Ammeter problem

1.Problem description:Plug the 30mA ammeter into the power supply and make a test cut. When the laser is emitted, the laser symbol appears and the reading is 9 mA. However, when it is not emitting, there is no laser symbol, but it will leave a trace and the ammeter reading 8 mA. When I frame the incision, the LCD reads 1 mA, and there are faint burn marks.
2.Analysis:Unplug the signal terminal, press the power test, observe the phenomenon of the ammeter, to eliminate the power signal interference problem.