Hi everyone!

I'm working on a circuit-bending project involving a Yamaha PSS-47, and I'm running into some strange behaviour with a 74HCT4051N multiplexer.

My setup:

* Yamaha PSS-47 with its ROM data lines exposed for circuit bending.

* LTC1799 oscillator replacing the original ROM clock.

* ESP32 controlling a 74HCT4051N.

* The 4051 is used to sequence different ROM data-line connections.

I'm connecting the Y0–Y7 pins of the 4051 to different ROM data lines, with the common Z pin connected to my bend point. The ESP32 controls the address pins (A, B and C).

The strange behaviour:

The circuit bends actually work better when I disconnect VCC (pin 16) from the 74HCT4051N.

When I connect 5V to VCC, the bends stop working properly. With VCC disconnected, I get much more interesting and functional bends.

I've also been looking at the signals with an oscilloscope. When zooming in on the signal, I can clearly see the high-frequency LTC1799 clock.…