Removing a soldered transistor, bridge or chip without lifting pads

Steps

• Clip the failed part off the board, leaving its leads as long as you can.
• Heat each remaining lead on its own and pull it out with needle-nose pliers.
• Clear the leftover solder from the holes with a desoldering tool.
• Use as little heat as possible: too much lifts or cracks traces, too little rips out the plated-through holes.
• When a chip is replaced, fit a good machine-pin socket rather than soldering the chip in.

Systems

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

Related tips

• Replacing a driver board bridge rectifier without tearing traces
• Driver transistor dies after fitting a coil that has a diode
• Testing loose transistors on the bench
• Testing a bridge rectifier out of circuit
• Mount replacement bridges raised off the board
• Bridge rectifiers to use on WPC-S and earlier driver boards
• 20-second test for shorted coil driver transistors
• Replace the pre-driver along with a failed driver transistor

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