Lincoln Electric POWER WAVE C300 Service Manual page 89

F-70
OUTPUT RECTIFIER TEST PROCEDURE (continued)
B51
B39
B38
PROCEDURE
1. Disconnect the input power to the POWER
WAVE® C300 machine.
2. To gain access to the Output Rectifier test
points first perform the Case Cover and DC
Link Capacitor Discharge Procedure.
3. Locate test points B51, B38 and B39. See
Figure F24.
4. Using the ohmmeter check the resistances
from B51 to B38/ B39. Polarity of the ohmme-
ter is important. With the positive meter probe
on B51 and the negative meter probe on
B38/B39 the resistance reading should be very
high. With the positive meter probe on
B38/B39 and the negative probe on B51 the
resistance reading should be very low. Thus a
forward diode drop. If the meter readings indi-
cate a very low resistance is both directions
the output rectifier may be shorted.
meter readings indicate a very high resistance
in both directions the output rectifier may be
TROUBLESHOOTING AND REPAIR
FIGURE F.24 – TEST POINTS
If the
POWER WAVE® C300
open.
5. If the Output Rectifier is faulty the entire Switch
Board must be replaced.
6. Replace the case covers.
F-70