Display board will not light up

Hello, I have a good power distribution board in the instrument and the low voltage power supply is in spec. when measured at the 3 terminals on the left side of the display control board. CPU OK , PWR Fail, and BUF Reset are not lit. Swapped good Eproms into U18 and U19. Does anyone out there have a clue as to what might have caused a failure like this and if so I hope you aren't going to tell me it's the processor as I have no access to a preprogrammed Processor chip. I don't want to throw away a board is it's repairable. Fingers Crossed !!

Equipment: Beckman Avanti J25