I have a Compaq s910 which works fully except for a clicking sound from it
when the monitor enters standby mode. What I know so far is that the
clicking is just the degauser relay (nothing arcing). The monitor can only
enter standby mode for a split second before powering up the transformer
and tube etc, then a split second later goes back to standby mode and
repeats the process forever.

There is a IC (3843B) on the board which is cauing the main transformer to
kick in, but don't know if its the problem or just a side effect. I have
measured voltages from around the place and firstly have to say that I
don't understand how the aforementioned IC can even function in that AC
enviroment.

I have got the schematics for everything. The important bits:

http://members.iinet.net.au/~quadfour/3842B-3843B.pdf - IC schematics
http://members.iinet.net.au/~quadfour/s1494-1.pdf - s910 PSU schematics
http://members.iinet.net.au/~quadfour/temp.jpg - shows some voltages
I've found.

The schematics of the 3843B mentioned voltages well below the ~140AC I am
seeing on its side of the transformer. Together with that I don't have a
solid grasp on this (enough to replace components).

Any ides on how to pinpoint the reason for the 3843B turning everything on
after a split second of the monitor being in standby mode?

Cheers
Michael