Lincoln Electric IDEALARC CV-300 Service Manual page 55

F-16
STATIC OUTPUT RECTIFIER BRIDGE TEST (CONTINUED)
6. Disconnect the D4 diode pigtail
from the positive strap. See Figure
F.7.
FIGURE F.7 - Procedure to discon-
nect the D4 diode pigtail from the
positive strap.
7. Remove the red insulating paint
from the heat sink test points. See
Figure F.8.
TROUBLESHOOTING & REPAIR
IDEALARC CV-300
FIGURE F.8 - Heat sink test points.
NOTE: DO NOT DISASSEMBLE THE
HEAT SINKS.
8. Test SCR1 for proper resistance.
Resistance should be high or infi-
nite.
a. Measure the resistance from
the anode to cathode of SCR1
using an analog volt-ohm meter
(Multi meter) set at R X 1000
ANODE
CATHODE
scale. See Figure F.9.
FIGURE F.9 - SCR test points.
b. Reverse the meter leads and
measure the resistance from the
cathode to anode of SCR1.
See Figure F.9.
c. If a low resistance is measured
for either test a or b, SCR1 is
faulty. Replace the SCR
assembly.
9. Test the resistance of SCR2 and
SCR3 using the same procedure
F-16