Roland TR-707

Posted on Feb 7, 2014

Hack the pitch shift of the crash and ride by lifting pin 10 of the TC4040 binary counter and insert your own clock in (or just whack it with an additional clock source). This could be any suitable signal you pick up from the TR itself. The other sounds do not have a counter for adress select (like IC 34 and IC35 (BD-midTom and HiTom-Tambo

Roland TR-707
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urin). Here adresses are selected directly from IC30. Both these IC`s are connected to the same adress lines, so unless you lift/cut traces these sounds will probably be bent together. CE (chip enable) selects witch ROM reacts to the datalines. CE can be used as bend points. Notice the RA3 and RA4 (resistor arrays). These are simple R/2R DAC`s. The inputs can be fed signals that will be treated as digital audio and be converted into audio. You can also do this at the D0-D7 lines between IC35 and IC`s 36-37. Well, it`s a long story, loads could probably be done after some study. If you want to implement your bends inside the TR-707 itself, I suggest to start with a selectrion of data lines. Or go over the top on a breakout box. seperate pitchbend can be done on the other sounds, but some sound are pitchbent together by the same knob. These would be sounds in combined ROM pairs as outlined earlier. It`s clocked with a crystal though, a simple pot here may not be optimal. Maybe Diabolical removed the crystal and made his own clocks. Search for a (CD)40106 clock or oscillator schematic, might do the trick. they sayd: "Because of the digital nature of the 707 a clock modifier is needed to change the sample playback rate. Doing this mod for each drum sound would require individual circuits to be added, however to minimize the part count a 558 Quad 555 can most likely be used. " "On the TR-707 the open and closed hats sounds use...

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