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F-66

F-66

TROUBLESHOOTING & REPAIR

FIELD EFFECT TRANSISTOR/SWITCH BOARD TEST (continued)

TABLE F.2 – SWITCH BOARD 1 RESISTANCE TEST TABLE (Continued)

Apply

Apply

 

 

 

 

Positive

Negative

 

 

 

 

Test

Test

 

 

 

 

Probe to

Probe to

Test

 

Repair

Next

Terminal

Terminal

Result

Conclusion

Action

Procedure

 

 

 

 

 

 

12A

1T

Less than

OK

None

Continue

 

 

100 ohms

 

 

 

 

 

Greater

Open

Replace 4

Snubber

 

 

than 1K

 

Switch

Resistor

 

 

ohm

 

Boards

Test

 

 

 

 

 

 

1T

12A

Greater

OK

None

Continue

 

 

than 1K

 

 

 

 

 

ohm

 

 

 

 

 

Less than

Shorted

Replace 4

Snubber

 

 

100 ohms

 

Switch

Resistor

 

 

 

 

Boards

Test

 

 

 

 

 

 

12A

401

Greater

OK

None

Continue

 

 

than 1K

 

 

 

 

 

ohm

 

 

 

 

 

Less than

Shorted

Replace 4

Snubber

 

 

100 ohms

 

Switch

Resistor

 

 

 

 

Boards

Test

 

 

 

 

 

 

401

12A

Less than

OK

None

Continue

 

 

100 ohms

 

 

 

 

 

Greater

Open

Replace 4

Snubber

 

 

than 1K

 

Switch

Resistor

 

 

ohm

 

Boards

Test

 

 

 

 

 

 

9A

402

Less than

OK

None

Continue

 

 

100 ohms

 

 

 

 

 

Greater

Open

Replace 4

Snubber

 

 

than 1K

 

Switch

Resistor

 

 

ohm

 

Boards

Test

 

 

 

 

 

 

402

9A

Greater

OK

None

Continue

 

 

than 1K

 

 

 

 

 

ohm

 

 

 

 

 

Less than

Shorted

Replace 4

Snubber

 

 

100 ohms

 

Switch

Resistor

 

 

 

 

boards

Test

 

 

 

 

 

 

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).

POWER WAVE 450

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Image 126
Lincoln Electric SVM112-B service manual Troubleshooting & Repair