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Pedal note stuck on - Wurlitzer 4373

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  • Pedal note stuck on - Wurlitzer 4373



    I have bought a near pristine 4373 but it has a few problems. The first is that one of the pedals is stuck on. If I press one of the other pedals, the note is played properly. As soon as I release, the stuck on note returns. I opened up the back and looked at the contacts. With the contacts apart, the note is heard. When I depress the pedal and contacts touch, the note is silent.




    Any ideas??




    Any help appreciated as i really want to get this unit working.




    Thanks!


  • #2
    Re: Pedal note stuck on - Wurlitzer 4373



    It sounds like the pedals might be scanned as a matrix. If so, possibly one of the "disconnect" diodes is shorted. These diodes prevent sneak paths when two notes are pressed simultaneously. If the manuals and the pedals are both scanned together, the problem COULD possibly be a bad diode or a short someplace EVEN up in the manuals, even if those play correctely.




    The pedals are probably rigged to sound only a single note... Since pressing the pedal kills the sound, the actual problem might be on an adjacent pedal OR in the adjacent one of the matrix however it is scanned. Check ALL the contacts... and again, it could be a disconnect diode of the matrix on an adjacent note or scan order.




    Also insulation may have broken down someplace or a piece of conductive material shorting contacts someplace.




    If I had schematics, it would take minutes to find this problem...


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