DC Motor won't reverse

[Bl1ndman]

Hi
I replaced my treadmill DC incline motor as it would not decline, after troubleshooting the switch and other components.

The replacement works fine.

So where do I start to troubleshoot this motor as I had it apart at the weekend and everything looks good, it just won't reverse direction!

Any ideas?

 

[Mursal]

To reverse the direction of a DC brush motor with permanent field magnets, just reverse the polarity (swap the two feed wires around).
If you have wired field magnets you leave them as they are and reverse the polarity of the brushes.

Usually an issue with the switch gear rather than the motor, if you loose only one direction

Hope this helps

 

[Bl1ndman]

Thanks for the reply.

With the good motor in-situ the switch on the console reverses the polarity.

With the old motor off I can physically extend or retract the threaded spindle so I would assume the mechanical side of things is fine?

 

[jj4091]

Thanks for the reply.

With the good motor in-situ the switch on the console reverses the polarity.

With the old motor off I can physically extend or retract the threaded spindle so I would assume the mechanical side of things is fine?

If you are saying that the motor turns in the reverse direction when removed from the machine , then it can only be a mechanical problem. Either something slipping or binding in one direction & not the other. Are you testing the polarity at the controller or the connections to the motor?

 

[Bl1ndman]

If you are saying that the motor turns in the reverse direction when removed from the machine

No I'm not-sorry for the confusion. The thread that drives the treadmill can be mechanically wound up and down.


Here's a link to the motor from
Ebay

The other pictures show the circuit diagram if that helps

 

[Spark123]

The motor on ebay is not DC?? Is says 220VAC

220v between COM and Red = counter clock wise
220v between COM and Black = clockwise

 

[jj4091]

The auction has ended on the item you linked to. Do you mean this one http://www.ebay.co.uk/itm/Reebok-Ro...1648785954262848565&pid=100011&prg=1005&rk=3& or one that is similar as this one does indeed say that it requires a DC input. Also what are you using to check polarity & measure volts?

 

[conny]

The motor on ebay is not DC?? Is says 220VAC

220v between COM and Red = counter clock wise
220v between COM and Black = clockwise

You will often find that although the input is 230VAC it is transformed down and rectified to about 24 or even 12 VDC

Not many people have a DC supply at home.

 

[Monkeh]

The motor on ebay is not DC?? Is says 220VAC

220v between COM and Red = counter clock wise
220v between COM and Black = clockwise

You will often find that although the input is 230VAC it is transformed down and rectified to about 24 or even 12 VDC

Not many people have a DC supply at home.

That's definitely an AC motor. Note that it has a run cap and frequency specified.

 

[conny]

Sorry Monkeh, didn't have time/bother to look at the link. Just going by a few I've had brought in for repair. Some are AC but there have been a couple with circuit boards containing rectifiers/transformers etc that cause them to run on 24VDC

 

[ericmark]

Most AC motors have two windings a start winding and a run winding. What I think you have is a motor where both start and run are the same resistance so when powered from one wire the other becomes the start winding.

I would guess one winding burnt out hence only working in one direction. With some motors if you don't power the start winding flicking the motor in either direction will cause it to run in that direction.

In fact some small motors it is a little hit and miss which direction they run in. My ice cream maker is like that. Switch it off and back on and direction will reverse.

 

[ban-all-sheds]

If it goes backwards do you get custard instead?

 

[Bl1ndman]

Most AC motors have two windings a start winding and a run winding. What I think you have is a motor where both start and run are the same resistance so when powered from one wire the other becomes the start winding.

I would guess one winding burnt out hence only working in one direction. With some motors if you don't power the start winding flicking the motor in either direction will cause it to run in that direction.

In fact some small motors it is a little hit and miss which direction they run in. My ice cream maker is like that. Switch it off and back on and direction will reverse.

Thanks for this explanation-I think this is the answer.

Pity I can't tell DC from AC ! (despite the obvious symbols and units) For some reason I got it into my head it was a DC motor.

Thanks to all who responded.

Is this repairable?

Where do I look to get a similar motor?

Now my brain has engaged I found the web-site with the specs of a similar unit

JS15 AC Motor



Cheers

 

[ericmark]

I have rewound motors on the Falklands where we could just not buy new. With 24V not too bad but with 230 volt the wire is so fine there is little chance of a manual rewind.

Go to most rewind shops with a motor under 5 HP and they will just give you a new one. Due to conservation rules normally new is cheaper than rewind. Sounds odd I know but old motors were not as efficient as the new so there is a government incentive to not rewind.

There is a chance you could re-wire so that you can reverse the field winding.

I am guessing slightly are reversing methods. It could be swap start and run or could be two windings connected in reverse but since the ebay diagram showed a capacitor I guess both windings are used.

Had a similar fault with a chair and it transpired the supply cable was damaged just as it entered the activator you could try pushing the cable sometimes it means the break is temp remade which would at least show where the fault is.

Meters may also help.