Have several GAL IV controllers giving intermittent DON IO failed off fault. This is a hospital complex and today two people were trapped. I have replaced MC, ME & the U31 chip. According to GAL tech support all that is left to cause issue is the Quattro drive board which has the RLY1 & RLY2 on the board and costs $4500. Just wondering if anyone else has come across this and what have you done to fix it?
See attached photo.