Kemppi Mastertig MLS 3003 ACDC Service Manual page 23

Measurements
Z004 Pre-inverter, IGBT:
- Power should be off !
- With these measurements you can find short circuits and partly open circuits that indicates fault in
the machine.
- Measure diodes in forward and reverse direction. Forward diode threshold voltage is ~0,4 V, reverse
direction infinite.
- Measuring points have been marked in the picture below. Four (4) measurements must be
conducted to be sure of correct operation of Z004.
12
14
17
10
.
Diode 1
.
Diode 3
22
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Diode 1.
1.
8
6
3.
4
Diode 3.
Diodes* Measuring points
2
1. 8 -> 12
2. 2 -> 22
3. 4 -> 14
4. 4 -> 17
* Diodes marked with red color in the right hand picture.
2.
4.
Value
~ 0,4 V
~ 0,4 V
~ 0,4 V
~ 0,4 V
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