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Thread: Lowrey D450 sticking Orchestral notes

  1. #1
    ppp Pianississmo mnow's Avatar
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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?

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    Moderator andyg's Avatar
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    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!"
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    ppp Pianississmo mnow's Avatar
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    Quote 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!!

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    fff Fortississimo geoelectro's Avatar
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    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 at 04:29 PM.

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    ppp Pianississmo mnow's Avatar
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    Quote 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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    ff Fortissimo tucsondave's Avatar
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    Swap IC 18 with IC 19 on the CPU board to see if anything changes.
    td

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    ppp Pianississmo mnow's Avatar
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    Quote 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?

  8. #8
    fff Fortississimo geoelectro's Avatar
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    Quote 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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    ppp Pianississmo mnow's Avatar
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    Quote 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!!!

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