Hugo Holden
Veteran Member
I came across the attached modification, not factory by the look of it, pin 10 (the preset input of a 74LS74) of u15 was cut (red X in the attached diagram) and connected to pin 1 (green wire in diagram), ultimately connecting the clear and preset inputs of the same flop flop together. Previously pin 10 was connected to a pull up resistor, and the clear inputs are connected to a power turn on low pulse, at power up, until a capacitor charges.
Does anybody have any idea what this modification was for ? was it to make the keyboard go into local mode at power up, and if so, what application could that have had ?
Does anybody have any idea what this modification was for ? was it to make the keyboard go into local mode at power up, and if so, what application could that have had ?