Lincoln Electric RANGER 305 D Service Manual page 116

RANGER 305D
OUTPUT RECTIFIER BRIDGE TEST (continued)
7. Check for grounds by placing one of the ohm meter
probes on a clean, unpainted metal surface of the
machine. Touch the other probe to each of the five
rectifier terminals. The resistance 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 a test
equipment used.
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 rectifier.
POS.
W3
W2
W1
W4,W5
W10
FIGURE F.16 – SHUNT/RECTIFIER LE DS
NEG.
W6,W11
FROM SHUNT
Test all of the diode groups per the Table F.1.
10.
TOP
W1
CENTER
W2
W3
BOTTOM
OR
F 59
TROUBLESHOOTING & REPAIR
OUTPUT
RECTIFIER
BRIDGE
CHOKE