Hi,
please be sure to use the right connections. There are different connections for A and mA.
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If connections are right.
Where do you know that you really have 1ADC or 400mA DC?
the relation is not equal: 1.00A / 0.166A = 6; 400mA / 54mA = 7.4
(Therfore i don´t expect the voltage reference to be broken)
If the shunt burnt, then i there should be higher readings than expected. This isn´t the case.
Maybe there is a fuse in series to the power path....
The meter doesn´t show an overflow, so i expect the ADC to be OK.
Therefore i expect the failure somewhere between power path and ADC. Maybe there is an RMS_to_DC circuit.... Check the input and output voltages .
Good luck
Klaus