Undeterminable Hardware Error

I have a SLC 500 (503) in a 12 slot rack with an expansion cable to a 4 slot
The I/O is all AC input & output with the exception of a SN Card.
I keep getting an "undetermined hardware error cant determine what slot"
or something to that affect. I have changed both power supply's and still get it
about every couple hours. I re seated all the cards on Saturday and it was good for Monday Tuesday but started again on Wednesday. It is running a conveyor line so they toggle the key to erase fault.
Any thoughts, This line is going to be scrapped in 4 months so I didn't want to
try and upgrade it. It has been in service 24/5 since 1990's

If this has been running since 1990, I would suspect the contacts on the cards. Have you used a pencil eraser to clean the contacts on the cards? Overtime those contacts can get a film buildup and cause intermittent contact. So using an eraser, not the one at end of a pencil but the block eraser, scrub the contacts with the eraser. Maybe the contacts are just dirty.

Bad solder joints on the backplane give the same problem, after years of working the solder becomes brittle & cracks round the pins.
If cleaning does not cure it try re-soldering the connections usually a hot iron & a little multicore solder may be required to eat the corrosion so it flows.

I will try cleaning the contacts where the card seats, As I said I just pulled them out and re seated them and it was good for a few days. I will have to remove the terminal blocks to get the cards all the way out something I didn't do last time. If that doesn't do it I will look at replacing the racks A13 & A4. thanks

I would also think backplane or connections between card(s) and backplane. I doubt the connections between the field wiring arm and the cards is at play, which I believe, on a SLC system, are the only circuit board contacts you could clean with an eraser.

One other potential culprit would be 1746-OW16 cards (if you have any). I have a really old thread where I chased down a ghost due to a failing inductive load on one of these cards, but if you made things better by reseating cards, then you probably do have a backplane or a card problem that is intermittent.

All cards, except SN, are IA16 & OA16, I guess that leaves me with a backplane issue.
Looks like I will be swapping out items until the fault goes away. I was thinking of uncoupling and re connecting the expansion cable, any chance that might be the culprit?

If you have a spare backplane, I would change that out as a next step. It can look time consuming, but it is usually not all that hard to do if you remove the wiring arms from the cards and let them hang, pull the whole populated chassis out, stick the new one in place, ensure that the bottom left screw is well grounded, then transfer the cards to the new rack, screw in all the wiring arms and you are back in business relatively quickly.

The last time I swapped a 13 slot backplane that was fully loaded it took less than an hour. We did this after the customer had played musical cards for several weeks and still hadn't gotten anywhere...same fault as yours by the way.

Thanks , Looks like I know what I'm doing Saturday

roxusa said:

All cards, except SN, are IA16 & OA16, I guess that leaves me with a backplane issue.
Looks like I will be swapping out items until the fault goes away. I was thinking of uncoupling and re connecting the expansion cable, any chance that might be the culprit?

Click to expand...

It is possible. That was my first thought as to the cause of your problem.

OG

Quick update I changed out the 13 slot rack and have not had an error in 2 weeks.
I did have to unplug one end of the expansion cable to accomplish this but
I believe the backplane was my issue. Time will tell. hope this thread poins someone else in the right direction. Thanks

Now you got it working, plan for an upgrade to something more modern before it slips from everybodys' mind.