Bussed and isolated resistor networks
A network with an odd pin count (such as 9 pins, "560 x 8") is bussed: all resistors share a common pin, marked by a white square on the board, and these are labelled RA. An even pin count (such as 8 pins, "1K x 4") is isolated: each resistor has its own pair of pins, labelled RB.
Systems
Related tips
- Test a resistor network with a meter
- Make a bussed network from single resistors
- Pressing one switch closes the whole row: bad 4011 chip on the CPU board
- Which switches are outside the switch matrix
- Switch column (drive) circuit on the CPU board
- Switch row (return) circuit on the CPU board
- Whole switch column dead after working under the playfield
- Coin door test buttons bypass the switch matrix
Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Three, Clay Harrell (pinrepair.com)