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TROUBLESHOOTING & REPAIR
F-21 F-21
POWER MIG 350MP
CHOPPER BOARD TEST (continued)
FIGURE F.3 – CHOPPER BOARD CONNECTIONS
Table F.1– CHOPPER BOARD RESISTANCE TEST TABLE
TEST PROCEDURE
1. Disconnect the main AC input power to the
machine.
2. Remove the case side panels with a 3/8” nut driver.
3. Locate plug J99. (Later machine do not have J99).
4. Make the following voltage test. From the table
below.
5. Turn the machine off between each test:
a. Carefully insert the meter probes into the back of
each Molex plug cavity.
If 20 VDC is not present check Digital Power Supply.
See the Wiring Diagram.
RESISTANCE TEST
1. Perform the Capacitor Discharge Procedure.
2. Remove input power to the machine.
3. Perform the resistance tests in Table F.1.
300 CHOPPER
C12
+
C1
+
C4
C2
C3
+
+
++
_
_
_
_
C11
C10
C8
C9
B1 B4
B5
B6
B3
B2
B5
B2
B1
B3
B6
B4
J99
FROM
LEAD
TO
LEAD
EXPECTED
VOLTAGE
437+(1J99) 431-(4J99) 20VDC
Test Point
B5(+)
B6(+)
B4(+)
B5(+)
B4(+)
B6(+)
B2(+)
B3(+)
B4(+)
B2(+)
B4(+)
B3(+)
Test Point
B6(-)
B5(-)
B5(-)
B4(-)
B6(-)
B4(-)
B3(-)
B2(-)
B2(-)
B4(-)
B3(-)
B4(-)
Expected Reading
6 K ohms - 9K ohms
6 K ohms - 9K ohms
200 K ohms or Higher
400 K ohms or Higher
200 K ohms or Higher
400 K ohms or Higher
6 K ohms - 9K ohms
6 K ohms - 9K ohms
200 K ohms or Higher
400 K ohms or Higher
200 K ohms or Higher
400 K ohms or Higher