We have a Tac32 that the U5 and U7 Chips had visible burn damage. We assumed we had an storm come through. We replaced the board and the car ran fine for 4 weeks and same thing again. There has not been any fuse replacements performed since the install. I guess it could be two electrical storms, but doubtful. Any ideas or suggestions?

Well I don’t have board prints but, they are both 16 Port I/O controllers. U7 runs the spare I/O ports Con 36 & 37 (ports 13 & 12 respectively.) U5 controls Con 39 (Port 10) fire service, EPNP. Static & Dynamic sensors on Con 14, Teach 1 for front HN riser, Teach 2 for rear riser, FSSR & STBC inputs on Con 35 (never seen used) & spare I/O on Con 32 pins 1 & 2 (Port 14 I/O 1 & 2.)
All they have in common is power, it gets P24 through F_P24 from the power supply and 3.3v but that’s generated on the board. And SPI communication with the micro controller U4, also on the IOC.
I think I’d replace the power supply but curious if any of the spare I/O are used on Con 36 & 37.

Put a Battery operated UPS on to elimate incoming power like Thyssen does on Tac20 & 22. May be able to sell to customer.

Cons 36 and 37 are not used. Thanks for taking the time to look at that. It does appear that the spots on the chips are burned on the 24 volt side In addition to that, as I was following the traces this morning I also found the U8 chip burned visibly and U 6 had started getting hot.

The UPS is a good idea since it has surge protection.

Update on this one....Access electronics was able to replace the driver chips since those are readily available. They were not able to verify operation but sent it back to us with that in mind. We replaced the power supply and added surge protection. Did not have to do SP and NP learns. Right now it is running. If it goes down again, I will post.