Control board power-on checks

Steps

• Power-on reset happens when +5 V is applied; watch the reset signal at test connector TC1 pin 17: it should go high a short time after the 5 V comes up.
• Measure +5 V DC within 5% (4.75 to 5.25 V) at TC1 pin 7.
• Measure 3.9 to 4.1 V DC at the plus side of the memory battery.
• At Z3 pin 6 look for a 5 V peak-to-peak square wave with a period of about 0.28 microseconds (the crystal output).
• Check the system clock at TC1 pin 15 and the read/write line at TC1 pin 11.
• Do these checks before any of the dynamic signal checks.

Systems

• Gottlieb System 80
• Gottlieb System 80A

Related tips

• System 80 control board chips
• Control board clock frequency
• Control board A1-J1 power connector
• Buffer chips protect the control board LSI parts
• The battery-backed 5101 RAM uses only data lines DB0 to DB3
• Test connector TC1 pins for the address and data bus
• How the 32 option switches are read
• Key pins on the System 80 LSI chips

Source: System 80 Service Manual, Gottlieb