TECH: Bucky O'Hare missing blue

Archived from groups: rec.games.video.arcade.collecting (More info?)

I've got a Bucky O'Hare PCB that is not outputting the color blue. This
is NOT a monitor problem as I've tried many other boards in the same
cabinet and blue is very much present on all of them except Bucky.

The output from the board at the blue pin is about .12 volts. That's
compared to a healthy range of 1.2 to 1.7 for both red and green. I can
trace the blue pin to a transistor(?) on the board, but everything
looks good. I'm new to board repair and don't know what else to look
at/for. Any help would be appreciated.

Corey

Archived from groups: rec.games.video.arcade.collecting (More info?)

I've never worked on such a board. Is it JAMMA? If it is, it's likely that
a small driver transistor has gone bad.

Three color signals come from the board: red, green and blue. On most JAMMA
boards, they use small, surface-mount transistors as a final buffer
amplifier for each signal before it goes up to the monitor. There may be a
bad solder joint; if you press lightly on the board, see if the color blue
pops back in on the monitor.

That transistor may be shorted; it happens. But it can be replaced. If
you've never done it yourself before, though, I'd recommend letting someone
else do the work. It's too easy to ruin the board.