Lincoln Electric IDEALARC DC-600 Service Manual page 72

F-28
9. Locate LEDs 1 to 6. Each LED should glow
with equal brightness.
NOTE: LEDs 1 to 6 indicate that the gate firing
signals are being generated to send to each of
the SCRs.
10. Set the OUTPUT CONTROL SWITCH (SW3)
in the "Output Control at DC-600" position.
11. Set the WELDING CONTROL SWITCH in
either of the "CV" positions.
12. Rotate the OUTPUT CONTROL POTEN-
TIOMETER. As the pot is turned clockwise,
the LEDs glow brighter. As the pot is turned
counter-clockwise, the LEDs dim.
a. If the LEDs glow and change in brightness
equally as the pot is turned and the prob-
lem continues, then the SCR Bridge may
be faulty. Perform SCR Bridge test.
b. If all of LEDs 1-6 do not glow or do not
change in brightness equally as the pot is
turned, go to Step 13.
c. One or two lights stay bright or dim and the
others change, this could indicate an open
or shorted gate lead or bad snubber board
on related SCR assembly. Perform SCR
Bridge Test.
TROUBLESHOOTING AND REPAIR
FIRING BOARD TEST (continued)
IDEALARC
13. Test for 10 VDC to 13 VDC between leads
#231 and #215 on the Firing Board in CV
mode.
a. Locate on the Firing Board the Molex Plug
with leads #231 and #215 connected to it.
See Figure F.7.
b. Set the ON/OFF PUSH BUTTON to OFF.
c. Remove the Molex Plug from the board.
d. Insert the meter probes into the appropri-
ate Plug lead cavities.
NOTE: OBSERVE POLARITY.
BEING TESTED.
e. Connect the Molex Plug into the Firing
Board.
f. Set the WELDING MODE SWITCH in
either of the "CV" positions.
g. Set the ON/OFF PUSH BUTTON to ON.
h. Rotate the OUTPUT CONTROL POTEN-
TIOMETER clockwise and counter-clock-
wise. The DC voltage between leads #231
and #215 should vary from 10 VDC to 13
VDC as the pot is turned from minimum to
maximum.
i. If the voltage does NOT vary, then the
Control Board may be faulty. Replace.
® DC-600
F-28
DC VOLTAGES