Lincoln Electric INVERTEC POWER WAVE 450 SVM112-B Service Manual page 129

F-69
FIELD EFFECT TRANSISTOR/SWITCH BOARD TEST (continued)
TABLE F.4 – SWITCH BOARD 3 RESISTANCE TEST TABLE
Apply
Positive
Test
Probe to
Terminal
4T
12C
9C
3T
4T
9C
NOTE: K ohm = ohm reading multiplied by 1000.
NOTE: Always make sure that all four Switch Boards are changed at the same time. Never mix
an old style (different part number) Switch Board with a new style (new part
number).
TROUBLESHOOTING & REPAIR
Apply
Negative
Test
Probe to Test
Terminal Result
12C Greater
than 1K
ohm
Less than
100 ohms
4T Less than
100 ohms
Greater
than 1K
ohm
3T Greater
than 1K
ohm
Less than
100 ohms
9C Less than
100 ohms
Greater
than 1K
ohm
9C Less than
100 ohms
Greater
than 1K
ohm
4T Greater
than 1K
ohm
Less than
100 ohms
POWER WAVE 450
Repair
Conclusion Action
OK None
Replace 4
Shorted Switch
Boards
OK None
Open Replace 4
Switch
Boards
OK None
Shorted Replace 4
Switch
Boards
OK None
Open Replace 4
Switch
Boards
OK None
Open Replace 4
Switch
Boards
OK None
Shorted Replace 4
Switch
boards
F-69
Next
Procedure
Continue
Snubber
Resistor
Test
Continue
Snubber
Resistor
Test
Continue
Snubber
Resistor
Test
Continue
Snubber
Resistor
Test
Continue
Snubber
Resistor
Test
Continue
Snubber
Resistor
Test