Could be a bad rectifier, or something else drawing a huge load through the connector.

Any sign of heat stress on CN2, CN3, CN4?

That's my thought as well. But I've seen bridges fail in odd ways, depending on how they fail. That and fuses are only 'close' to their rated load. So it may be drawing right at the amperage rating, or even slightly above, but not blow the fuse.

-Hans

I was thinking the same thing too, that this was the logic power.

If it's the lamp power, it's very possible it's drawing a huge pile of current if there are any shorts at a lamp socket or something on the interface board.

-Hans