Dc Tig Machines, Calibration Of The Arc Voltage Feedback - ESAB Arc 4000i Service Manual

DC TIG machines, calibration of the arc voltage feedback

The arc voltage input can be calibrated using trimming potentiometer R87 on circuit board
20AP1. The board has been calibrated in the factory: further adjustment should not
normally be necessary.
Use an accurately calibrated external voltmeter to measure the voltage at the welding
current terminals.
TIG machines
Disconnect the power supply to the HF starting function by removing fuse 2FU5 from
transformer 2TC2: see the circuit diagram on Page 18. Set the power source to the MMA
welding mode.
TIG and MMA machines
1. Set a welding current of about 100 A, supplying it to a resistive load so that the voltage
is 25 -- 30 V. Using an external voltmeter, measure the voltage across the welding
current terminals.
2. Using the potentiometer, adjust the value shown on the display so that the voltage
shown is about 0.2 -- 1.6 V lower than the voltage at the welding current terminals. This
difference between the measured and the displayed voltages compensates for the
voltage drop in the welding current cables.
Position of potentiometer R87 on circuit board 20AP1
cu19f3calarcv
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S0740 800 191/E080229/P78