Lincoln Electric SP-250 Welding System User Manual


 
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F-21
TROUBLESHOOTING & REPAIR
F-21
IDEALARC SP-250
NOTE: DO NOT DISASSEMBLE THE
SCR RECTIFIER HEAT SINK ASSEM-
BLY.
6. Test for high or infinite resistance
from the anode to the cathode of
SCR 1. See Figure F.4. Use an
analog ohmmeter (Multimeter).
FIGURE F.4 - SCR 1 Test Points.
7. Test for high or infinite resistance
from the cathode to the anode of
SCR 1 by reversing the meter leads.
See Figure F.4.
a. If a high or infinite resistance is
indicated for both tests 6 and 7,
the SCR 1 is not “shorted”.
b. If a low resistance is indicated in
either tests 6 or 7, the SCR is
faulty. Replace SCR Assembly.
8. Repeat Steps #7 to test SCR 2.
9. Reconnect leads X2 and X3.
10. Reconnect Plugs J3 and J6.
11. If this test did not identify the prob-
lem or to further test the SCR, go to
the Active SCR Test.
STATIC SCR RECTIFIER ASSEMBLY TEST