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Help me identify this part and find a replacement?

Discussion in 'Datasheets, Manuals and Component Identification' started by JGAN, Jan 5, 2013.

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  1. JGAN

    JGAN

    9
    0
    Aug 23, 2012
    Hey guys,
    The selector dial on my stereo receiver was malfunctioning, and I need to find a replacement part. I think it is either a rotary switch or rotary encoder, made by Mahsushita (now Panasonic). The only other markings on it are "012" and below it "12B" but I have not been able to find a datasheet on it. The base is about 15mm on each side, and the dial itself has one flat edge and a diameter of about 5.95mm. Also, it has no stop and turns infinitely.

    Here are some pictures and the schematic symbol also: http://goo.gl/8X38l

    Anybody know for sure what it is and what a suitable replacement part would be?

    Thanks,
    JGAN
     
    Last edited: Jan 5, 2013
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    It sounds like a rotary encoder, however are you sure it's the problem.

    An analogy would be going out and looking for a new key if I put my key in the car and it failed to start...

    If it is the rotary encoder, it may be non-trivial to find a replacement. I'd start by looking at rotary encoders and seeing if you can find a physically similar part. Then look at the datasheet to see if they are likely to be the same.
     
  3. JGAN

    JGAN

    9
    0
    Aug 23, 2012
    I'm pretty sure it's the switch not a firmware problem or anything. Either way, I doubt it is an expensive part to replace so I'm ok with it not being the problem.

    One more clue is that it gives little clicks as it rotates and selects a new input.
     
  4. JGAN

    JGAN

    9
    0
    Aug 23, 2012
    Actually I just opened the case and it is a rotary switch, not encoder (there is no PCB). How do I determine how many ways, poles, and positions it has to find a suitable replacement?
     
  5. davenn

    davenn Moderator

    13,710
    1,911
    Sep 5, 2009
    the cct symbol would tell you that, looking at it suggests its a single pole and 2 position, but the trick is its probably connected to a processor chip which will determine rotation pulses and direction as one switch will probably be open when the other is closed and they may open and close alternately, one switch leading or lagging the other depending on direction of rotation

    just my thoughts :)

    test it with your meter

    Dave
     
    Last edited: Jan 6, 2013
  6. JGAN

    JGAN

    9
    0
    Aug 23, 2012
    Now I don't really know much about what I'm talking about, but from what I have looked at online, are the number of contacts determined by poles*positions? If so, would this be a two pole, two position rotary switch (4 contacts)?
     
  7. davenn

    davenn Moderator

    13,710
    1,911
    Sep 5, 2009
    no.... see your circuit symbol, there are only 3, Three contacts, Pins 1,2 and 3
    technically its 2 x 1 pole 1 position but 2 of the poles are connected together commoned

    Dave
     
  8. JGAN

    JGAN

    9
    0
    Aug 23, 2012
    I'm having trouble finding a 2 pole 1 position rotary switch on Mouser and Newark like the one I have. Am I searching correctly? How do i search for 2x1 pole?
     
  9. davenn

    davenn Moderator

    13,710
    1,911
    Sep 5, 2009
    its a very specialist switch you have there
    maybe it was made specifically for that bit of gear ???

    no its a 1 pole 2 position sort of

    I dont know

    Dave
     
    Last edited: Jan 6, 2013
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    It's such a special switch they give it a name... rotary encoder.

    See here.

    Of course, I can't be 100% sure, but if it was connected to a knob that was supposed to turn around and around (as opposed to having 2 positions) the evidence weighs very strongly on the side of a rotary encoder as opposed to a 2 position switch.
     
  11. JGAN

    JGAN

    9
    0
    Aug 23, 2012
    I think you're right. Looks like a mechanical incremental rotary encoder. However, I know it is a 12 position, but how many channels? Two? Because the two channel encoders I have looked at only have 3 pins, not 4.
     
  12. davenn

    davenn Moderator

    13,710
    1,911
    Sep 5, 2009
    well its not a 12 position as you have already stated it rotates continuously
    if it was 12 position it would have 12 switched positions plus a pole position contact
    and wouldnt rotate more than 12 clicks

    if you look at the circuit symbol it shows only 3 contacts, that 4th contact may just be a case GND connection

    Dave
     
    Last edited: Jan 7, 2013
  13. JGAN

    JGAN

    9
    0
    Aug 23, 2012
    Yes, I meant 12 detents.

    Would I have to bend pins to get a 3 pin rotary encoder to work? I don't mean to be lazy or anything, but I'm not very good at this. Could you link me to something that would work?
     
  14. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,448
    2,809
    Jan 21, 2010
    Presuming the existing rotary encoder still works at least a bit, you can use a multimeter to determine which lead is common and which are the quadrature outputs (it is possible that you have no common input, but the schematic suggests otherwise).

    Then get another rotary encoder , connect it up the same way (perhaps with flying leads) and see if it fixes the problem.
     
  15. nepow

    nepow

    99
    1
    Jul 18, 2011
    encoder switch

    If youve managed to take it apart without damage, have a good look at the contacts for any signs of wear... as already suggested, a multimeter will identify the switching arrangement and reveal any deffects etc. Personaly I've never known one fail
     
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