Lincoln Electric RANGER SVM148-B Service Manual page 83

F-24
OUTPUT RECTIFIER BRIDGE TEST (continued)
FIGURE F.2 – LOCATION OF OUTPUT RECTIFIER DIODE LEADS
TEST PROCEDURE
1. Conduct this test with the engine off.
2. Using the 3/8" wrench, remove the sheet
metal screws from the right and left front
case sides.
3. Carefully remove the right and left front
case sides.
4. Locate the two halves of the output rectifi-
er. The negative plate is located on the
lower left side of the machine behind the
case front. The positive plate is located on
the lower right side of the machine behind
the case front. See Figure F.2.
5. Using the 1/2" wrench, remove the nuts and
washers holding the diode pigtails and the
heavy current-carrying leads to the studs
on the rectifier plates. Note leads and pig-
tail placement for reassembly.
TROUBLESHOOTING & REPAIR
Left side (–)
RANGER 300 D AND 300 DLX
Right side (+)
6. Electrically isolate the diode pigtail leads
by carefully bending them out into "free
air."
7. With an ohmmeter or diode tester, check
each of the four diodes from their pigtails
to their respective heat sinks.
8. Reverse the tester leads and check the
diodes again. Diodes should have a low
resistance in one polarity and a very high
resistance in the opposite polarity.
9. Replace any "shorted" or "open" diode as
the tests indicate.
Removal and Replacement Procedure.
10. Replace the pigtails and heavy leads onto
the correct studs. Assemble the washers
and nuts.
11. Replace the left and right front case sides.
F-24
See the Diode