Red dot after power off

matman

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I've searched for an answer to this, but can't find anything.

electrohome GO7

When i turn off my game/monitor, a fairly large bright red dot (and some green) show up on the screen and it remains there for some time. I recall this used to happen to my grandmother's old zenith tv when i was young..what is this exactly and should I be concerned?

I recently did some adjustments to the vlin, hfreq, and vheight to get my picture more centered and now when i shut the monitor off, those colors just sit there. This is all after putting in a new mainboard/neckboard that has been all recapped. (although i didn't get this red/green thing until i played with the hfreq,vlin,vheight this morning.)


thanks,
Matt
 
I've seen this in the past, and it's never harmed the monitor.

However, I did see one instance where I fixed a loose (barely hanging on) wire on the back of the focus and brightness pot and it stopped happening, but I don't know if that was the cause....
 
Here's my take on what's happening here:

When you power off, the yoke is no longer deflecting the electron beams across the tube. Their nature is to fire straight forward. They continue to emit electrons for several seconds after powering off, thus producing this lightshow in the middle of the tube. Probably because capacitors on the board are discharging.

Just speculation mind you. But it makes sense.
 
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