Neotec Chungwa picture tube swap

Mongo

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Here is the story:

I have a couple of Neotec 19" VGA monitors with perfect picture tubes. I have a rebuilt G07 that is not quite as brite as I would like. There are no stickers on the picture tubes to identify what they are so I decided to take a chance and attempt a swap.

I swap the yoke and convergence purity rings from my G07 tube to the Neotec tube and fire it up. The picture is near perfect with no adjustment...... for about 5 seconds. After 5 or so seconds I get a quickly increasing in volume feedback "buzz" coming out of the game speakers and distortion lines horizontally in the center 3 inches of the screen pulsating with the ever increasing noise. I shut down the game, wait a few seconds, and power it back up. Exact same thing. A few seconds of good picture followed by a loud buzz from the game and distortion on the screen. I have no idea what would blow up if I let it go but I get the feeling something will.

Does this point to the picture tube being completely incompatible? Seems like an obvious question and answer but I was under the impression that if it were incompatible I would get no picture and immediate smoke and fire....
 
Looks like it is fixed

So, I went out to the garage and got ready to swap in a different tube. I pulled out the ol' HV probe and started to discharge the Chunghwa tube. Rather than a quick "snap" I got the slow bleed off buzz.... and it just kept going and going and going..... The thought occurred to me that there should not be a FULL charge left in the tube... at least SOME of it should have bled off to ground. And come to think of it, the building sound in the game speakers could have been power from the monitor bleeding back through the power circuit looking for another path to ground....

Before pulling the tube completely I decided to give it another chance and re-run my grounds with additional alligator clips. One from the chassis to the game ground, one from the DAG spring to the neckboard, and tighten the loose screws on the monitor ears to the chassis. Powered it up and the buzz is gone and the picture is pretty great! Not perfect yet but I am sure it will be when I finish my adjustments!
 
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