Hi,

My 4 or 5 year old Eizo T766 19" CRT began showing an intermittant fault
yesterday. Sometimes the screen contracts a bit and comes back with wrong
colors. An example is that the screen turns very blue, and you can see the
diagonal vertical retrace lines in blue running over the screen (at least, I
assume they are the retrace lines). When the screen snaps back, it's often too
greenish, but turns normal over the course of a few minutes.

I had it open yesterday, and a couple of times, I could reproduce the fault by
touching the cathode assembly, so I thought it was a physical error, like a
loose contact. And just now, when it did it again, the monitor responded to me
hitting it (gently...). But, I couldn't reproduce it consistently, yesterday
or now.

I have a couple of questions.

1) A couple of times, the fault caused the monitor to go into off mode. At
least, the power led turned yellow, which it normally does in offmode. Is it
likely that when the fault is somewhere in a late stage as the cathode
assembly, that the control electronics is aware of it?

2) Should I want to refit the plugs connected to the cathode assembly (three
big wires; are those the RGB line voltage wires?), I would need to discharge
the CRT. I've seen a lot of videos of people just sticking a screwdriver
connected to the metal chassis under the anode plug, but is that safe? I've
never discharged a CRT before, so I'm kind of apprehensive.

3) How vital is it to discharge the power supply caps? If so, how does one do
that?

Any other insight is welcome, of course.

Thanks in advance,

Wiebe Cazemier