Welder User Manual

POWER MIG 255

TROUBLESHOOTING & REPAIR

F-24 F-24

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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.6.

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.

ACTIVE SCR RECTIFIER ASSEMBLY TEST (continued)

FIGURE F.6 — CONTROL BOARD MOLEX PLUG LOCATIONS FOR G3521 PC CONTROL BOARD.