I just started working on an LDB that looked good on the component side, and had a bit of corrosion on the back side. That has been cleaned off and repaired. During testing, I had an abnormal number of failures - 22 of 36 of the 2N5060's were bad. I had never seen that many bad at once, so my question is: How could that have happened? I am guessing that there was a voltage spike somehow that blew those, and that the remaining 14 should be replaced since they are likely stressed and will fail soon. At that point, I am thinking its not worth replacing all of them, and just introduce the board to the trash. Thoughts?

That would make sense. I am still not sure the board is worth the effort of replacing all those components.

I don’t know the history of the board, so I can’t say for sure what happened. My guess is they did something they didn’t want to talk about.

For those who repair these boards, what have you done when you stumble across something like this?