If the amp works with the relay bypassed, It's not likely that a MOSFET failure is the cause of the DC offset. As the Dude said, measure the DC on the output with the relay bypassed,ore better remove that link and check on pin 1 of the relay which s the signal OUT from the MOSFETS. Also measure the voltage across the relay coil. Do not connect a load until you resolve the issue, especially with the relay bypassed. One we have that info we can suggest the next step.
One caveat, I've seen these with one slightly low gain FET which can be tricky to diagnose. You need a dummy load, signal generator and a scope, run to full output and look for asymmetrical clipping. The symptom is the the amp cuts out, but only at high volume, as the average voltage on the output is not close to zero so the power supply is shut down and the error LED on the board lights up.
Lastly, I think my suggested figure of 3.3mV is too high for idle current above (post #97) is too high. 1mV is more like it.
One caveat, I've seen these with one slightly low gain FET which can be tricky to diagnose. You need a dummy load, signal generator and a scope, run to full output and look for asymmetrical clipping. The symptom is the the amp cuts out, but only at high volume, as the average voltage on the output is not close to zero so the power supply is shut down and the error LED on the board lights up.
Lastly, I think my suggested figure of 3.3mV is too high for idle current above (post #97) is too high. 1mV is more like it.
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