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Suitable substitute part

Discussion in 'Troubleshooting and Repair' started by partyanimallighting, Oct 16, 2014.

  1. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Hi guys,

    I'm trying to stockpile some spare parts for some moving heads that I have in rental. One of the parts is a small PCB which picks up a magnetic field from magnets installed on the Pan and Tilt gears via a Hall Effect Sensor Part No. W41FC. I'm finding all sorts of substitutes online but want to be sure that what I'm buying will work as a replacement. The attached picture is of the PCB with two of the sensors, one to pick up the magnet clockwise and the other to pick up counterclockwise. Any ideas? Geni Mech 5 Pan Magnetic Sensor W41FC 002.jpg
     
  2. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Here's the datasheet.
     

    Attached Files:

  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
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    Nov 28, 2011
    What replacements are you considering? Can you link to data sheets for them?
     
  4. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Hi Kris. I attached a data sheet previously. The pcb in question only has two of these sensors on it so, if any of them fail, I can purchase the sensor or a suitable substitute, then I can simply remove the pcb, swap out the sensors and replace the pcb.
     
  5. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
    1,266
    Nov 28, 2011
    OK, if you can get the identical part, what's the problem?

    I thought you were asking for suitable non-identical replacements. In that case, can you post the data sheets of the non-identical replacements you're considering? Otherwise I don't know what you're asking.
     
  6. Bluejets

    Bluejets

    3,452
    698
    Oct 5, 2014
    From the data sheet it looks like a specialised part as it has 2 open collector outputs, quite a high current handling capability , frequency generator,
    other things also.
     
  7. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Hi guys, I have two suppliers that I normally buy parts from in the US but both suppliers don't have the part listed at all. So I'm looking for a suitable substitute that I can use. As far as my actual knowledge is concerned, I'll be guessing as to what part can be used as a substitute. Will any Hall Sensor work?
     
  8. Bluejets

    Bluejets

    3,452
    698
    Oct 5, 2014
    As I outlined above.......no.
     
  9. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    8,393
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    Nov 28, 2011
    It looks like the only unusual things about the original Hall sensor are (a) it has a maximum output current rating of 400 mA, but I doubt that the connected circuitry would require this, and (b) it has two complementary outputs, but from the markings on the circuit board, it appears that the design may be using only one of the outputs anyway. Check this by looking at the tracks from the sensors to the socket on the board. If only the OUT1 pin is used (the one next to the positive supply pin), then it's compatible with a standard Hall switch.

    It doesn't contain a "frequency generator"; I think those words in the data sheet refer to the fact that it will generate a frequency if exposed to a rotating magnet. Well, duh!

    The original claims to be temperature-compensated, but given its wide magnetic tolerance and hysteresis, and the application, I don't think that's important.

    The original one is unipolar, activated by a south pole only, but AFAIK you could also use an omnipolar device.

    The original device has a wide power supply voltage range, but according to the PCB markings, it's being operated at 5V so that's not an important factor either.

    Its physical characteristics (e.g. thickness, location of the sensor) may be significant, especially if the sensor is clipped into some precise fitting. If not, you could try a replacement sensor in a known good unit. It's very unlikely that any harm would come from it. You want one that will activate at (or slightly below) 150 gauss (15 milliteslas). Here's a Digi-Key filter specification: http://www.digikey.com/product-search/en?FV=fff4001e,fff80480,4000db,40308a,40393b,a401cc,a401d7,2dc07df,2dc08be,2dc0ef2,2dc11b6,2dc17f2,2dc1818,2dc1819,4500011,450002f,4500188,4500351,450056a,450080f,10180001,10180043,1018004c,10180050,10180051,10180141,101802a8,101802ab,101802b1,101802e4,101802e5,1180000c,1180000d,11800019,142c02ca,142c03c0,142c09c5&ColumnSort=1000011&stock=1&quantity=1

    Any of those should be suitable. If you want a specific suggestion, try the cheapest one: http://www.digikey.com/product-detail/en/US5781EUA-AAA-000-BU/US5781EUA-AAA-000-BU-ND/1485720. Download the data sheet to work out the pin connections because they're different from the original. I think you need to mount it wide face downwards, because the back is sensitive to the south pole.

    Good luck!
     
  10. partyanimallighting

    partyanimallighting

    278
    2
    Oct 22, 2012
    Sorry about this late reply. The problem is, once I'm finished using these units for any jobs and they don't give me any problems, they're packed away in the warehouse until the next job. One of these did fail a couple years ago (not failed actually, it was broken off the pcb by the magnetic swing arm when a worker handled it roughly) and I swapped it out with a completely different hall sensor with 3 legs (the W41FC has 4 but 1 is not connected on the PCB) from a different brand of unit and it worked fine. So I think basically any Hall sensor will work but I'm just looking for something as close as possible to the original W41FC's values. Once the sensor is replaced, the legs are simply bent into place so that the magnet on the gearwheel or magnetic swing arm passes in close proximity to the sensor, which reads it and stops the rotation of the motor (I guess??!!) So you think any of those that you listed above will work fine? If so, I'll order a few and once again, thanks for all the assistance. Geni Mech5 W41FC Hall Sensors and magnets.JPG
     
  11. davenn

    davenn Moderator

    13,260
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    Sep 5, 2009
    HI there
    Unfortunately Kris is no longer with us :(
    all I can suggest is for you to try his suggestions

    Dave
     
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