After doing the thermal tests, I then decided to do some voltage checks. Hard to do with the monitor still in the cabinet, so I removed the chassis, located components of interest, hooked up jumper leads to them, labeled the leads, then put it all back in the cabinet and flicked it on. I could then test each lead with a multimeter from outside the cabinet without sticking my hands in dangerous places.
Something odd I noticed is when doing the thermal camera checks, I had the game board off and only the monitor turned on, and the clicking sound would be constant. I also had no static feeling on the monitor glass.
When I was testing the voltages later on, it clicked a few times when I turned it on, and didn't click again. Now it has a slight buzz coming from the neck board and the monitor has static if I run my hand over the glass, so the flyback must be working now, right?
It no longer clicks when I turn it on. It just behaves like it's not getting a signal and still doesn't display the 'no signal' message.
Except for one round of tests where I actually got some color and very distorted blips of the 'no signal' image, but I could never make it appear again.
I can hear the tube static trickle away when I shut the monitor off, so it sounds like it is degaussing.
Have a look at my marked-up screenshot of the schematic. I've noted where I tested for voltages and the results I got. It seems to me like maybe the IC404 is my issue if you look at the voltages on their pins, and take into account the thermal image of this chip. It's very strange that I get 0V near R490, but have 11.9v at R493. I did test those resistors on-board and their values are correct, but maybe I'll pull them and see if they're still good.
Or maybe it's T401 not creating the voltage IC404 needs to operate?
Or maybe T403 isn't working and it's messing up T401?
At C432 beside T401, I get ZERO voltage. I think it's supposed to be around 18v?
I also tested the Neck Board voltages at the connectors, and compared to what the printed values said, I got:
4.98v (should be 5v)
7.19v (should be 8v)
170.2V (should be 170v)
11.93v (should be 12v)
Lastly, I tested these parts and they're good:
Q404
Q419
C432
D416
D423
R438
R440
R492
R491
I'm thinking of just getting an IC404 and slapping it in there and seeing what happens. Unless you guys have some other tests I should do to narrow this down, or suggest some other parts I should get at the same time just in case I get another domino effect.