I'm quoting JDW from an older post he had on AppleFritter:

"I have also read about replacing the bourns chip (RP2), but I don't have one handy and I honestly do not see the logic behind that either. Looking at the schematic of that area, you can see that bourns chip is simply filtering the signals from the leftmost serial port and passing them through to another chip on the board. But if nothing is plugged into that particular serial port, the bourns chip is not used (from what I see) and therefore I cannot see how replacing the bourns chip would cure SimasiMac."

I don't have a SimasiMac but if the bourns chip is simply filtering signals I'm not sure how that would keep the Mac from booting. Either way, I just sent you another PM. And as always - thanks for the help!