Hi George Vernon,
Are you referring to the CLK pin or the SCLK pin. I suspect you are referring to the CLK pin since the devices work correctly when you lift the pin.
Is each AD7794 using its own internal clock or is the internal clock of one device used to drive all 6 ADCs?
On power up, you should perform a reset by writing 32 1s to the parts. This will reset all devices to their default state. In this state, each device uses its own internal clock and the clock is not made available externally.
If each ADC is using its own clock, then it is not necessary for the CLK pins to be connected. However, once the ADC’s clock is not made available externally, it is ok to connect the CLK pins together.
If the clock of one device is used to clock the other devices, then 5 of the devices should first be programmed to accept an external clock. Following this, the sixth device should be programmed to output its clock on the CLK pin.
Thanks and Best Regards,
Chris