Lincoln Electric INVERTEC POWER WAVE 450 SVM112-B Service Manual page 132

F-72
FIELD EFFECT TRANSISTOR/SWITCH BOARD TEST (continued)
TABLE F.5 – SWITCH BOARD 4 RESISTANCE TEST TABLE (Continued)
Apply
Positive
Test
Probe to
Terminal
12D
3B
12D
407
9D
408
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
3B Less than
100 ohms
Greater
than 1K
ohm
12D Greater
than 1K
ohm
Less than
100 ohms
407 Greater
than 1K
ohm
Less than
100 ohms
12D Less than
100 ohms
Greater
than 1K
ohm
408 Less than
100 ohms
Greater
than 1K
ohm
9D Greater
than 1K
ohm
Less than
100 ohms
POWER WAVE 450
Repair
Conclusion Action
OK None
Open Replace 4
Switch
Boards
OK None
Shorted 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-72
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