# Drone propellor not spinning. motor fine. no voltage

#### george2525

Jan 30, 2015
170
Hello.

My sons drone proppellor stopped working so I tested the motor and its working. the circuitboard (some generic microcontroller I assume) does not supply the approximate 3.2V to the said propellor when we try to fly it. all others work fine.

I know this may be a microcontroller issue or perhaps some tiny connection break in the board but perhaps one of you can suggest something I havn't thought of that may be possible to look at. probably a lost cause but worth an ask.

the drone is cheap and will not be covered by manufacturer sites / forums (unlikely)

I cant access the programming elements as there is no port on the board.

any help would be great, thanks

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,507
Please post some photos, of the whole drive, and closeups of the motor, and connections to it.

Jan 30, 2015
170

#### george2525

Jan 30, 2015
170
I have circled the motor connection in red. the motor works (tested with alternate supply)

Mar 5, 2017
1,180
Last edited:

#### george2525

Jan 30, 2015
170
Vds seems to be locked at 3.7V whether the motor is supposed to be on or off. voltage lowers on all other same transistors.

#### Alec_t

Jul 7, 2015
3,287
Sounds like that transistor is dead, then.

#### Tha fios agaibh

Aug 11, 2014
2,242
Looks like moisture got in along edges of board. I agree transistor is highly suspect, just don't know for sure if that's the one.
I'd flip it over to inspect components on the other side and to better understand the motor ckt path.

#### george2525

Jan 30, 2015
170
ok thanks anyway. I get a headache when I try to look at circuits so small. im not even sure if i can replace the transistor if i wanted to but i might try. yea the moisture theory is probably right.

#### Bluejets

Oct 5, 2014
6,083
Next time it might be a good move to get a "waterproof" drone.
Saw at Banggod the other day, a quad that is almost indestructable.
Dump it completely under water, no problem, jump on it, no problem, cut off one side of each prop , no problem, unit still flies.
Unbelievable and all up cost of around $45, complete with tx..... battery and charger. See if I can find a link. https://www.banggood.com/JJRC-H31-W...ds=mywishlist&ID=42482521800&cur_warehouse=CN HV powerlines could be a different story though .... Last edited: #### george2525 Jan 30, 2015 170 thanks, looks good but some amazon reviews say it breaks easily and that the advert is lying (no surprise). think ill wait until the prices on good ones come down #### dave9 Mar 5, 2017 1,180 ok thanks anyway. I get a headache when I try to look at circuits so small. im not even sure if i can replace the transistor if i wanted to but i might try. yea the moisture theory is probably right. If you don't have a hot air station to desolder it, you might try using a dremel (rotary) tool with a cutoff wheel to gently sever the body of the transistor then you can desolder one leg at a time. That doesn't look like it would be hard to solder a new transistor in if you have a small iron tip in good condition and something to hold the board still. Once it is confirmed working, spray conformal coating over the whole board to waterproof it. Water is a huge problem with the *junk* coming from China where they don't even bother to adequately clean off the water soluble flux residue, so far too easily water is going to cause corrosion and electrical paths. If the board didn't have the wires all the way around it and what looks like silicone caulking holding them down, I might try cleaning the whole board off with a toothbrush and detergent solution first but as it is, looks like a fiddly cleaning operation around delicate wires. Maybe a small paint brush is more appropriate than a toothbrush for that. #### Bluejets Oct 5, 2014 6,083 thanks, looks good but some amazon reviews say it breaks easily and that the advert is lying (no surprise). think ill wait until the prices on good ones come down Wouldn't hold my breath. Have you see "expensive" ones that are waterproof?? Have a link perhaps?? #### dave9 Mar 5, 2017 1,180 Next time it might be a good move to get a "waterproof" drone. Saw at Banggod the other day, a quad that is almost indestructable. Dump it completely under water, no problem, jump on it, no problem, cut off one side of each prop , no problem, unit still flies. Unbelievable and all up cost of around$45, complete with tx..... battery and charger.
See if I can find a link.

https://www.banggood.com/JJRC-H31-W...ds=mywishlist&ID=42482521800&cur_warehouse=CN

That one is now cheaper ($25) on Amazon: https://www.amazon.com/Goolsky-Waterproof-Headless-Rolling-Quadcopter/dp/B01JROH8JA?tag=dronerush-20 Most waterproof drones are in a much, much higher price class, but there is this$80 Goolsky Q353:
https://www.amazon.com/dp/B06XT2Y732/ref=dp_prsubs_1

#### Alec_t

Jul 7, 2015
3,287
That one is now cheaper (\$25) on Amazon:
The spec according to a different ad for that drone says the airframe is waterproof. Who knows about the rest of it?

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