Troubleshooting & repair, Snubber resistors test (continued) – Lincoln Electric INVERTEC SVM129-B User Manual

Page 77

TROUBLESHOOTING & REPAIR

F-39

INVERTEC® STT® & STT® II

SNUBBER RESISTORS TEST (continued)

FIGURE F.13 - SWITCH BOARD TEST POINTS

6. Test for 25 ohms resistance from lead termi-

nal 401 to terminal 12 on the switch board.
See Figure F.13.

a. If 25 ohms is measured, resistor R4 is OK.

b. If 30 ohms or more is measured, resistor

R4 is faulty and must be replaced.

c. If 20 ohms or less is measured, resistor

R4 is faulty and must be replaced.

7. Repeat the same procedures to test R5, R6,

and R7 according to Table F.6.

8. Reconnect leads 401/403 and 402/404 to the

switch board.

9. Install the case wraparound cover.

L8441

SWITCH

401

401/403

402/404

Check

Test Result

Conclusion

Next Test Step

Repair Action

Lead 401 to

25 ohms

Continue

Terminal 12

>30 ohms

R4 open

Replace R4

<20 ohms

R4 faulty

Lead 402 to

25 ohms

Continue

Terminal 9

>30 ohms

R5 open

Replace R5

<20 ohms

R5 faulty

Lead 403 to

25 ohms

Continue

Terminal 12

>30 ohms

R6 open

Replace R6

<20 ohms

R6 faulty

Lead 404 to

25 ohms

Continue

Terminal 9

>30 ohms

R7 open

Replace R7

<20 ohms

R7 faulty

> = GREATER THAN < = LESS THAN

TABLE F.6 – SNUBBER RESISTORS TEST