- Short out G1 to E1 and G2 to E2. With a multimeter set to check diodes, check across the C1-C2E1 junction. With the (+) probe on C1 and the (-) probe on C2E1, you should see an open circuit. Switch the probes. You should see a diode drop on the meter.
- Check across the C2E1-E2 junction. With the (+) probe on C2E1 and the (-) probe on E2, you should see an open circuit. Switch the probes. You should see a diode drop on the meter.
- With a 9 volt* battery, connect the (+) terminal to G1 and the (-) terminal to E1. Using your meter (set to check diodes), should see a diode drop across the C1-C2E1 junction in both directions now. Connect the (+) terminal to G2 and the (-) terminal to E2. You should see a diode drop across the C2E1-E2 junction in both directions here as well.
- If the IGBT passed all of the above tests, the IGBT is good.
You may be able to use a second multimeter as a voltage source by setting it to check resistance at its lowest available resistance scale. The (+) probe is the positive side. However, not all meters provide enough DC voltage for this, and may even give you false readings. A known DC voltage from 8 to 15 volts is recommended instead.