122 Powermax125 Service Manual 808070
8 – Troubleshooting and System Tests
IGBT device test using a non-Hypertherm tester
The device tester shown in Figure 10 on page 123 has 1 LED and 1 push-button switch that are used in combination to
perform 2 tests.
Before an IGBT can be tested, it must be electrically isolated from all circuits. If the IGBT
is installed in a power supply, remove the power board and any lead connections before
testing.
1. Inspect the IGBT for cracks or black marks. If it is damaged, replace the IGBT.
2. Verify that the 9 V battery reads greater than 8.0 V.
3. Connect the test leads as shown in Figure 10.
4. With the test leads connected and without pressing the push-button switch, the LED should not illuminate. If the LED
is illuminated, then the IGBT is shorted. Replace the IGBT.
5. With the test leads connected, press the push-button switch. This time, the LED should illuminate. If the LED does
not illuminate, then the IGBT is open. Replace the IGBT.
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