"max" wrote in message
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My Sony Multiscan 300sf monitor suddenly died on my about 4 days ago. The
only cause I can think of is out-of-range signals, as this happened while
booting up a new Linux distro and specifying custom screen resolution. The
screen just quietly went black. So, I cycled the power on and off a
couple of times hoping to restore normal operation, but no luck.

When the unit was working properly, pressing the power button would
produce a rather loud "thunk" sound, like a heavy-duty relay being
engaged. This would be followed by a softer click, and then the video
would come on.

The thunk/hum sound is the degaussing coil energizing; the softer click is
the coil's relay disengaging (i.e., coil switched off). The degauss coil is
wrapped around the CRT face perimeter, and it's switched on with each power
up to help remove minor color impurities in the screen. Most newer monitors
have a manual degauss function, with which you can see the effect the coil
has on the screen while there's video present -- it's rather dramatic in
most cases.

Now, when I press the power button, nothing happens: the screen remains
black and there is absolutely no sound coming from it. Following some
threads I found on Google, I tried holding the - button in. After a
couple of seconds I get the familiar clicks, a loud one followed by a soft
one. While this is happening, the "Power" and "Power Saving" LEDs go
through a flashing sequence which ends with both LEDs blinking in unisson,
1/2 second on and 1/2 second off, forever. No activity on the screen
itself.

A likely culprit is in the B+ supply -- it powers the flyback xformer, which
in turn develops the high CRT screen (anode) voltage, which in turns pulls
the electron beam to the phosphor screen. An oversimplification, but a
quick Google search will get you tons of info on the subject.
You've probably got one or more bad horizontal output transistors, plus
another support component or three. Multisync monitors can have several
H-OUT xistors for the various sync frequencies used in the various graphics
modes. Since you believe you stressed the monitor out of its design limits,
this further leads me to suspect the H-OUT(s).

Designers frequently seem to protect a 10-cent fuse by having the more
costly components blow instead. Even in the unlikely event that replacing a
fuse "fixes" the problem, one should keep in mind that _something_ caused
that fuse to blow, and unless the affected components are replaced, the unit
is destined to have a subsequent and premature failure.

This is definitely not a DIY repair for the uninitiated. There are many
areas of lethal potential inside a CRT monitor, even after the unit has been
powered down for some time.