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More Rodgers key whisker problems

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  • More Rodgers key whisker problems

    The e and f above middle c both play simultaneously whenever the key of either one is pressed.

    I opened the keyboard and when i press either key, I don't see any contact being made by the adjacent "whisker."

    Could it be a problem other than the contacts?

    Attached are two pictures. One is with the keys pressed, the other with the keys unpressed. The f key is the one with the broken whisker.

    Click image for larger version

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ID:	613823Click image for larger version

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ID:	613824

    Thanks,

    Tom

  • #2
    Tom,

    Check along the full length of the key. Is one of them warped, thereby causing them both to be depressed at the same time? Also, can you separate them when one is pressed, or do they appear to be firmly connected?

    Michael
    Way too many organs to list, but I do have 5 Allens:
    • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
    • Lowrey Heritage (DSO-1)
    • 11 Pump Organs, 1 Pipe Organ & 7 Pianos

    Comment


    • #3
      They actually are not physically stuck together. Pressing one does not press the other.

      The problem was initially intermittent, but now they both send midi on and off simultaneously, no matter which of the keys is pressed.

      Comment


      • #4
        More to this: the 'whiskers" for the keys look like they are contacting the bus bar correctly, i.e., when only one of the keys is depressed, only the contacts for that key touch the bus bar. Yet, both keys are activated. There is nothing that is visible to me that indicates why this should be happening.

        Comment


        • #5
          Originally posted by tbeck View Post
          Could it be a problem other than the contacts?
          I believe you are correct that it will not be the contacts. There is likely something else causing a connection between the wiring to the two keys. Possible something like a paper clip has lodged near the back of the keys of else there may simply be a short between the wires. Could also be an issue on the circuit board itself of course.
          http://www.nwmidi.com

          Comment


          • #6
            What is the model number of this organ? It could be a short in the keying system at the wiring coming from the key contacts or at the ganging board, if it has diode keying, or at the multiplexing board if it has a multiplexed keying system.

            Comment


            • #7
              Originally posted by John Kinkennon View Post
              I believe you are correct that it will not be the contacts. There is likely something else causing a connection between the wiring to the two keys. Possible something like a paper clip has lodged near the back of the keys of else there may simply be a short between the wires. Could also be an issue on the circuit board itself of course.
              I don't think it could be anything as large as a paper clip. Whatever it is I can't see it.

              - - - Updated - - -

              Originally posted by toodles View Post
              What is the model number of this organ? It could be a short in the keying system at the wiring coming from the key contacts or at the ganging board, if it has diode keying, or at the multiplexing board if it has a multiplexed keying system.
              It is a model 830.

              Comment


              • #8
                It could be as small as a drop of solder on the keyboard encoding boards--the wires from the keyboards go directly to the encoding boards.

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                • #9
                  Originally posted by toodles View Post
                  It could be as small as a drop of solder on the keyboard encoding boards--the wires from the keyboards go directly to the encoding boards.
                  How can I check for that? Any other troubleshooting advice?

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                  • #10
                    Use an ohm meter and with the organ off, measure the resistance between the whiskers of the two offending keys. A low reading indicates an electrical short. Then switch the ohm meter leads between the whiskers and measure again. If the measurement shows a short with both lead positions, well, you have a short somewhere. It could be a mechanical short, such as solder splash, or component short, such as a blown diode, transistor, IC, etc.
                    -Admin

                    Allen 965
                    Zuma Group Midi Keyboard Encoder
                    Zuma Group DM Midi Stop Controller
                    Hauptwerk 4.2

                    Comment


                    • #11
                      Originally posted by Admin View Post
                      Use an ohm meter and with the organ off, measure the resistance between the whiskers of the two offending keys. A low reading indicates an electrical short. Then switch the ohm meter leads between the whiskers and measure again. If the measurement shows a short with both lead positions, well, you have a short somewhere. It could be a mechanical short, such as solder splash, or component short, such as a blown diode, transistor, IC, etc.
                      I had a feeling it was going to be something like this. I don't have an ohm meter and I don't know how to use one. Can any kind of electric technician do this or do I need to find a specialist?

                      Is this the circuit board?
                      Click image for larger version

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                      Last edited by tbeck; 12-30-2017, 08:37 AM. Reason: add graphic

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                      • #12
                        That is the type of circuit board used to encode the keyboard for the multiplexing scheme. A short between the two notes on this board will cause the problem you described--both notes play on all voices for this manual when either note is pressed.

                        You probably don't need a meter to find the problem, a very close physical inspection will probably find the problem. The red wires at the top of this photo are the input from the keys. The two notes you have the problem with are in the middle of the board.

                        Check to see that the middle screw isn't touching two of the wire input pads or that wires soldered to those pads isn't shorting to that screw. Also look at the circuit just below that row of pads and the IC connection pads to see that nothing shorts any of those pads to each other.

                        A magnifying glass will help you a lot. This most likely just a physical problem, not an electrical one. Be sure to look at the other side of the board to see if the IC pins are shorted -- unscrewing the 3 mounting screws and maybe the two cable clamps should permit you to rotate the board up to see the component side of this board.

                        Comment


                        • #13
                          Originally posted by toodles View Post
                          That is the type of circuit board used to encode the keyboard for the multiplexing scheme. A short between the two notes on this board will cause the problem you described--both notes play on all voices for this manual when either note is pressed.

                          You probably don't need a meter to find the problem, a very close physical inspection will probably find the problem. The red wires at the top of this photo are the input from the keys. The two notes you have the problem with are in the middle of the board.

                          Check to see that the middle screw isn't touching two of the wire input pads or that wires soldered to those pads isn't shorting to that screw. Also look at the circuit just below that row of pads and the IC connection pads to see that nothing shorts any of those pads to each other.

                          A magnifying glass will help you a lot. This most likely just a physical problem, not an electrical one. Be sure to look at the other side of the board to see if the IC pins are shorted -- unscrewing the 3 mounting screws and maybe the two cable clamps should permit you to rotate the board up to see the component side of this board.
                          I can't see anything obvious. Possibly the screw is touching the pads, but I can't tell for sure. I think if I take that board off, I'll never get it back on again.

                          I suppose I'll have to get a technician here. I wonder if I should start looking into more permanent solutions. The age of the console is probably working against me. It's a shame, because I really love the way the keyboards feel.

                          Comment


                          • #14
                            You can unscrew that middle screw without completely removing it--that would move it away from the circuit board contacts. If that solves the problem, then you could just get a Nylon washer to put under the screw head to insulate it (or just remove it altogether--two screws will hold that circuit board in place without any problems.

                            I am not suggesting that you disconnect any of the wires, just permit the board to flip up while still attached. That organ should have German Laukhuff keyboards, which are very nice keyboards.

                            This really is a simple problem to fix--don't despair of getting it fixed.

                            Looks like the Rodgers dealer serving Puerto Rico is: http://www.centralmusic.biz/service-support/

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                            • #15
                              Thanks for the encouragement, Toodles. I'll keep trying.

                              I have spoken with that service rep in Florida. They have a technician who can come to PR, but travel expenses have to be paid by the customer (me). They also have a keyboard technician here they use for general maintenance. He was here when I first received the instrument. He lives on the other side of the island and he also charges travel and has a high rate, but I might have to resort to that if I can't fix it myself.

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