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TROUBLESHOOTING & REPAIR | ||
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FIRING BOARD TEST
FIGURE F.7 - Terminal Strip Jumper Wire Connections
10.Rotate the output control poten- tiometer (R1). As the potentiometer is turned clockwise, the LEDs should glow brighter. As the poten- tiometer is turned
a.If the LEDs glow and change in brightness equal- ly as the potentiometer is turned and the problem continues, then the SCR bridge may be faulty. Perform the SCR Bridge Test.
b.If any or all of LEDs 1 through 6 do not glow, or do not change in brightness equally as the potentiome- ter is turned, continue to next step.
c.If one or two LEDs stay bright or dim while the oth- ers change, this could indi- cate either an open or shorted gate or a faulty snubber on the related SCR assembly. Perform SCR Bridge Test.
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 poten- tiometer (R1) is rotated, the DC voltage between leads #231 and #215 should vary from 6 to 15 VDC.
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 potentiometer (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 voltage between leads #231 and #215 should NOT vary and should remain at a constant approx- imate 5.8 VDC.
NOTE: The DC voltage may vary slightly at the lower portion of the range.