Boost motor teardown and repair

[brickvan]

I have some boost external motor from a friend. Connected to the hub, they're completely dead.

Opening and checking results in a suspect, a short circuit in the motor or at least some current overdrawn as the PTC is triggered (it is a 0.2mA resettable fuse):

If I sodler another small motor, it works perfectly. So definitely a wear problem in the motor.
However it is difficult to find a replacement. It is a double axle (and you can find some on Ali) but my biggest problem is how to replace the gear properly (at home, no garage lab)

Do you have any idea on how to find a replacement gear & motor?

Thank you in advance!

[Toastie]

7 minutes ago, brickvan said:

some boost external motor

Nice work so far!!!

What exactly is a boost external motor (LEGO #)? Is it 88008, the medium linear motor?

Best
Thorsten

[2GodBDGlory]

Hmm, I don't know about sourcing a motor, but it might be possible to move the gear to a new motor. I'd start by heating up the gear with a lighter or heat gun, and then see if I could pry it off with a small screwdriver. I've seen 3D-printed tools that use a screw to press a gear off a larger stepper motor, but I doubt that would fit here

[msk6003]

If you are certain that the motor itself is broken, the surest way is to break it open and remove the gear. You should consider the standard method of separating the pinion gear nearly impossible because the gap between the Lego motors and the pinion gear is very small.

[brickvan]

Thank you! Multiple answers here:

• @Toastieyes it is the https://www.lego.com/it-it/product/medium-linear-motor-88008
• @msk6003 yes, sodlered another one and it works. Same concern, no easy to disassemble. I'm thinking about finding a similar motor and then gear (1.98mm shaft, 4.30mm diameter, 2.25 height and 10 teeths) and create a new assembly however the gear has to bee truly identical as there is no room inside the motor for error

 

Edited May 28 by brickvan