Full Version: Very poor running Atlas H0 MP15DC
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I have several Atlas MP15DC and they are all smooth and silent runners except the last one I got with a Loksound decoder.
The decoder was humming like crazy. That was surprising because the Loksound decoder's humming becomes so loud only with poor drives. I expected an acceptable level of humming with a high quality Atlas MP15DC drive.

I started to replace the board and the underneath mounted 21 pin Loksound with a Tsunami 2 plug in decoder. That worked fine and the bare drive without lights and speaker did a test drive.
The drive was very noisy. Something made the motor working very hard. There must be somewhere a mayor resistance in the drive.
I removed the trucks and rolled them on the table. They did not roll a tad! It was hard to roll the wheels with a finger.

Disassembling the trucks showed the problem:

Each truck has piece of brass in each side frame acting as a bearing at both ends and as a connector to the wire in the center. The ends of the brass forming the bearings are inwards aligned and press against the wheels on the axis. The ends of the piece of brass need to bend a tad outwards to let the axis with the wheels free spin in the bearings.

That is all. After that the drive runs as good as all other Atlas MP15DC drives and the Loksound humming is barely noticeable and acceptable. About the same level as the GMD-1.

I assume Atlas made an error mounting the trucks in one or more series of younger MP15DC. Don't worry you can fix it in 20 minutes ;-)

ps. Shocking lesson for me: An awfully humming Loksound can be caused by one of my beloved Atlas engines.....