Fault Finding Tests - Thermal Dynamics C-70A CUTSKILL Service Manual

6.05 Fault Finding Tests

A. Diode Testing Basics
Disconnect primary power at the source before disassembling the power supply, torch, or torch leads.
Testing of diode modules requires a digital volt/ohmmeter that has a diode test scale. Remember that even if the
diode module checks good, it may still be bad. If in doubt, replace the diode module.
1. Remove AC power. Refer to Appendix 3 Wiring diagram.
2. Locate the IGBT diode module to be tested.
3. Remove P5 from IGBT module.
4. Set digital volt/ohmmeter to diode test scale.
5. Connect the volt/ohmmeter positive lead to the anode (+) of the diode and the negative lead to the cathode (-) of the
diode for forward bias testing (refer to following figure). A properly functioning diode will conduct in the forward
bias direction and indicate between 0.3 to 0.9 volts.
TROUBLE SHOOTING
WARNING
Forward Bias
Diode Conducting
Diode Test Symbol
Anode
Cathode
Testing Diode Forward Bias
6-6
Art # A-00307
0.75
VR COM A
_
+
Manual 0-4699