Bally 6000's 77 Error

[mwade109]

Greetings,  I have two Bally 6000's with the wheel feature and needed to replace the batteries in them.  Both were working perfectly everyday before the change.  Now, I get a random 77 error, could be when it's first turned on, could be in the middle of play.  Usually open/close the main door clears it, temporarily.  I have tried ramclear with 3 different sets of ram clear chips I have, holding psuedo & test till getting the "CH C followed by CL C" , putting back in the game chips, exiting out of time set, hitting test 11 times till I see 27 in the window, changing option 51 to 2000, 56 to 0 and 58 to 2000 then closing the door and seeing what happens.  I could see if one machine has a problem but both of them never had this problem before changing the battery and ramclear.  Any ideas?

[Sunrise Side]

77 is secondary device comm. Failure. Top unit spinning wheel possibly . Check cable connection on front of MPU. The cable that has to be disconnected before removing MPU tray.