PURPOSE: To enhance working efficiency and reliability, by providing a synthetic tester, a wire feeder and a voltage/current remote control adjusting apparatus.

CONSTITUTION: A wire feeder II is connected to the receptacle 4 of the tester circuit of a synthetic tester I and a voltage/current RC (remote control) adjusting apparatus III is connected to the receptacle 5 of the tester circuit to complete setting. Next, when a remote/local change-over SW (switch) 2 is set to 'local and a local voltage adjusting resistor 6 is rotated to a constant point, a voltmeter 8 oscillators and voltage is applied to a wire feed motor 22 to rotate said motor 22 and the pointer of the ammeter 7 of the tester I also oscillates. The quality of the motor 22 can be determined on the basis of the voltage and current values at this time. Next, when SW2 is changed over to 'remote' and an RC change-over switch SW3 is set to neutral-OFF and the switch SW21 of the feeder II is pushed, the speed of the motor can be freely manipulated by the voltage adjusting resistor 31 of the apparatus III. Further, when the trigger switch SW41 of a welding torch is turned ON, the speed of the motor can be made variable by the operation of the current adjusting resistor 32 of the apparatus III.