I recently bought a non-functioning Cybermaster unit [part:71797].

Cybermaster Unit

As the motors in there might be perfectly fine, I'd like to use them. I could not find information on these motors (as opposed to most other Lego motors ^^).

What would be the maximum safe-to-apply voltage for them?

Motor photo

1 Answer 1


I don't have this set, so I can't provide a fully authoritative answer, but 9V is likely to be safe for these motors. The hub that drives them is definitely 9V, as it connects with the rest of the 9V system and runs on 6 AA batteries:

enter image description here

TLG typically overspecs their motors somewhat, so you could probably also get away with running the motor using 12 volts, but it might harm the life expectancy a bit. If you can pull out the actual motor, you might be able to find a model number to look up for a more authoritative answer.

I'd recommend starting with a lower voltage (perhaps 3V) and working your way up to make sure that the motors are functioning as expected.

  • I'm not so sure, the input voltage for the motors has to equal the batterys voltage. As the board might aswell downstep it to virtually any value. Thx for answering (+1) but I'll see if someone might know for sure before marking as answered. If noone comes up knowing I probaly go with your proposition and raise the voltage and feel if they get hot ^^
    – kai-dj
    Commented Nov 20, 2020 at 23:46
  • 1
    @kai-dj That's correct. The motor voltage does not have to equal the battery voltage, it's just a guess that these are the same. You should still be able to play around with these pretty safely without much fear of them letting their smoke out. If you start at 3V and work your way up from there you should be able to tell by the sound, current, temperature, and smell if the motor is running too hot. I hope someone here has this part and a more authoritative answer for you.
    – jncraton
    Commented Nov 21, 2020 at 1:24
  • Seems like 9V ist the voltage to go with. 12V seemed ok, too. I might buy a functioning Cybermaster, to check what the board deliveres to the motors on full speed - if I do so, I'll edit or add new answer.
    – kai-dj
    Commented Nov 23, 2020 at 21:40
  • @kai-dj Sounds good. I'm glad that you were able to get this working.
    – jncraton
    Commented Nov 23, 2020 at 22:54
  • @kai-dj It doesn't have to, but it probably does, because otherwise there would have to be voltage-conversion circuitry on the circuit board, and why should LEGO engineers bother with that? (They could avoid having this circuitry by making the battery voltage the same as the motor voltage) Commented Nov 26, 2020 at 14:33

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