Thought I'd get some thoughts..

The LN2805 (column driver) seems to be dying, and taking the +!2v circuit with it. However, on average now, it's only happened twice now, and there was a 2-week delay between the first time and now, the second time. Last time, whatever happened killed the address chip up-stream (LS374) on column 3, so it was replaced as well.

The ball was in a different location each time - the last time I had just shot the piano. This time, I shot the right-ramp to the diverter. So I'm wondering if it's possible a cap (C11-C18) is possibly dying/shorting out (don't think so, since then that would just activate the whole column..) or one of the prox / opto boards should be looked at. (They're all original to the game, 23 years ago. )

I forgot to mention - this time, the address chip, col 6 was stuck low (no pulsing of the column driver). This is likely just a causation of the 2803 getting blown, and not an indication that col 6 was the one that got shorted to voltage, since last time it was col 3.

However, if a high-current (+20, +50, etc) got shorted to a col, I'm a little fuzzy an how that would blow my +12v fuse. Wouldn't the 1k res along the column protect that from drawing too much current off of the +12v regulator?