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Converting Athearn Blue Box Locos to DCC with Sound
Travis asks readers:
“I’ve got 4 old Athearn Blue Box locos (DC) and I want to upgrade them to DCC with sound. A hobby shop said it’s doable but might not perform great. Has anyone done this successfully? What should I expect, and how can I get the best results?”
2 Responses to Converting Athearn Blue Box Locos to DCC with Sound
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While I’m not psychic, what the hobby shop was referring to is that many (most?) older locos have motors that draw a lot of power. This may result in DCC decoders being unable to supply enough power to the motor for the loco to perform well. You might want to measure the power draw on DC , or check the owner’s manual if you still have it, and verify if the decoder can handle it. It might be better if you actually replace the motor with newer ones that require less power.
The problem with the older locos is that they have very small 3 pole motors. The result being that their torque is very low. With any of the new digital systems, they have a hard time getting the loco to start moving. These systems have feedback so that the controller understands the motor characteristics to feed the appropriate voltage/current to the motor when under its control. They do not feed DC as we know it, but a pulsed waveform. In a pulse, there is always a point where the voltage goes to a zero invariably. DC does not have this issue. Once it is above zero, it is always above zero, so to speak.
I have tried a few of such motors with no luck with a different digital system and gave up because they simply don’t move at the lower settings and fails the programming altogether. I don’t know about DCC but I assume they all have the basics similar.
If you have 5 pole motors that are rare in older locos, it will work as they have much better torque. This is because, unlike a 3 pole armature, a five pole armature needs to turn much less for the next pole piece to become energized. 120deg. vs. 72 deg.