my customer is using below circuit to measure the DC offset of the 220VRMS AC voltage.
The OPA is TL074 and powered by ±12V, GND is referenced to DC bus's GND. When DC offset is 0.1V, the voltage on pin14 is 10.83V, almost the same as the +12V power rail(considering the headroom output voltage maximum should be lower than V+).
Why would that happen? Is it that the common mode input voltage is beyond recommended condition and TL074 already broken?