Mini Motors Not Running

[Strubbly]

I'm trying to put together a motorised model - a bit of a departure for me...

So I bought a mini-motor from bricklink, and then a couple of 8735 sets from eBay. So I have 3 71427 9V mini motors and 2 battery boxes and connectors and stuff.

It all came today and so I excitedly connected the motors and ... zilch. All 3 motors make a tiny click when I switch on the power but nothing goes round

I guess maybe they're broken - but all 3? Am I doing something wrong? All 6 AA batteries are new - and even if one was a dud I'd still expect the motor to run. Is there a common problem with these motors or am I just unlucky?

Any suggestions on a better way to test? Should I be asking for my money back?

Ben

[allanp]

I'm trying to put together a motorised model - a bit of a departure for me...

So I bought a mini-motor from bricklink, and then a couple of 8735 sets from eBay. So I have 3 71427 9V mini motors and 2 battery boxes and connectors and stuff.

It all came today and so I excitedly connected the motors and ... zilch. All 3 motors make a tiny click when I switch on the power but nothing goes round

I guess maybe they're broken - but all 3? Am I doing something wrong? All 6 AA batteries are new - and even if one was a dud I'd still expect the motor to run. Is there a common problem with these motors or am I just unlucky?

Any suggestions on a better way to test? Should I be asking for my money back?

Ben

Well that small click would indicate there is power to the motors but to be sure, have you checked the wires and battery boxes on another motor that you know works? Have you checked that the electrical connections on the back of the motors are clean and free of corrosion? If so then i'm sorry to inform you that those mini-motors were notoriously unreliable. It is a surprise that none of them work, but not a big surprise. I have three, one went missing, one just stopped working and the other is in a sealed 8480.

[Blakbird]

Any suggestions on a better way to test? Should I be asking for my money back?

I've heard tales of these motors failing on people, but I've never had any trouble with the dozen or so that I've used. It seems unlikely that 3 different sellers would give you non-functioning motors. I'd be more suspicious of the wiring and terminals. They get oxidized over time and don't make a good connection. The micro motor has a lot of internal gear reduction and requires a lot of startup torque, so you need full voltage. I'd check the terminals with a voltage tester or just use a wire brush to clean up the terminals on the wire, the motor, and the battery box. If all that fails, it never hurts to bang it on a table.

[Strubbly]

Wow! Quick responses: thanks!

I don't have any other 9V motors - I've never used them before.

I also don't have a voltmeter but I've tested all the batteries in another device which shows low battery and they all show as full power.

I've cleaned up all the terminals, though they looked pretty clean anyway - no luck.

It's weird the way all three motors make the clicking noise but don't turn. But it doesn't really get me anywhere.

I think I'm going to have to go back to the sellers...

[DLuders]

If you want to see the internal workings of the motor, see http://web.archive.org/web/20050316160255/...repair_html.htm . There is a recommendation to give the motor a shock to get it to rotate freely.

On Philo's webpage http://philohome.com/motors/motorcomp.htm , 3/4 of the way down, it says:

"71427 and 43362 motors are protected from abuses by two devices....Once current limitation is established (for example with a dead short), power dissipation in the driver is very high, and it quickly enters thermal shutdown mode. After that, the output cycles on/off with a period of about 1 second: the driver circuit heats up, stops output, cools down, re-enables output, heats up again and so on."

I'm guessing that something is jammed. Like Blakbird suggested, bang them on a table!

Edited March 13, 2010 by dluders

[Strubbly]

Woo-eeee!!

One of the motors came to life after being dropped 1m onto a tiled floor. I think the "impulse" that worked was up the drive shaft - presumably it jarred the metal plate back into position. But the motor bounced more that once so that might be wrong.

I can't get the other two to work, but at least I can get started on my model...

Thanks for the advice.

[allanp]

Woo-eeee!!

One of the motors came to life after being dropped 1m onto a tiled floor. I think the "impulse" that worked was up the drive shaft - presumably it jarred the metal plate back into position. But the motor bounced more that once so that might be wrong.

I can't get the other two to work, but at least I can get started on my model...

Thanks for the advice.

Sweeeeeeeeeeeeeeet! glad it worked for ya

[CP5670]

One of the motors came to life after being dropped 1m onto a tiled floor. I think the "impulse" that worked was up the drive shaft - presumably it jarred the metal plate back into position. But the motor bounced more that once so that might be wrong.

Nice. I wish that worked for my broken red micromotors. I once tried throwing them across the room a few times and it didn't help.