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Lowrey D450 sticking Orchestral notes

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  • Lowrey D450 sticking Orchestral notes

    When the Orchestral Symphonizer is switched on random notes will stick and play as you go up/down the keyboard.
    Organ had other issues, but re-seating the IC's in the Central Processing fixed those (guess there was corrosion on the sockets).
    Has anyone else run into this "Sticking note problem" before?

  • #2
    Yes, not on a D450 but on later Lowreys and many other digital instruments. Causes have included faulty ribbon cables, unseated cables and ICs and, in one case, a ribbon cable with a board mounting screw driven through it - a Lowrey NT400 Heritage. Occasional hangs and lock-ups with no apparent cause on digital instruments from Yamaha, Kawai and Technics (and probably others). Usual computer remedy "Turn it off and back on again!"
    It's not what you play. It's not how you play. It's the fact that you're playing that counts.

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    • #3
      Originally posted by andyg View Post
      Yes, not on a D450 but on later Lowreys and many other digital instruments. Causes have included faulty ribbon cables, unseated cables and ICs and, in one case, a ribbon cable with a board mounting screw driven through it - a Lowrey NT400 Heritage. Occasional hangs and lock-ups with no apparent cause on digital instruments from Yamaha, Kawai and Technics (and probably others). Usual computer remedy "Turn it off and back on again!"
      Have re-seated every IC on the processor board but still get that sticking note in the Orchestral symph!
      Checked all cables as well but still no progress.
      Got an issue with the Genius, but that is further down the line!
      Need to find out why notes play randomly in the Orchestral first!!

      Comment


      • #4
        The Orchestral Symphonizer is an 8 voice system. As you play notes, it cycles through the 8 notes available. If you have a "voice" problem, it may seem to be a random key but it's likely a bad voice that is called up on different keys as it cycles. Each voice has dividers, envelope generators and a lot of diodes. You first need to determine which voice it is and use typical troubleshooting to solve it.

        If you play one note at a time, when you find the defective note, continue one note at a time and the next defective note should be the eighth note.

        Geo
        Last edited by geoelectro; 04-13-2018, 09:29 AM.

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        • #5
          Originally posted by geoelectro View Post
          The Orchestral Symphonizer is an 8 voice system. As you play notes, it cycles through the 8 notes available. If you have a "voice" problem, it may seem to be a random key but it's likely a bad voice that is called up on different keys as it cycles. Each voice has dividers, envelope generators and a lot of diodes. You first need to determine which voice it is and use typical troubleshooting to solve it.

          If you play one note at a time, when you find the defective note, continue one note at a time and the next defective note should be the eighth note.

          Geo
          Seems to be on all Orchestral settings and the note sticks with each setting of Vibes, Clarinet, Trumpet or whatever and is not in an 8 note pattern (as in 8 bits per microprocessor).
          Somewhat confusing at this point.

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          • #6
            Swap IC 18 with IC 19 on the CPU board to see if anything changes.
            td
            Servicing electronic organs since 1969.

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            • #7
              Originally posted by tucsondave View Post
              Swap IC 18 with IC 19 on the CPU board to see if anything changes.
              td

              Tried that already but no difference!
              Nice thing about Lowrey is the redundant use of chips.

              Any other idea's?

              Comment


              • #8
                Originally posted by mnow View Post
                Seems to be on all Orchestral settings and the note sticks with each setting of Vibes, Clarinet, Trumpet or whatever and is not in an 8 note pattern (as in 8 bits per microprocessor).
                Somewhat confusing at this point.
                When you first turn on the organ and play one note at a time it should cycle through the eight notes. (Doesn't matter which sound is selected) Once you get through them the "pattern" will fall apart as you continue to play and especially when playing multiple notes at a time or reverse direction.

                CPU BD:

                IC 24 & 25 produce the tones but I believe those tones run continuously. If I had a stuck note I would test each output of those two IC's to identify which voice was sounding. (Audio tracing)

                IC 26 & 27 produce frequencies for controlling the envelopes for the 8 voices. An envelope problem would be suspect. You could swap 24 & 25 with 26 & 27. They are the same IC but perform very different jobs. If swapping these 4 ICs don't change the symptom then I would move to the Brass Percussion Generator Bd.

                Geo

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                • #9
                  Originally posted by geoelectro View Post
                  When you first turn on the organ and play one note at a time it should cycle through the eight notes. (Doesn't matter which sound is selected) Once you get through them the "pattern" will fall apart as you continue to play and especially when playing multiple notes at a time or reverse direction.

                  CPU BD:

                  IC 24 & 25 produce the tones but I believe those tones run continuously. If I had a stuck note I would test each output of those two IC's to identify which voice was sounding. (Audio tracing)

                  IC 26 & 27 produce frequencies for controlling the envelopes for the 8 voices. An envelope problem would be suspect. You could swap 24 & 25 with 26 & 27. They are the same IC but perform very different jobs. If swapping these 4 ICs don't change the symptom then I would move to the Brass Percussion Generator Bd.

                  Geo
                  Did try swapping 24 and 25 with no difference, but will switchout 26 and 27 with those as well and see what happens.
                  Thanks for the idea!!!

                  Comment


                  • #10
                    The outputs of IC 22 - 27 on the CPU board all produce a signal and change in frequency as keys are pressed. The data channels all seem to be working but the CSWR pins all have just a high signal (I.E. no data being sent).
                    IC 15 - 16 seem to operate differently (the chip select decoders). IC 16 has some form of clock data on it's output while IC 15 just has high output. Have swapped the chips, but still no go! Any idea why the POP chips (IC22 - 27) are outputting
                    signal?

                    Comment


                    • #11
                      Originally posted by mnow View Post
                      The outputs of IC 22 - 27 on the CPU board all produce a signal and change in frequency as keys are pressed. The data channels all seem to be working but the CSWR pins all have just a high signal (I.E. no data being sent).
                      IC 15 - 16 seem to operate differently (the chip select decoders). IC 16 has some form of clock data on it's output while IC 15 just has high output. Have swapped the chips, but still no go! Any idea why the POP chips (IC22 - 27) are outputting
                      signal?
                      After re-reading the manual, it is starting to look more like the PIC chips in the INTERFACE circuit are not controlling the keyer circuits in the symph circuit!
                      Correct me if I am wrong, but it seems like the POP chips always output signal, and is is the function of the PIC chips to turn the sound on or off?

                      Comment


                      • #12
                        btw can you reprogram the chip or add a usb so you could run hauptwerk?

                        Comment


                        • mnow
                          mnow commented
                          Editing a comment
                          How to reprogram the PIC?

                      • #13
                        The chip that makes the sound.
                        Last edited by musicgeek854; 07-27-2019, 12:17 PM.

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                        • mnow
                          mnow commented
                          Editing a comment
                          These are Lowrey specific IC's! No way to re-program!!

                      • #14
                        Thanks! but could you add drawbars? Also I think the orchestral symphonizer has a bad connection. Where to check first?

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                        • mnow
                          mnow commented
                          Editing a comment
                          That is my question also!

                      • #15
                        Drawbars would probably be easy to install. I'd buy the same volume sliders that the organ uses for other features or leave the tabs in so I have presets.

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                        • mnow
                          mnow commented
                          Editing a comment
                          The PIC I am referring to is not a pic micro!! It is what Lowrey refers to as a "Peripheral interface chip".
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