Troubleshooting & repair – Lincoln Electric POWER MIG 255 SVM144-B User Manual

Page 58

POWER MIG 255

TROUBLESHOOTING & REPAIR

F-20

Retur

4. Verify that the capacitors have

completely discharged with a volt-
ohmmeter.

5. Disconnect plugs J6 from the G3521

control board and J9 from the M19248
snubber PC board. This electrically
isolates the SCR bridge assembly.
See Figure F.3.

TEST PROCEDURE

1. Disconnect main AC input power to the

machine.

2. Remove the case top and side panels

with a 3/8 in. nutdriver.

3. Remove the tool tray with a 5/16 in. nut-

driver.

STATIC SCR RECTIFIER ASSEMBLY TEST (continued)

FIGURE F.3 — REMOVE PLUGS J6 AND J9 TO PERFORM STATIC RECTIFIER ASSEMBLY TEST.