Lincoln Electric VANTAGE 400 Service Manual page 107

F-59
OUTPUT RECTIFIER BRIDGE TEST (CONTINUED)
7. Check for grounds by placing one of the ohm
meter probes on a clean, unpainted metal sur-
face of the machine. Touch the other probe to
each of the five rectifier terminals. The resis-
tance to chassis ground from each terminal
should be very high, 500,000 (500K) ohms
minimum. If the resistance reading is less than
specified, the rectifier is grounded and should
be replaced.
8. If using diode checker or a multimeter with
diode check functionality, read and understand
the instructions that accompany your test
equipment.
9. If using an analog ohmmeter, the forward bias
test will indicate low resistance and the reverse
bias test will indicate high resistance. Precise
ohm values for this test will vary depending on
the test equipment used.
TROUBLESHOOTING & REPAIR
FIGURE F.15 - SHUNT/RECTIFIER LEADS
W1
W2
W3
OR
VANTAGE® 400
NOTE: A digital Ohmmeter is not recommended for
this test. A typical digital Ohmmeter does
not provide enough voltage or current flow
to reliably test the diodes used in this recti-
fier.
10. Test all of the diode groups per the Table F.1.
TOP OUTPUT
RECTIFIER
CENTER
BRIDGE
BOTTOM
CHOPPER BOARD
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