46 Focus Problems
Description
This article is from the comp.sys.ibm.pc.hardware.video Frequently Asked Questions, by Michael Scott with numerous contributions by others. (v1.0).
46 Focus Problems
Slight deterioration in focus can be corrected by adjusting the focus control usually located on the flyback transformer. Sometimes, this is accessible externally but usually not. On monochrome monitors, the focus control, if any, may be located on the main board.
Don't expect to have perfect focus everywhere on the screen. Usually there will be some degradation in the corners. A compromise can generally be struck between perfect focus in the center and acceptable focus in the corners.
If the adjustments have no effect, then there is probably a fault in the focus power supply.
Dead Monitor with Periodic Tweet, Tweet; Flub, Flub, or Whine:
A monitor which appears to be dead except for a once a second or so tweet or flub usually indicates a fault in the switching power supply - often a shorted rectifier.
A constant whine may mean a shorted component in the horizontal deflection circuits or elsewhere.
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