ph subsystem: Failed read probe

[Rob F]

Thanks, something definitely wrong with the I2C bus, the pca9685 runs the 0-10v and DC ports that's why those aren't working either.

I think there's two possibilities, a 3.3v to 5v converter for the I2C bus or the Pi. Any chance you have a volt meter and able to read a couple points on the board if I mark them in a picture?