I have a 500w motor that was giving me a Hall Sensor Error. I opened it up and noticed that 1 of the 3 Hall Sensors was reading 3.31v and was not cycling from 3.31v to 0.1v as it should. I ordered 6 Honeywell SS41 Hall Sensors and replaced all 3. The middle sensor now reads only 1.96v and doesn't change at all. I unplugged the cable and checked the voltage that was coming from the pin on the controller, and it was showing 3.31v. I plug the cable back in and it drops again. I thought it could be a short so rigged a cable from the controller ground/3.31v pin and direct-attached it to the Hall. Once the cable connected to the Hall Sensor it dropped down to 1.96v I replaced the sensor twice and the same thing happens. The only thing else on the board is Bi-Poler Tansisters labeled 2n5551 bf 011 that @MaxHeadRoom was able to identify. I'm just starting out and still brand new at this. What could cause this issue, just maybe some bad hall sensors, or a transistor could cause this? Any help would be great. Thanks

 

Where are the pull-up resistors located, you may have a bad/open one on that sensor?
Max.

 

@MaxHeadRoom - Here is a photo I took of the board after the middle hall sensor was removed. There was a huge amount of silicone covering everything so I needed to scrape it off. The problem was the same before I did that and I did repair the connection and tested everything to make sure I did it correctly. The senors where I'm holding are the Hall sensors and the bottem are the transistors are.

 

The ss400 series are open collector, but I don't see any other components there, resistors etc?
Max.

 

It's a simple board. 3x Honeywell SS41 Hall sensors on the top and 3x transistors 2n5551 bf 011 on the bottom.

 

That's the only things on this board

 

Those are open collector, and if you look at the spec sheet, every example of interfacing shows a collector/pull up resistor.
Max.

 

So could this could be a good possible reason on why the voltage drops when I connect a 3.31v power source to the Hall Sensor leg?

 

When your testing do you have a magnet on the sensor?

 

@shortbus Yes, correct.

 

@shortbus Yes, correct.

Is the polarity of the magnet correct? Some halls are positive some are negative.

 

@shortbus I believe so. The other two that I install switch back and forth from 0.1v to 3.31v like the original did.

 

@shortbus I believe so. The other two that I install switch back and forth from 0.1v to 3.31v like the original did.

Without being there it's hard to test. Are all three mounted in the same orientation?

 

@shortbus Yeah, they have a slot they fit into and they can only go in one way

 

... Are all three mounted in the same orientation?

Evident from the first picture is that the middle sensor has to be mounted in reverse orientation to the board in regard to the other two. The middle sensor seems to have its signal pin on the top position, where the other two have their signal pins on the bottom position.

 

Those are open collector, and if you look at the spec sheet, every example of interfacing shows a collector/pull up resistor.
Max.

Hi all, I have a same motor configuration, 3 hall sensors and 3 open collector bjt 2n5551, btw the lack of a pull up resistor make me think they are not used, I will try to connect a different board where I have only 5 wires.
Can anyone explain why there are some sort of transistors on the motor, usually there are only the 3 hall sensors to detect rotor position