I recently picked up an IIsi off the local classifieds as a project, knowing it (and the PSU) will need a recap. Someone had already done the 50mhz oscillator upgrade, so that was a plus - until I cleaned the board and started inspecting it. When I turned it over I saw corrosion around the pins of the oscillator, the rest of the board is spotless. I used a q-tip and IPA to clean the corrosion off and was dismayed by what I saw. Whoever did the upgrade had no idea what they were doing, it looks to me like they probably left corrosive flux on the board and it damaged the PCB, as seen in the attached photos.
I'm hoping the board is still ok. I got out the Bomarc schematic and used my meter to check continuity on the three pins (the fourth doesn't go anywhere), and it looks ok. One goes to power, one to ground, and one to pin 107 on the MDU. I'm hoping that no corrosion worked its way further into the board and affected any of the other layers. I'm inclined to just leave it alone, I don't want to cause any further damage by removing the oscillator for inspection.
Sometimes you learn a lesson the hard way, even if it's through someone else's actions!
I'm hoping the board is still ok. I got out the Bomarc schematic and used my meter to check continuity on the three pins (the fourth doesn't go anywhere), and it looks ok. One goes to power, one to ground, and one to pin 107 on the MDU. I'm hoping that no corrosion worked its way further into the board and affected any of the other layers. I'm inclined to just leave it alone, I don't want to cause any further damage by removing the oscillator for inspection.
Sometimes you learn a lesson the hard way, even if it's through someone else's actions!
