Cut off the voltmeter input jacks from one end of both voltmeter lead/probes. Strip off approximately 1 inch of the protective rubber covering from the ends where the jacks were removed.
Solder the exposed wire end of the positive lead/probe to one lead of a 220-volt, 6-watt filament lamp. Solder the remaining lead of the lamp to the positive (anode) end of a red 5 mm LED. The lamp acts as a resistor to limit the current going to the LEDs.
Solder the exposed wire end of the negative (black) lead/probe to the negative (cathode) end of the red LED.
Solder the negative (cathode) lead of a 5 mm yellow LED to the positive lead of the 5 mm red LED. Solder the positive (anode) lead of the yellow LED to the negative lead of the red LED. The connection between the two LEDs is a parallel circuit. The parallel circuit allows DC current to flow either through the red or yellow LED depending on the polarity of the circuit. In an AC circuit, current flows in both directions; therefore, both LEDs will light in a parallel circuit.
Turn on a circuit and touch the metal ends of the probes anywhere in the circuit. If the red LED lights, then current is flowing and it is a DC circuit and the polarity of the circuit is aligned with the red diode. If the yellow circuit lights, current is flowing and it is a DC circuit and the polarity of the circuit is aligned with the yellow diode. If the red and yellow diodes are lit, current is flowing and it is an AC circuit. If neither the red or yellow LEDs light, current is not flowing and a bad circuit is indicated. Further probing of the affected circuit will isolate the faulty electronic component in the circuit.