"Mains saferam signature corrupted" It's clearly not the battery, but it is.

[kcirrick]

I have two machines.  A slant top and an upright.  Both were working fine, but after sitting unused for months the upright got the dreaded "Mains saferam signature corrupted".  I figured it was a battery issue, but I was focused on a completely different project and so didn’t bother with it.  (I was building a Pirates of the Caribbean pup-pack for a visual pinball table.)  I finally got around to swapping in a new battery, but to my dismay I got the same error.  I have two MPU boards for each machine so I just swapped in the extra board.  "Mains saferam signature corrupted"  I swapped in a new battery on this board and got the same error.  I then took the spare board from the slant top and put it into the upright which involved removing it from it’s tray and putting it in the upright’s tray.  "Mains saferam signature corrupted"  I then took the board that I knew was working out of the slant top and put that into the upright "Mains saferam signature corrupted"  What the hell!?  All the while I’m swapping batteries around and checking voltages on the batteries verifying 3.6v with my meter. It was getting late and I was done for the night so I took that “working” board and put it back into the slant top.  "Mains saferam signature corrupted"  I decided I wasn’t done and tried all four boards in the slant top.  Now, all four boards got the same error in both machines.  I double checked 3.6v in the batteries and it was good.  I was thoroughly stumped.  This is clearly a battery issue, but it’s clearly not.

Even though the batteries showed good voltage I went ahead and ordered new ones.  When they showed up I was able to reconfigure all four boards with no problem.  (Replacing the batteries was easy because the first time I did it I unsoldered old batteries from the boards and installed AA battery holders.)  Part of the problem was that I had some unused “new” batteries, but then realized I had purchased them four years ago.  Purchasing brand new fresh batteries solved the problem.

So, if you’re getting this "Mains saferam signature corrupted" error even though your batteries show the proper 3.6v go ahead and try swapping in brand new batteries anyway.  It might save you from going through the frustrations I went through.

[shortrackskater]

I think the problem is that testing with a multi meter shows voltage without a LOAD in the circuit.
I'm guessing (someone chime in please) maybe putting a 100 ohm in parallel with the battery, and then watch the voltage and see if it drops. 

[kcirrick]

Not a bad idea. I've trashed all the old batteries, but I think I know where I can find one.  I'm going to reconfigure the upright anyway because I installed Cash Encounters.  Not a bad game, but I'd rather have my choice of ten games.  I'll find that old battery and test it while on the board and powered up.