Testing the switch matrix inputs with the test EPROM

Steps

• Set DIP switches 1 to 8 off.
• Find the RC filter networks above the DIP switches, R12-R19 with C16-C23.
• Short C16 with a clip lead: PB0 on U4 should pulse. C17 gives PB1, C18 PB2 and so on.
• A line that does not respond points at its input buffer: PA0 to PA3 come from Z13 pins 11, 8, 3 and 6; PA4 to PA7 from Z14 pins 11, 8, 3 and 6.
• Output lines run through Z12 (PB0 pin 1, PB1 pin 3) and Z11 (PB2 pin 13, PB3 pin 11, PB4 pin 5, PB5 pin 3, PB6 pin 1, PB7 pin 9).

Systems

• Gottlieb System 80
• Gottlieb System 80A
• Gottlieb System 80B

Related tips

• System 80 switch matrix diodes
• Game won't start or boot because the slam circuit is open
• All displays flash "000000" at power-on: open slam circuit
• Permanently close the slam circuit on the CPU board
• Test EPROM stalls at the switch matrix RIOT (U4)
• Haunted House switch matrix wiring
• CPU board connector A1J6 (playfield switch matrix)
• How the switch matrix is scanned

Source: Gottlieb System 80 Test EPROM V3.2 (February 2015), Pinitech