[ottoman]

Have a thorough check of all your solder points using a magnifying device and ensure that they are all clean solder connections without any shorts. If they all look good and you still have a problem remove the mod and see if your ps2 still works normally. If so reinstall the chip again taking plenty of time to do a top notch job.

A lot of problems can come from using poor wire that isn't good enough for the job. Alweays use kynar insulated awg 30 wire for signal connections and the largest multicore wire you can solder to the points for +v and gnd connection and make all wires as short as possible.