Food mixer Hall sensor ID

[yaks20]

Hi

I'm trying to repair a food mixer where the speed of the motor is detected using a hall sensor.

I have eliminated the components other than the microcontroller or the hall sensor. I figured the hall sensor is easiest to replace first. The markings on it are 137 033a.

I have swapped it with one with markings of 137 OH33 but it seems the control board isn't registering it and the motor operates at maximum speed regardless of the setting. I think it might be a pole issue?

I don't have a background in electronics, just an amateur.

Thanks in advance!

[fzabkar]

OH137, Ouzhuo, unipolar Hall effect switch IC, 4.5V - 24V, marking 137 + OH + xx:
http://www.secom.nazwa.pl/shopgold/pobieranie/OH137-E.PDF
https://mikroshop.ch/pdf/oh137.pdf

Judging from the photos in your other thread, "137" looks like a date code (2011, week 37). The part number code is probably "033a". The date code on the Sonix microcontroller appears to be "1132" (2011, week 32).

https://www.electronicspoint.com/forums/threads/hall-sensor-id.293299/

[yaks20]

Thanks! I'm a bit confused as part numbers 137, OH137 bring up the hall effect sensors as you've linked to. I can't find anything relating to '033a' anywhere online. Is there a way of identifying a suitable replacement hall sensor for the part i replaced? My replacement doesn't seem to detect the magnet rotating on the shaft or else the signal doesn't seem to be correct for the microcontroller.

Just to give you some background as to why I thought it was the hall sensor, it was because the motor would start with an erratic speed, speeding up and slowing down on its own. Then it would speed up to the point where i thought the mixer would damage itself. If i shorted out the pins coming from the hall sensor on the control board (either legs to ground) then the motor would slow down to a stop. On removing the short the motor would speed up again. I figured the hall sensor was not providing the correction voltage so that's why i thought it was faulty.

I clearly have no idea what i'm doing though!

[perieanuo]

hi,
you must check the motor first, if you have a problematic one (like one with problematic brushes), no electronic board will stabilise his speed
regards, pierre

[fzabkar]

I would start by determining the pinout of your sensor, and its supply voltage. Then I would disconnect the motor and power up the mixer. Now I would monitor the sensor's output pin with a multimeter while turning the motor slowly by hand (be careful of mains voltages). I would expect to see a digital voltage which switches between ground and the supply rail.