Lincoln Electric IDEALARC DC-600 Service Manual page 84

F-40
5. Test for high or infinite resistance from the
cathode to the anode of SCR 1 by reversing
the leads. See Figure F.14.
a. If a high or infinite resistance is indicated
for both tests 4 and 5, the SCR 1 is not
shorted.
b. If a low resistance is indicated in either
strips 4 or 5, go to Step 6.
6. Disconnect the snubber circuit. See wiring dia-
gram.
TROUBLESHOOTING AND REPAIR
STATIC SCR TEST (continued)
FIGURE F.14 - SCR 1 Test Points
IDEALARC
7. Retest SCR 1 with the snubber circuit discon-
nected.
a. If a low resistance is still indicated, SCR 1
is faulty. Replace. If one SCR is shorted
they may all appear shorted. The SCRs
will have to be tested separately by dis-
connecting the secondary leads from the
bridge assembly.
b. If a very high or infinite resistance is indi-
cated with the snubber circuit disconnect-
ed, replace the snubber circuit.
8. Repeat Steps 3 to 7 for SCRs
2 - 6.
9. Replace all Molex Plugs on the Firing Board
and Control Board.
NOTE: To further check the SCR's Function, use
an SCR tester and proceed to active SCR
Test.
® DC-600
F-40