The Punch-out that I recently obtained has a monitor issue (a monitors issue, really). Both displays are bring drawn starting ~2″ from the bottom of the monitor, and the upper few inches are being overdrawn on the same horizontal plane.
In other words, the beam is scanning left/right correctly but is starting too low and is not going high enough (vertically) to complete drawing the image correctly – the beam stops going up and keeps trying to draw the rest of the screen on the same horizontal line, causing a higher-intensity line to be seen (images below, apologies for their quality – I guess I shoulda taken off the Plexiglas first).
The overdraw is visible in the image, but it is not obvious from the images that the bottom of the image is ~2″ higher than it should be. The overdraw looks like a classic capacitor problem to me, although I admit that I am not that familiar with the “starting too high” problem and I am guessing that the two are related. At least, the two things being related kinda makes sense in my mind…
I have cap kits from The Real Bob RobertsTM (highly recommended for all kinds of arcade-related parts, BTW!) for the monitors and will be capping them shortly.
More to follow…