How to Test Miller Diodes
- 1). Unplug the Miller welding device to avoid accidental shock. The multimeter provides the electrical current needed for the resistance test.
- 2). Remove the screws from the base of the Miller Welder that hold its cover in place. Detach the cover and set it aside.
- 3). Locate the diodes on the inside wall of the welder where the power cord comes out. Normal diodes look like 5- or 6-inch-long tubes while rectifier diodes are square metal sheets with a terminal on each side.
- 4). Turn on the digital multimeter. Rotate the measurement dial to the resistance setting. On most multimeter devices resistance is denoted by the capital Greek letter omega. Capital omega stands for the ohm, the unit of resistance.
- 5). Connect the black probe of the multimeter to its negative port. Connect the red probe of the multimeter to its positive port. Touch the red probe to the positive lead of the first diode you want to test. Touch the black probe to the negative lead of the first diode you want to test. The resistance should be between 0 and 1 ohm or the diode needs to be replaced.
- 6). Touch the black probe to the positive lead of the first diode tested. Touch the red probe to the negative lead of the first diode tested. The resistance should be infinity or the diode needs to be replaced.
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