Problem with Mini-9V-Motor

[Heaven]

Hello, I am new here and quite new to Lego Technic. When I was a teen, my cousin gave me some Technic-Sets, but I had to say, I never fell in love with them for their abstract look, comparing to the lovely Legoland-Sets. So I never used the Technics-stuff :(.

Now I am quite older, my children growing fast and I decided to dig out these Technic-Sets from the bottom of my basement. Things were still looking strange (all these connectors and beams and so on) so I tried to find help in the internet and finally found the marvellous technicopedia-Website. This site has such a lot of Technics-history, explanations for beginners like me and lots of reviews, I was so fascinated and I am now complaining a lot, never have given a chance to the technic bricks. But it should never be too late, so my daughter and I started building the 8856 Rescue Helicopter, later the 2nd model of the 8868-set (its a kind of garbage truck; very fascinating for me and the child) and now we wanted to try the Technic 8082 with 2 motors.

We built the Dog (doesnt seem a rabbit nor a cat to me) and there is a red Mini-Motor, that doesnt seem to work. I tried to replace it by an bigger 9V-Motor (the old ones) but this one doesnt seem to work properly, because the pole-reverser changes too fast and the dog barely moves 2 seconds in one direction.

Only for beeing sure: For testing I connected the Mini-Motor directly to the battery-box and it should work, right? Are these Mini-Motors still available or is there a way to repair it or is there another motor available, that has similiar specifications? Or am I doing something wrong?

Thanks a lot for any answer. And sorry for my english, I am from Berlin.

Regards

Matthias

[allanp]

These motors are quite notorious for failing. One thing you must check first is that the electrical contacts on the back of the motor are clean and free of corrosion. Another thing to try is to literally drop the motor onto a hard tiled floor. This can sometimes loosen a jammed internal working which is usually what goes wrong with these things. If this doesn't work you can remove the back carefully to reveal the commutator (a small metal/copper shaft that is slit into segments) and the tiny metal contacts (little fingers) that brush against the commutator will be on the back part you took off. Make sure these contacts do touch, are not too worn and are clean. You may also want to try turning the commutator by hand using minimal force and fingers only. Using tools will likely ruin the motor beyond reasonable repair. After that it gets more tricky to go deeper into the motor. However if you wish to buy a replacement then www.Bricklink.com is probably your best bet.

Hope this helps.

Edited May 14, 2011 by allanp

[DLuders]

@ Heaven: Welcome to Eurobrick! Repairs to the 9V Micromotor was discussed on this Eurobricks topic. If you can CAREFULLY pry the motor apart, you will see the insides (from http://tipionline.netfirms.com/lego/micromotor.html , which can be translated from Spanish to English ):

On this Eurobricks post, Blakbird said "I banged it on the table and it fired right up again! I think perhaps the contacts just get dirty after sitting around for a long time. I guess that just means you need to use them more often." What have you got to lose?

Edited May 14, 2011 by DLuders

[allanp]

Ah, these illustrations really help what I was trying to say

[Heaven]

Thanks a lot for your quick answers. Banging the motor didnt work. So I opened it carefully and had the same insight like on the photos.

@allanp: do I understand it right,that the tiny metal contacts must NOT contact theirselves but only contact the commutator? (in my case, the tiny ones have contact theirselves, but on the spanish site, I understand it so, that this provoces a short circuit, or?) Im quite noob with electrical stuff :).

Thanks for the link to bricklink. Quite expensive these motors are, but if it doesnt work, I will have to buy one. Seems irreplacable for certain things.

Regards,

Matthias

[allanp]

Well they may spring back and touch when taken off the back, but they must not touch each other when they are installed onto the motor, they must touch only the commutator otherwise this will indeed cause a short circuit. The spindle should keep them apart from eachother.

[Heaven]

Well, I tried and tried and all inside the motor seams clean and in good condition but the motor still doesnt work. But I learned a lot and now`ll buy a new one on this bricklink-site.

Thanks a lot for your help!

Matthias

[allanp]

Glad we could help

Just sorry you couldn't get your motor working again

[Alasdair Ryan]

Just a quick thought given how rare these motors are now are people able to sell them for spares or are they finished the minute thay stop turning (off course you could try would david said above ,one would imagine some one like allan or how ever would want to try to make them come to life again,i binned one of those rectangle motors as it was missing the front black axle hole piece.

Now pneumatics it is easy to fix a dud rod with a new one as they are tons of them around compared to micro motors .

Stay tuned Allan if you see this their is something just for you coming soon , i know you will love it.

Edited May 17, 2011 by Alasdair Ryan

[DLuders]

It SURE WOULD BE NICE if TLG produced the long-awaited SMALL Power Functions motor. We have had a "M-motor" and an "XL" motor for 4 years. What are they waiting for?

[allanp]

Just a quick thought given how rare these motors are now are people able to sell them for spares or are they finished the minute thay stop turning (off course you could try would david said above ,one would imagine some one like allan or how ever would want to try to make them come to life again,i binned one of those rectangle motors as it was missing the front black axle hole piece.

There are alot of people on brinklink who buy multiple sets just to break them up and sell the parts as spares. If you can sell all the parts you can get a fairly high return. Also there may be people who have (perish the thought) given up the hobby for one reason or another and so are selling off their collection. So there will probably always be micromotors and rare sets like the 8868 available, for a while at least.

Stay tuned Allan if you see this their is something just for you coming soon , i know you will love it.

SWEEEEEEEEEEEEET!!!!!! I'll deffinately be looking out for that

Edited May 18, 2011 by allanp

[johnnytifosi]

On 5/15/2011 at 4:27 PM, allanp said:

Well they may spring back and touch when taken off the back, but they must not touch each other when they are installed onto the motor, they must touch only the commutator otherwise this will indeed cause a short circuit. The spindle should keep them apart from eachother.

Digging up an old thread but there was some solid info here to keep it alive.

I recently got a used 8082 set but I found out the 9V micromotor didn't work (of course). I dropped it on the floor as some people suggested to no avail. I pushed the 4 tabs with some pins and opened the case, and it looked in good condition in the inside. The gearbox worked fine, the magnet and coils seemed intact. I rubbed clean the rotor shaft and the metal contacts and put the motor back together, but no luck. I tried to place the shaft between the contacts while assembling but I can't be sure about that. How would one do it correctly? I later gave the motor to a colleague who has access to a multi-meter and found out the motor is shorted, but I couldn't know if it is due to my reassembly. Anyway I just forked out 18 bucks for another micromotor from Bricklink and hoping to be lucky this time, but I'm still not giving up on this because of its rarity and seemingly good appearance. Any ideas?

Edited October 28, 2022 by johnnytifosi

[That_LEGO_Guy]

those tiny little fork things in the base need to be spred apart to fit the rotor between them. I had the same issue the firsrt time I put mine back together