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What is inside the M motor in the new Powered Up system? How is it different from the older Power Functions motor?

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Let's take a look. The first step to disassembling the motor is removing the small Philips screw on the bottom:

bottom screw

Now there are a pair of gray tabs in the back white section that we need to release. I found it easiest to cut them down with a knife. Once those are free, the white section slides backwards away from the motor. Try to do this gently, as there are several gears inside that may go flying and be difficult to find.

sliding open

The motor will be left in the back section.

white with motor

It isn't fixed in place, so you can simply slide it free of the housing.

just the motor

We can see that the PCB contains only a few very simple components. I believe that the larger element in the middle is a resettable fuse, and the smaller one on the left is a capacitor across the motor pins to minimize electrical noise. The tiny black element on the right is a 2.2kOhm resistor between pins 5 and 6 that allows the hub to identify this as an M motor.

We also have the gray section of the motor:

gray section

Down in the end, there is a planetary gearbox that slides out:

gearbox

The gearbox simply slides open:

gearbox internals

It contains two sets of planetary gears:

planetary gears

Overall, this is very similar to the PF M motor with the addition of a small PCB and a resistor to facilitate the component detection used by Powered Up. It's worth noting that this is the same motor used in WeDo 2.0.

  • Question: The picture shows the tiny black speck on the right side sitting between pins 3/4. Does the board's circuitry somehow make the connectivity flow between pins 5/6? – Rin Rio-Oki Sep 25 '18 at 13:33
  • @RinRio-Oki Yes. The brighter green lines on the PCB are the conductive traces. You can see that there are two traces coming off the resistor solder pads connecting them to pins 5 and 6. – jncraton Sep 25 '18 at 14:30
  • Nice write-up. @RinRio-Oki the reason they'd do that is the resistor and other surface mount components would be placed by a machine and reflow soldered in an oven first, then someone would solder the wires on by hand. So they've just put the resistor in the middle and joined it with the PCB tracks so it doesn't get in the way of hand-soldering the wires on. – PeterJ Sep 28 '18 at 11:10
  • Yes, a beautiful write-up. 2nd Question: Is there an alternative to the physical cutting of the gray holding tabs? Does it all snap snugly back together? I'm not preaching LEGO Puritanism, but the piece isn't common, like say... a 1x1 plate, where I can walk away from a Pick-a-Brick Wall with a few thousand, and not care if I put a string through them for a necklace. As for Gray Two-tabs, I have to treat it special because of its rarity. So, would maybe an alternate use of a tiny flat head screwdriver or something to help keep me pure? – Rin Rio-Oki Sep 28 '18 at 14:45
  • @RinRio-Oki There may be cleaner methods of getting this open. I wasn't able to force things apart using a screwdriver. I was afraid I would deform one or both sections of the plastic if I used more force, so I decided to just cut down the tabs a bit. The motor still holds together just fine. Remember, this section is also screwed in place from the bottom, so you don't have to worry about it falling off. – jncraton Sep 28 '18 at 15:14

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