How the WPC lamp matrix works

Computer-controlled lamps (not GI) sit in an 8 by 8 matrix, 64 lamps. TIP107s switch +18 V DC onto the columns and TIP102s switch the rows to ground; the strobing gives the bulbs an effective 6 V or so. Because the TIP107s source current, column drivers fail more often than row drivers.

Systems

• WPC Alpha-Numeric
• WPC Dot Matrix
• WPC Fliptronics
• WPC DCS
• WPC-Security (WPC-S)
• WPC-95

Related tips

• How the WPC lamp matrix is switched
• WPC lamp matrix and GI driver parts
• A lamp column or row stays on all the time
• A row or column of lamps stuck on and too bright
• Which transistor drives which WPC solenoid and lamp circuits
• BR1 (D11-D14 on WPC-95) and the board around it scorched
• A lamp row very bright or dead
• Where the WPC coil and lamp drivers sit

Source: Repairing Williams/Bally WPC Pinball Games from 1990 to 1999, Part Two, Clay Harrell (pinrepair.com)