5 pole Motors stopped working

[PeteN92]

I have a Hornby m7 that has been an intermittent runner until recently on both DCC and DC. Now the motor has stopped working completely and when removing the motor and adding power to the motor contacts it seems dead. 

 

I ordered another motor and fitted everything. Working fine on DC and then re added the DCC and was working until I unsoldered the power leads to reverse them as the loco was going the wrong way. Now this motor appears dead too.

 

When I take both motors apart nothing seems to be burnt out nothing appears to be shorting where if shouldn't. And nothing looks melted. I'm really at a loss as to what is going wrong and how it could happen twice. 

 

The only thing I cannot see is the contact point on the motor where the brushes touch if the motor tag strips got too hot could something fatal have happened at this point ?

 

 

 

Cheers 

 

Pete

[WIMorrison]

try turning the worm slightly then reconnect the power, repeat this a few times and you may find that the motor starts in most places but not in one spot. This would mean that there is a dead sector which will probably mean another new motor but at least you will know the fault.

 

I have several 5 pole motors which display this behaviour

 

[AndyID]

Measure the resistance across the motor while slowly turning it. If it's a very large resistance (or infinite) a brush is not making contact with the commutator.

 

if it's a low value (tens of ohms) but becomes large at a particular angle one of the windings is open-circuit. The resistance should increase and decrease a bit as you turn the motor and windings are being connected and disconnected.

 

if you do not have a meter it's high time you did . They are not expensive and it will pay for itself in no time.

[nick_bastable]

why did you not reverse the direction on DCC via CV ?

[PeteN92]

Cheers guys it's reading as nothing on the multi meter I'm now wondering if the brushes have moved.

 

 

Where the windings come down onto the solder pads should the brushes be in contact above or below this disk that they sit on. Both motors seem to have the brushes below could this be the problem ?

 

Cheers 

 

Pete 

 

 

[PeteN92]

Problem solved the brushes had moved away from the commutator possibly due to having the soldering iron on a bit too long a quick adjustment and the new motor is back to life. Might see if the first one is suffering from the same issue .

 

Cheers 

 

Pete

[AndyID]

4 hours ago, PeteN92 said:

Problem solved the brushes had moved away from the commutator possibly due to having the soldering iron on a bit too long

 

Yes, you really need to be quick to avoid melting the plastic.

 

Apply a dab of flux to the motor's terminals. That should speed-up the process a lot. Presumably they are already tinned with solder but you should pre-tin the wires if they are not and even if they are it won't do any harm to tin them again.