Shoddy operation from Atlas Master loco from Ebay


Hello all,

I recently purchased an Atlas Master locomotive (U23B) on Ebay, which was described as being in very good condition, however it was bought at an estate sale, and the seller did not know the original owner. After receiving it today, I've noticed it is jumpy when running on a standard DC powerpack. When keeping it at the same power or speed setting, it speeds up and slows down repeatedly, in rhythmic patterns. The headlight flashes on momentarily (maybe about for a half of a second) when power is applied at first. Does this sound like something that could be rectified, or does this sound like a dud locomotive? I just cleaned the wheels thoroughly, so that's not an issue.
Can you check the current it draws when running to see if the draw goes up when the loco slows down?
It sounds like there is some tight spot in the drive train.

Very long time since I had anything to do with models, however Googled it, if I got the right one it has Five-pole skewed armature motor with dual-flywheels, have a look at the flywheels could be one is loose or possibly the gears could just need oiling especially if not used for a long time.
I'd check that there is a good connection between the pick-ups and the wheels. These could very well be worn so there's a good contact at various times in the rotation. This would explain the pulsing and the flickering headlight. This by any means does not mean this loco is a dud, it means it needs a good clean up and some neglected maintenance.

To check for current draw, you need to get a DVM - a digital voltage meter. These are a combination current, resistance, and voltage meters and are pretty cheap these days. You can get one for about $30 at Harbor Freight or even online from various places.

To test current you need to put the meter in series between your power pack and the track all on the power side on the return. The meter then will measure the load drawn by the locomotive.

It's been awhile for me too with real models, and a lot longer since I tested anything with a DVM. :)

When taking the shell off the frame, I discovered it has a DCC decoder installed, a Digitrax DZ125. From what I can tell, everything else is fine under the hood. Wonder if this may be an installation/configuration issue with this decoder... Not having DCC, I don't have a way to test it immediately.
I'm not an expert on model railroading, but you can get a digital volt meter even cheaper than $30. Pay attention has to whether it can handle enough current (amperage). Some DVMs, even some of the more expensive older models, aren't good for more than a fraction of an amp, and many have a separate connection plug for sampling higher amperages, if they can.
I'm not sure how to un-wire the decoder and set it back to DC operation. I have no DCC experience and have never done anything with a decoder. I do know this locomotive has an 8-pin plug and is advertised as "DCC ready," so I would assume the answer would be yes. I just need to figure out how to do that, and can't find much info.

I looked up Atlas Master U23B on Google, and found the loco. Under support, I found DCC operation manuals. I couldn't find one for the U23B in particular, but all of the manuals seemed to be similar, and all of them seemed to indicate that you could operate either on DC direct, or DCC. They did have specific directions for each mode of operation. It might be worth a try.

Think I may have figured this out... The loco no longer has the dummy plug over the 8-pin socket that it came equipped with... I'm assuming it was removed and discarded by the original owner. So now I suppose I need to find one of these plugs out there somewhere. Thanks everyone for the replies!
If the buyer has listed it as "good runner" without actually testing, then you might have grounds to return the item or raise a claim with Ebay. When I cleared out all my old OO stuff a few years back, I made it very clear the kit was being sold as non-runners with the caveat that it might run, rather than the other way round.
the decoder is most likely fine if it is running. Chances are you are having contact issues. you can replace decoders by what are called jumpers from most manufacturers, if it is the decoder. However I would first check the wheels. some lighter fluid and tissue paper works wonders. Use a paper towel. Lay the towel across the tracks. use the lighter fluid on the paper towel getting it really good and moist. Now place one truck at a time on the paper towel and the other on the truck on the tracks. make sure both trucks are set on the tracks as you normally do. Hold the engine in place while giving it power. the rear truck wheels will spin on the paper towel while the front picks up the juice it needs. moving the unit back and forth slightly as well.Do this for about 2 minutes or until the wheels are clean. Turn the unit around and repeat. Lighter fluid is a excellent cleaner. I would also check the pick up leaf springs on the trucks as well. these are copper metal strips behind the wheels on the flange side. you can use a couple drops on a paper towel. using a tooth pick you should be able to clean those as well as the wheel itself.
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If you have access to DCC maybe at a local hobby shop, you can send CV8 a value of 8 to reset the decoder to factory standards.