It maybe obvious but haven't seen it mentioned yet. Have you checked each commutator segment to the shaft? From what I gather in this thread, it sounds like you have replaced the copper part of the commutator, the bars. If that is what you did you may have a short to the shaft/armature. This would keep it from running.

 

If a 12v motor It should output around 5-6v at that rpm.
You either have some error in the fitting of the com or wrong connections.
That is if the coils are intact with no damage.
Max.

 

If a 12v motor It should output around 5-6v at that rpm.
You either have some error in the fitting of the com or wrong connections.
That is if the coils are intact with no damage.
Max.

My question is "how to check for wrong connections"

 

The Utube in post#18 shows the com orientation and the coil connections, as long as each section has the start end end of adjacent coils.
Check for com shorts segment to segment and to GND.
Max.

 

If a 12v motor It should output around 5-6v at that rpm.
You either have some error in the fitting of the com or wrong connections.
That is if the coils are intact with no damage.
Max.

Or couldn't it be that the end cap with the brushes is not in the correct position with regard to the field magnets.

 

Or couldn't it be that the end cap with the brushes is not in the correct position with regard to the field magnets.

Thanks. Yes, did check the brushes and they are in the correct position i.e. same axis as the poles. Tried it again and the motor does rotate about 1/2-1 turn and stops. Wonder if there is something sticking and preventing rotation. Also visually checked the connections i.e. start of 1 coil goes to finish of the next. If it were not correct, would the motor rotate 1/2-1 turn? Just wondering.

 

Thanks. Yes, did check the brushes and they are in the correct position i.e. same axis as the poles. Tried it again and the motor does rotate about 1/2-1 turn and stops. Wonder if there is something sticking and preventing rotation. Also visually checked the connections i.e. start of 1 coil goes to finish of the next. If it were not correct, would the motor rotate 1/2-1 turn? Just wondering.

Is there a simple way to check the coil connections i.e. if start connected to finish of 1 coil to the next?

 

Connect L.V. power across each coil and test coil polarity with a compass or P.M. magnet.
Max.

 

Thanks.
Had tried with P.M. Not come across P.M. with N, S marked. So my P.M. attracted to each of the 3 coils, so could not determine polarity, since it attracted to each of the 3 coils the same way! May be a compass is better? Also, this is a 18VDC motor, so assume that 4VDC across each coil for this test is OK?

 

trying to design a shovel to dump fine sand from A to B. The trolley/truck that moves the shovel is already built - now trying to design the shovel to scoop the sand at A, then move to B (about 10' away) and dump the sand. This is a miniature shovel i.e. 18" wide by 12 " long. Battery operated.

 

Check for shorts between segments and check the coil continuity and separation from each other.
How many segments and is it oriented right?
Max.

Max

An odd number of armature coils is not uncommon, these 3 seg are usually used in small toy motor applications.
Three segment example.

Max.

 

Hi MaxHeadRoom: On a slightly different topic I have 4 coils fed with 90 deg phase shifted current and 2 Hall sensors. This is from an old Video player. Trying to replace the analog cct but not sure how. Please help

 

Bit more info needed, can you post a pic?
Max.

 

Bit more info needed, can you post a pic?
Max.

Thanks.
Here is a pic. The 2 Hall Sensors are at the top centre.