Well after spending last night and today troubleshooting the logic board, I finally found the problem.

Without a schematic, just tracing everything out. Turns out the relay does not get its power from the output side of the voltage regulator (which is 12VDC). It just grabs it from the incoming side which is 16VDC. Uses a dropping resistor in series with the coil to allow it to operate at 12V.

Followed that all the way down to the shorting diode right before the relay coil. Still read 16V. Get to the relay, and with the TV off, fluctuating between .7 and 1.3V at random. Shouldn't be doing that as there is nothing else between the diode and relay. Shorting diode tested good. From the other side of the relay goes to the collector on the switching transistor. Turning the TV on, Base to Emitter was .7V which is right. Collector to Emitter was 0V, which is right. But still that small fluctuating voltage on the coil.

Long story short, I jumped it from the diode to relay and the TV turned on when I pressed power. Apparently there was an intermittent/bad trace on the board. I just soldered a wire in place and now everything is working fine again.




But now, the same CRT problem remains....

The TV still snapped, but not loud like in my video (which I took down because that link was unlisted and just for this site, and somebody was rather rude to me about my TV, telling me to junk it and get a Sony.)

So I let the TV run for a good while. No problems, razor sharp picture. Adjusted the purity and got that looking great. After about 15-20 minutes the tube started to snap again, about once every couple of minutes. Nothing as loud as the original video, but enough to cause the picture to jump and make you turn your head.

Went to do greyscale. Put the TV in setup mode, which is a jumper on the board. I did that with the power off. When I turned the TV on, it snapped again, and I noticed in setup line mode, the neck of the tube where the heaters are at was glowing a slight blue (looked like it was reflecting on the glass though from something further up.)

It got a little bit brighter as I watched it and it snapped again with a blue flash. Then the blue glow went away.


It started glowing blue again after a little while, and I just decided to shut the TV off. I didn't even get to do greyscale. When I shut the TV off, it snapped again, but this time a big blue flash in the neck of the tube.

Now when I was operating the TV normally without the setup line, no blue glow in the tube at all. It ran just fine for about 15 minutes, with the occasional snap here and there. Even shut down fine with no snapping.
While testing it with the test jumper earlier with the power relay problem, I just touched the lead to the relay coil and the TV came on, then I disconnected the lead, turning the TV off after I verified it worked. The TV just gave another snap a couple seconds later with no weird activity in the CRT neck.

Also to note, when I ran the TV without the second anode lead hooked up, nothing bad happened there either. This is only occurring when the HV is applied to the tube.






Just to run down a few things:
1. I cracked the tube on the old CRT. I accidentally tapped it too hard near the pins and that is what cracked it. It was already after the original CRT was beyond repair so really it was nothing to lose at that point. It wasn't up near the yoke or anything.
2. I shut down the TV in the video by pulling the plug as soon as I heard it snap. It wasn't the excessive HV shutdown protection.
3. The original CRT did not have a HV problem at all. The problem was something shorted in the neck of the tube as it affected my Sencore CRT tester. This new CRT everything tests perfect on the tester, and the TV does operate perfectly minus the occasional loud snap. I've only had this CRT on for 15 minutes total. I wasn't going to worry about that
4. What concerns me now is that blue glow and bright flash upon shutdown in the neck of the CRT when in setup line mode. Doesn't do any of that when running the TV normally.



All CRT grounds in place and hooked up. I'm just wondering what is going on here. Everything works as it should when it was on. Picture looked perfect, perfect focus, everything.
Nothing is physically burnt or blown. The CRT neckboard is fine. Picture was the right size and everything.


These are just all things I've never seen before. I got my HV probe, just haven't tested the TV with it yet. I don't suspect that being a problem though. Focus is right in the center of the pot as well.

I am just hoping this NOS CRT is just being funky and will eventually quit doing that. I just can't explain why it was glowing blue in setup line mode like that with a another snap/blue flash in the neck when I shut it down, other than the fact that vertical deflection is shut down (hence the electron beam being concentrated and extra bright), and there is no luminance/chrominance signal present.
This TV has sentimental value to it, and that's why I really want to get it going again.

I did turn it back on after all this in normal mode, and it did not snap one time at all. Picture came up beautifully, no blue glowing. I am so hoping this CRT is just being weird. I just didn't get to do greyscale (which isn't too far off from the old tube, just a little bit reddish at low light). Drives are dead on. I'm wondering if I should just let it run for several hours, get broken in first.
Last new CRT set I bought was in 1996. It did snap a lot (just not like this TV is doing) for about a couple weeks until it broke in. Then it hardly ever did it after that.

It's late and I'll play with this some more tomorrow.

Because after I perfect the greyscale, convergence and purity, this TV should be ready for semi-daily use like I plan to use it for (retro video gaming and being hooked up to the CATV system and Sanyo Betacord VCR).