Lincoln Electric IDEALARC DC-1000 Service Manual page 57

F-23
FIGURE F.7 – TERMINAL STRIP JUMPER WIRE CONNECTIONS
10. Rotate the output control potentiometer (R1).
As the potentiometer is turned clockwise, the
LEDs should glow brighter. As the potentiome-
ter is turned counter-clockwise, the LEDs
should dim.
a. If the LEDs glow and change in brightness
equally as the potentiometer is turned and
the problem continues, then the SCR
bridge may be faulty. Perform the Static
and Active SCR Tests.
b. If any or all of LEDs 1 through 6 do not
glow, or do not change in brightness equal-
ly as the potentiometer is turned, continue
to next step.
c. If one or two LEDs stay bright or dim while
the others change, this could indicate either
an open or shorted gate or a faulty snubber
on the related SCR assembly. Perform
Static and Active SCR Tests.
11. Locate and test for 6 to 15 VDC between leads
#231 and #215 on the Firing Board in the CV
mode. When the output control potentiometer
(R1) is rotated, the DC voltage between leads
#231 and #215 should vary from 6 to 15 VDC.
TROUBLESHOOTING AND REPAIR
FIRING BOARD TEST (continued)
IDEALARC
12. If an LED continues to be lit and should not be,
a circuit may be faulty on the Firing Board
between a Molex plug and LED. Replace Firing
Board.
13. If the DC voltage does NOT vary, as poten-
tiometer (R1) is rotated, the Control Board may
be faulty.
14. Locate and test for approximately 5.8 VDC
between leads #231 and #215 on the Firing
Board in VV (CC) mode. When the output con-
trol potentiometer (R1) is rotated, the DC volt-
age between leads #231 and #215 should NOT
vary and should remain at a constant approxi-
mate 5.8 VDC.
NOTE: The DC voltage may vary slightly at the
lower portion of the range.
® DC-1000
F-23