To answer some of your questions.
Chance, The processors were brought back to our office to test in a separate rack to test the same theory. While they were moved around to the different racks at the plant they were installed in, we still felt using a rack/powersupply from a different environment was a good idea. Our test rack performs the same as the racks in the field.
Yes, these controllers have been installed and running every day for about 4 years. The batteries were showing bad which is why we went to replace them.
Yes, we were looking at remanufactured processors. I should have clarified as it caused confusion.
I am aware of the performance difference, however the system that these processors are running does not utilize that communication speed and it can be sacrificed.
I am also aware that series a and B are not currently available new, however we'll be purchasing a used one at a far lower cost than what rockwell charges to repair a bad processor.
I had the same assumption you had yesterday; That these processors were toast. With that known, i repeatedly shorted pins followed by a power up retest over and over and I was able to get one working again. This processor is running and continues to run as we speak regardless of power cycle. Yesterday after i was able to get it to run and communicate a cycle of power would have a 50/50 chance of solid fault or running the test program. This is not the case now, i've been unable to get a solid fault after letting it run all night. I've tried duplicating the issue and am unable to do so after 24 hours of testing. I'll let it run at my bench for another week peridically cycling power before i make a decision as to replace it or not.
Yesterday when I was able to get the processor to communicate and run for a couple hours and then solid fault again after i cycled power, i started thinking that whatever problem these processors share was not caused by replacing the battery. I think that whatever happened it happened prior to the battery replacement and powering it off triggered it. It reminds me of a computer OS who's start up routine is damaged. Sometimes it will come up, sometimes it wont; however, once it is running, it stays running.
The second controller is a different story. I did find out a little more information this morning. I was able to talk with the programmer who originally changed the batteries. While he was on the phone with Rockwell, one of their agents asked him to move the firmware jumper to "PROGRAM" to see if the light pattern changes. Because of this, i think this processor does not have a firmware loaded anymore. This would confirm as to why shorting the pins has no effect. Cant restore default settings for software that doesnt exist. Either way, the firmware upgrade kit is on its way so who knows, maybe it will work.
I just find it odd after all my years working with electronics that 2 units go bad at the same time the exact same way. This wouldnt suprise me if it was a common issue, however Rockwell states there are no known documented cases that match this issue. Thats why I posted here. I wanted to see if others have had this issue and that Rockwell is denying it. It wouldnt be the first time. Control logix L55's