It sounds as if you've done the straightforward, logical first checks, so it's time to peel back more layers of the onion ("when you've shed enough tears, you'll be done"). It's not a bad idea to check the flyback -- instructions for doing so are given in that same document. The common failure mode for a flyback, including that one, is a shorted turn, but primary-secondary shorts are not unheard of, either.
A shorted flyback also tends to kill the BU406 horizontal driver transistor (and sometimes the transistor and logic gate that drives it), so check it, too. Be particularly suspicious if there are signs of overheating on the heatsink/tab/circuit board.
The power supply has some common failure modes. A couple of the rectifiers have a somewhat high failure rate, with the failure often showing up as a short (or low resistance). Also check the filter capacitors for leakage (both electrical and chemical).
I would also freshen up the yoke connector solder joints (I always do this whenever I open up a compact Mac, whether or not it appears to need it), as well as disconnect-reconnect the other connectors a few times to clean up the contact interfaces.
Finally -- and you should of course do this first -- perform a careful visual inspection of both sides of the analog board (I know you said you had "a good look", but that means different things to different people). Executing this simple step is surprisingly effective at finding many problems.
Good luck!
A shorted flyback also tends to kill the BU406 horizontal driver transistor (and sometimes the transistor and logic gate that drives it), so check it, too. Be particularly suspicious if there are signs of overheating on the heatsink/tab/circuit board.
The power supply has some common failure modes. A couple of the rectifiers have a somewhat high failure rate, with the failure often showing up as a short (or low resistance). Also check the filter capacitors for leakage (both electrical and chemical).
I would also freshen up the yoke connector solder joints (I always do this whenever I open up a compact Mac, whether or not it appears to need it), as well as disconnect-reconnect the other connectors a few times to clean up the contact interfaces.
Finally -- and you should of course do this first -- perform a careful visual inspection of both sides of the analog board (I know you said you had "a good look", but that means different things to different people). Executing this simple step is surprisingly effective at finding many problems.
Good luck!