Mini Motor not spinning

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G’day, I have a question that someone may be able to help me with. Apologies in advance for the long explanation.

The reason for my purchase through Core Electronics was to replace a Mini Motor on a Michael Jordan Telephone. The phone has a dome in the shape of a basketball that opens when the Phone Rings. This motor pulls back the 2 parts of the Dome exposing a Stadium underneath. There is sound, lights and another Mini motor also makes the crowd do a Mexican Wave. There is a link below so you can understand what I am talking about.

The original motor was working but it didn’t seem have the strength to operate the cogs to open the Dome and when I placed my finger on the shaft it would stop very easily. The Mini Motor operating the crowd seem to be stronger.

The phone operates with 4 x C 1.5 Batteries running all the features.

The motor I am replacing has no markings on it at all. I purchased a couple other motors prior on ebay
• DC 3-6V Mini Miniature DC Motor
• 3V 1.8W 14500RPM High Speed Mini Micro DC-Motor

Both were the same size and fitted the slot. Both motors did not spin although when I spun the shaft it felt like it was trying to spin.

I thought Core’s Motor being a different voltage 4.5 to 9VDC instead of 1.5-4.5V may work. Core’s motor fitted fine but when I started it the music played, then when the Dome was to start opening (motor spinning) everything just stopped and the rest of the sequence didn’t happen, when using the 2 other motors they didn’t spin but the entire sequence worked.

Not sure what’s happening. I assume it’s a voltage problem, I do have an old multi meter maybe I will see if a can get the voltage reading.

Here’s a Link to a Jordan Phone to see what I’m talking about

Any suggestions would be appreciated.

Thanks

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Hi Stephen, Welcome to the forum :slight_smile:

I can confidently say I don’t think I’ve ever seen a phone as unique as that and I doubt I ever will see another like it.

This would be incredibly helpful, at least so we know what the motor controller is sending to the motors, until we know that the motors are receiving the right signal to drive them we can’t tell if the fault is isolated to the motors themselves, even though they may seem the most likely component to have worn out.

The first step in troubleshooting is always to confirm that your power supply is operated as you expect it to.

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Hi All.
To quickly check a small brushed motor disconnect it and short out the connections. Try to spin it with fingers. It should be much harder to spin by hand than with the connections open circuit. Should be easy open circuit and quite a bit harder when shorted. Depends on the condition of the brushes. In some cases with a good motor you won’t be able to turn with fingers.
Cheers Bob

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Hi Bob,

That’s a cool trick I haven’t heard before, I’ll have to mentally file that one away because I am certain to need it sooner or later.

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Hi Trent
Old head, old trick. Learned while installing and commissioning 10kW and 40kW HF transmitters a lot of years ago. These units were tuned automatically and as a result of that had several very nice brushed motors and gearboxes. These units back in the 80s cost about $400 each and another $400 for the gearbox. If having a problem with the auto tuning this method was a means of quickly checking the motor as a first line of trouble shooting. Handy to remember.
Cheers Bob

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Thanks for the reply Trent.

I will check tonight and let you know.

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