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Nice to see some team building on the forum. I know, some of us are allergic to letter fungus, but I put together a neat top 10 list I wanted to share. Hey, feel free to modify it. But this one I always find fun to do. Except step 10 gets to be a bit of work. But, at any rate, here goes. So, as another member mentioned glowing white dot after the set is turned off is a good sign that you have (some) emission and (some) high voltage. Here's a few tricks I learned years ago.
1) Examine the neck of the CRT. If the Cathode and G1 are crooked at a noticable angle about 30 deg then you probably need an ION trap.
2) Turn off all lights in the room (do this at night) and let you eyes get used to the dark for about 15 minutes.
3) Turn on the set and let it warm up for a few minutes then turn it off to get the white dot.
4) If an ION trap is needed you need to figure out the best position and what impact it may have on brightness. Need to experiment a bit.
5) With your eyes acquainted to the dark the white dot will appear brighter to you. Slip the ION trap over the CRT socket onto the end of the tube and gradually slide it up the tube. Rotate slowly as you slide. Constantly watch how the brightness of the dot varies.
6) There should be a point where the maximum dot brightness appears on the screen. Leave the ION trap in this position.
7) Turn the set back on. Turn the brightness control OFF. Turn contrast to MID position. Tune in a station, hoepfully you'll get sound. If you can tune in a station then great! But if you can't ..don;t fuss. Just you blank raster for the next step.
8) Slowly increase the brightness and observe the screen carefully for raster. Inter play contrast and brightness controls. Most situations boil down to 2 conditions usually: a) weak HV and b) low emission. If HV is weak then setting the birghtness too high causes the HV to reduce (can't supply enough current) and the picture blooms until you can't see it. In the low emission case, brightness or contrast may bias the tube off. Watch for tell-tale 'negative picture' as the brightness or contrast begins to push the CRT into saturation. In some case you can bias off the CRT if misadjusted.
9) If you still can't get anything then try checking CRT emission with a CRT checker. But a CRT tester may not tell the truth, especially with older ION trap tubes and weak emission. I know some ION trap tube that don't show any emission on my B&K yet still produce marginally weak, but watchable, pictures.
10) All else fails there may be a circuit issue that's causing the CRT to bias off when the set is operating. Roll up your sleeves and get out the 'ol scope probe and start hunting!
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