Hall sensors testing shows all at a fixed number

[vwrado]

I have been trying to figure out the hall sensor error that I got on a motor that shows hall sensor error on 3 different controllers. The motor is from a super 73 rx. I have disassembled the motor and used a multimeter to test all three sensors and two sensors yellow and green and shows a constant 4.98V while the blue shows constant 3.98 and doesn't change when I rotate the motor. I have sucessfully tested a hall before and can see that it usually switches near 0 and up to almost 5. So this is new to me. Is it possible that all hall sensors are bad? I thought it was a wiring short somewhere but couldnt find the short anywhere. Does anyone have any insight on if they think its all 3 sensors that are bad or am I looking in the wrong spot?

here is a picture of what I am looking at

 

[amberwolf]

Are you testing hte sensors using a pullup resistor (5k-10kohm) to their supply voltage, on each signal line? If not, the signal won't be valid.

Or with the hall sensors plugged into a powered-on controller (the contorllers have these pullups built in).


If, with pullups in place, you have sensors that do not toggle between around 0v to around 5v as magnets pass them, the sensors have probably failed and would need to be replaced.

The usual reason for them to fail is motor cable damage that shorts phases to hall signals or hall power; this usually blows up both motor halls and controller internals. Or overheating of the motor.


For further info, there are many threads about testing hall sensors, replacing them, part numbers used, sources for the parts, etc., if you poke around.

 

[fechter]

It seems like all the sensors are bad. That's pretty hard to do, usually they go one at a time. If the 5v supply line made contact with a phase wire, that would do it. Any recent crashes?

 

[TommyCat]

Depending on the test points... why not just a simple loss of 5 volt supply to the sensor board? Not particularly mentioned, but I'd check for that first.

For further info, there are many threads about testing hall sensors

Testing BLDC motor's Phase Wiring - Hall Sensors and Wiring. - Electricbike.com Ebike Forum
... for one.


Regards,
T.C.

 

[vwrado]

I tested it with the controller plugged in.

I will try the 5v directly to the power supply next.

 

[TommyCat]

Just check the RED and BLACK input wires lower right for 5vdc whist connected to controller and powered up...

 

[fechter]

Yes, be sure to also check the black wire to make sure it's really at ground. If the ground connection is broken, it could make all the sensors read high.

 

[vwrado]

A lot of my testing is starting to not make sense to me. I have tested the following:

red and black wire on the hall sensor plug where the controller connector plugs into the motor (6 pin plug) I get 4.5v which seems normal
then red from the connector to the black wire on the motor where the pcb board is and get .24
then red from the connector to the red on the motor and I get a constant 4.5v
Black at the connector to the black at the motor - 4.23v
black at the connector to red on the motor - 0

Is this a short somewhere or a chip on the pcb burned?

 

[amberwolf]

A lot of my testing is starting to not make sense to me. I have tested the following:

red and black wire on the hall sensor plug where the controller connector plugs into the motor (6 pin plug) I get 4.5v which seems normal
then red from the connector to the black wire on the motor where the pcb board is and get .24
then red from the connector to the red on the motor and I get a constant 4.5v
Black at the connector to the black at the motor - 4.23v
black at the connector to red on the motor - 0

Is this a short somewhere or a chip on the pcb burned?

Sounds like a broken ground wire. You might want to turn all power off and measure the wire continuity for each wire from the motor to the controller.

 

[TommyCat]

Check to see if the correct polarity is maintained thru the hall connector for the 5vdc.
I.E. RED to RED and BLACK to BLACK, verify polarities with meter.