltage to run the electronics.     Or in other words, the electronics are doing something to keep the voltage to the motor down.

A few questions, please:

1.  Do you know what the amp draw on the loco was ?  If it was on a club layout, do you know your loco was the only thing being powered ?

2.  Did you receive the instruction book with the loco ?  It will be of no help in troubleshooting per se, but does tell you where things are [ more or less ];  for example, have you looked inside the gear box to see if the grease has hardened , etc ? 

3.  Do you know if the problem is electrical or mechanical at this time ?  You can remove the loco body and turn the motor by hand, for example.

4.  I would turn the smoke unit and sound off to reduce A draw, etc;  I image those controls are on the bottom of the tender ?

5.  Do you have test stand rollers or the ability to 'block up' the drivers and run it from clip leads ?

6.  Do you have any other MTH locos and are thus familiar with their non-NMRA volt vs speed curves ?

Good luck.  With MTH on DC you'll need it.

Best regards,

SZ [ who is a DC 2 rail person with some MTH locos, but none steam ]

SZ, thank you for your time and here are the answers:

1.  Do you know what the amp draw on the loco was ?  If it was on a club layout, do you know your loco was the only thing being powered ?

It was the only engine being powered, smoke was off, current draw was 250 milliamps with no train, only slightly higher pulling 6 plastic cars.

2.  Did you receive the instruction book with the loco ?  It will be of no help in troubleshooting per se, but does tell you where things are [ more or less ];  for example, have you looked inside the gear box to see if the grease has hardened , etc ? 

I did not receive it but I downloaded a copy.  I haven't looked inside the gear box yet.

3.  Do you know if the problem is electrical or mechanical at this time ?  You can remove the loco body and turn the motor by hand, for example.

I don't.  it runs smoothly, just slowly.

4.  I would turn the smoke unit and sound off to reduce A draw, etc;  I image those controls are on the bottom of the tender ?

Good idea, I had turned those off before I started.

5.  Do you have test stand rollers or the ability to 'block up' the drivers and run it from clip leads ?

I do and that will be the next step.  The sound works, but it isn't that great.  I will likely remove most of the electronics.

6.  Do you have any other MTH locos and are thus familiar with their non-NMRA volt vs speed curves ?

I have 3 of their diesel engines no other steam engines.  I had some of their 3 rail engines previously.

Good luck.  With MTH on DC you'll need it.

Thanks, sounds like I'll need it.

Best regards,

SZ [ who is a DC 2 rail person with some MTH locos, but none steam ]

Hi,

I have some 2 rail MTH engines that I've run on DC using a power pack. They are proto 2 version so I'm not sure if it applies here. I have an MRC 10 amp power pack.

To get the engines started I would turn the throttle up almost as high as the handle would go very quickly and then turn it back down very quickly but not off. The engine would start out slow after that and then it could be controlled with the handle as any normal DC unit would operate from the point. There definitely was a stange bit to the first throttle up part that communicated something to the engines but I don't know what that was and it has been a while now since I've operated with DC.

Also, check to make sure the switches on the bottom of the tender or wherever are set to DC and 2 rail.

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