Another DX7 needing keyboard work, this one the second version, the DX7 iiD. Unlike the original DX7, which is elegantly designed for servicing with a hinged panel, the DX7 iiD features a nightmarishly large array of different sizes of screws and bolts, and you have to take dozens of them out to work on it, and take all the boards out through the bottom of the synth. The bottom of it actually has a warning: “CAUTION: DO NOT REMOVE THESE SCREWS.” If only.
Work done: Replaced 10+ keys and key springs, adjusted key tabs to level out velocity sensitivity, replaced patch memory battery
Notes on the DX7 keyboard: The DX7 keyboard uses long metal strips instead of springs and has three contact tabs under each key. The top tab (closest to the underside of the key) turns the note OFF, the middle tab is the one that the key’s movement directly pushes and the lowest tab is the one that detects the velocity. If the tabs for a key are positioned so that the middle tab is not making contact with the OFF tab when the key is not being pressed, it won’t sound the note when it is hit. If they are positioned so that the middle tab does not hit the lowest tab when the key is hit, the note will sound but there will be no velocity sensitivity. You have to get the lowest tab at the right distance and angle with respect to the middle tabs to make the velocity response even.