Hello Again,
I recently replaced the original 941 CPU in a S5 / 155 from 1994 with a refurbished 941 from Classic Automation.
It installed and powerup fine, did an overall reset to read program from EPROM and everything seemed to work fine. Cycled the machine several times, all looked good. It was the end of the day, so I powered the machine down and the next day on power up it had not retained the program (fast red LED and steady red BASP).
The machine operator tells me he did many overall resets but still red and no outputs, then eventually an overall reset took. He prepared for a long days run when another photo sensor failed. After managing sensor, we are back to startup having to make an overall reset to load the program from eprom. I’m convinced the battery is dead at this point, but now the overall resets only result in a slow flashing red stop led and steady red basp.
I suspect the stop is coming from a programmed response to some condition that’s being met. But can it be the eprom?…I think it is the original …30 years old. I’ll have a new battery tomorrow, but I don’t think that’s going to fix this problem
My crude understanding of the eeprom - ram - battery combination is you don’t need a battery to load a program into ram from the eprom , the battery is there to maintain the program in ram for convenience.
Can the eprom finally reach an end life if its only ever been used for reading?
I really appreciate all that I’ve learned from you guys.