Got A view sonic moniter A70F that the picture is sharp as can be. about 45sec later at the snap of a finger way out of focus. then about a min later sharp as can be again. instant out and in of focus. does this cold or hot all day. not a bad solder joint for hitting/tapping the moniter does nothing. not a slow drift its instent. any clue???. I would like to fix it not buy a new one. any clue Guys.
Thanks for any help or idea you guys may have.
DAVE
Probably either a bad flyback transformer or bad tube.
The focus adjustment is probably a pot which is an integral part of the line output transformer, and it could be that this pot is causing the problem. Try cleaning it by spraying with contact cleaner and then turning it rapidly back and forwards (with the monitor off, of course). Afterwards turn the monitor on and set up the focus with the pot - take care, though, there are some very high voltages around that area.
The glue holding the focus pot may have let go, allowing the pot to wiggle a bit.
Tom
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