Bally 5500 Credit Button

[pinshoppe]

I have a Bally 5500 and the previous owner has modified it in some way where the change button adds credits.  When I put it in input test, the change button activates the coin out switch.  I do not see any obvious modifications.  Has anyone encountered this before?    Thanks in advance.


U12-ME950000-1-1(FA00)
U15-ME950000-1-0(0306)
U3-FR-ME950000-1-3(5901)
U4-SE950000-1-2(42A7)
U18-smi7343
U20-7343

[Badbaud]

Follow the wires, there is a tiny little circuit board with a tiny computer chip that mimics the coin in pulse that the coin optic board would normally produce when a coin is accepted.

[pinshoppe]

I have traced the wires and they go straight to the backplane board.  I have unwound the bundle and there are no modifications in there either. When i have the slot in input test, the white button on the optic board registers switch number 42 i believe. Is it possible there is a jumper on the backside of the backplane board that ties the coin optics with the change button? If so, i figure it would go into a tilt since no coin was sensed in the comparitor.  Also i thought the white coin button only worked with the door open.