Reflowing surface-mount chips on the switch matrix board

Steps

• Take the switch matrix board out and work on it at the bench.
• Flood one row of pins on the leftmost LM339 with solder; bridging the pins together at this stage is fine.
• Lay copper solder wick across the row and heat it to draw off the surplus, leaving each pin freshly soldered.
• Repeat for the other row, then for the four leftmost LM339s and the two leftmost 74LS245 chips.
• Check with a meter on continuity that no neighbouring pins are still bridged before refitting the board.
• If switches still drop out afterwards, replace the board.

Systems

• Capcom

Related tips

• Groups of switches dead or intermittent: loose surface-mount LM339s
• Switch matrix chips on the CPU board
• Optos test good but still don't work: the opto board
• "Check Fuse F114/F115" (F106/F101 on WPC-95): step-by-step
• A dedicated (direct) switch does not work
• Confused switch matrix from LM339s on opto boards
• One switch does not work
• Testing CPU switch rows with the switch levels test

Source: Capcom Pinball Problems/Solutions