Your lowest voltage is 127.5mV.
You want to adjust the value of the others to match this value.
The easiest way to figure out what value you need is to get
a 200k 20k trim pot and install it across the Riv resistors one at
a time. Adjust the trim pot until the voltage reads 127.5mV.
Unsolder the trim pot and measure the resistance. Find the
closest standard value and solder this on top of the Riv you
just measured. Repeat until all the Riv read 127.5mV.
This process will account for tolerance in the Riv resistors
and the tolerance of the PCM1794a.
Edit: changed trim pot value.
The expected values of the parallel trim resistor
will be in the 1k to 10k range.
Edited by Avro_Arrow - 5/11/14 at 4:26pm