Lincoln Electric LF-72/74 Service Manual page 96

F-12
TROUBLESHOOTING AND REPAIR
41
TEST PROCEDURE
1. Remove the input power from the
unit.
2. Using a 5/16 nut driver remove the 5
screws holding the cover.
3. Apply the correct input voltage
(42VAC) to the LF72/LF74 unit.
DIODE BRIDGE TEST
(continued)
FIGURE F.4 – CONTACTOR
-
580
LF-72/74
+
42
4. Check for the correct input voltage at
leads 41 and 42 on the bridge.
the input voltage is not there check
the wiring back to the receptacle
assembly pins I and K.
5. Check for the proper output on leads
580 negative and 522 positive.
voltage should be 59VDC.
only reading 38VDC the control circuit
is open. Check the wiring and the
connections back to your control
board.
F-12
552B
552A
If
The
If you are