I was connecting a PCF 8574 Remote 8-bit I/O expander for
I2C-bus which I was going to use to operate devices external to the Tivo ie. Video switch to switch between two Tivos onto one av input to TV. My test cct had worked some months ago but this time I was connecting it in a tider way and I suspect that have goofed in my connections.

I may try again soon to make this work time permitting.