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Roland Atelier AT15 pedal circuit diodes

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  • Roland Atelier AT15 pedal circuit diodes

    Gday Everyone.
    First, my apologies for the somewhat long winded post but I hope you can bear with me.
    It’s been a while since I have been on this forum or even played the organ.

    Had a few health issues among other things.

    So anyway I have a Roland Atelier AT15 which has sat unused for the last 3 years or so. Tried it out recently and discovered that there is an issue where the rhythm unit and the LCD display go nuts. I've discovered that this is only an issue when the pedal section is plugged in. Unplugged, the rest of the instrument works fine.

    I’ve even narrowed it down to the pedal section only, so if the circuit board for the pedals is unplugged and then the expression pedal etc is plugged back in, the instrument works fine.
    I discovered last night when I opened the pedal section up that we have had a mouse or 3 living in the pedal unit. Not for a while, but long enough ago for the urine to corrode some of the wires on the components.

    I’m not big on electronics but I have a friend who knows his way around pretty well.

    The board for the pedal switching is very simple. Just a membrane switch for each pedal and two small items (each pedal) which my friend reckons are Zener diodes.
    On some of these diodes, the mouse urine has corroded the lead (wire) on the diode.
    It will be a very straight forward job to replace these diodes if I can buy the correct ones.
    However I’ve looked closely at them with a good magnifying lens and I cannot see any identifying marks a all.

    So I’m hoping someone here might be able to help me.

    I’ve attached a picture showing the diodes They are only approx 2mm long so quite small. I've included a zoomed in version so hopefully it will show enough detail.

    Thanks in advance for any help, advice etc.

    Peter Marr
    You may only view thumbnails in this gallery. This gallery has 2 photos.

  • #2
    They are high speed signal diodes 1SS133. Substitutes are NTE 177 and 1N4935.
    Also clean the circuit boards well.



    • bollie7
      bollie7 commented
      Editing a comment
      Tucsondave. Just wanted to say thank you for the information once more.
      I have cleaned the boards and fitted a full set of new diodes. The instrument is back to full working condition.
      Thanks Peter Marr

  • #3
    Thanks for the fast reply and the information. Greatly appreciated.