SLC 500 losing program after cycling power

I recently had the same problem replaced battery,power filter and processor and then finally the power supply was found to be the cause
 
I will have to check to see if we have another 13 slot rack in use somewhere to swap out to see if the problem follows - I hate to put one that is working in place of the one that was losing its program - what if it is the power and makes the good one go on the fritz.
The ground wire is on the one of the tabs but I dont think it is on the bottom left - I will check that out.
To answer the other question - I can put a breaker in between the filter and the SLC P.S. to shut it off without the Main disconnected.
Thanks Guys. I will keep you informed
 
one more idea...

I have not read all of the other posts but I encountered something with similar symptoms and there is something else that you may want to check.... a couple question first though...

1) Is the program truly lost or will it just not run?
2) Can you see all the remote racks?

The reason that I ask is that I had a situation where there was an odd config that had a controlnet mod in the main rack but an ethernet mod in an aux rack. When power cycled the controlnet config was lost since someone pointed to a location in the controlnet mod that didn't exist for the config fiel... since the ethernet mod was in a remote rack it was not picked up since there were not any comms... just another thing you might want to look into although this is a long shot and the others suggestions seem much more likely.
 
Also what protocol is channel 0? Are ypu using an HMI??
The following are areas of concern if memory corruption occurs for a SLC-5/03, 5/04 or 5/05 processor, for a particular installation:

· Grounding
· Power
· Communications
· I/O
· Controller Spacing and Excessive heat
· Additional Information Related to Channel 0
 
I had same problem. Changed out the power supply today and it fixed the issue. No calls out on power failure anymore. In my case it wasn't a bad ground or 24Vdc power usage or the battery. It was the power supply 1746-P2
 
I realize this is an ancient thread, but I found this site via an internet search ,and this post helped me to fix the same exact problem.

A new Power Supply corrected my issue, and I'm now a member of PLCS.net.
 
I have had this problem before and in most cases was a bad power supply, once it was a bad backplane faulting but that was in a very dirty panel that got everything coated in corn starch dust.
 
Got same issue

After decade , got same issue ,after replaced several batteries ,end up replacing Power module and issue was gone .
 
didn't read all the posts.
we have had this problem on several slc 500 plc processors.
the internal power supply charging the capacitor circuit and getting power from the battery was damaged due to something. we sent them to teamsesco for repair. they came back, checked out, and have not stopped since. Note, teamsesco is a vendor and i am not associated with them.
james
 
On a SLC rack the SECOND thing I replace when this happens is the power supply. And it's every time been a -P2, never had a -P1 or -P4 do this.


However, what I check for FIRST is any analog IO in the rack and replace that.


I have had more problems with SLC analog cards taking the PLC battery down and wiping the program than I have power supplies, and I remember twice having to replace the rack itself.
 
I will add my two thoughts to the conversation. I had a PLC loose it program periodically with a good battery but it was associated with being connected to a 24vdc Power supply. My guess is something on the equipment was shorting or causing an instability in the 24vdc causing the problem. If the plc power supply is a P3 and is 24vdc supplied. Change to a P2, 110vac unit and see if the program drop out stop.
 

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