blurry monitor....

[greenman100]

....are there internal adjustments for the sharpness of a monitor?

[SK8]

no, it just means that one of the caps is going bad. aka, time to get a newone or rma it. I suggest not messin with the internals.

[greenman100]

no, it just means that one of the caps is going bad. aka, time to get a newone or rma it. I suggest not messin with the internals.


I have 15kV gloves and am a mechanical engineer, just need to know if the adjustment is there

[SK8]

Certifications dont mean much when you get zapped to death. I would try to rma before looking into opening it.

[greenman100]

Certifications dont mean much when you get zapped to death. I would try to rma before looking into opening it.

ok, point taken and disregarded, not the subject at hand.

I can't RMA it, I found it next to a dumpster

[Enablingwolf]

Credit to: repairfaq.ece.drexel.edu

Some monitors have the focus adjustment accessible through a (possibly
unmarked) hole in the side or rear of the case. If there is a single
hole, it is almost certainly for overall focus. If there are two holes,
one may be the screen (G2 - master brightness) or the two adjustments may
be for different aspects of focus (e.g., horizontal and vertical). Just
carefully observe what happens when each adjustment is moved a little so
that you can return it to its original setting if you turned the wrong one.
Use a thin insulated screwdriver - preferably with a plastic blade. As
a extra precaution, determine of the screwdriver will mate easily with the
adjustment with the monitor **off** (don't turn anything, however).

Where there are two adjustment knobs on the flyback transformer, the top one
is generally for focus and the bottom one is for G2.

Most inexpensive monitors have only what is known as static focus - a constant
voltage derived from the HV power supply is applied to the focus grid of the
CRT. This does not allow for optimal focus across the screen and any setting
is just a compromise between central and edge sharpness.

Better monitors will have (in addition) H and V focus controls. These are
for dynamic focus adjustments. There may be some interaction between the
static and dynamic adjustments. If either of these controls has no effect or
insufficient range, then there may be a fault in the circuitry for that
particular adjustment - a fault with the driver, waveform source, power
supply, etc. The most sophisticated schemes use a microprocessor (or at least
digital logic) to specify the waveform for each section of the screen with a
map of correction values stored in non-volatile memory. It would be virtually
impossible to troubleshoot these systems without detailed service information
and an oscilloscope - and even then you might need a custom adapter cable and
PC software to adjust values!


If you need to go inside to tweak focus pots:

Safety: as long as you do not go near anything else inside the monitor while
it is on AND keep one hand in you pocket, you should be able to do this without
a shocking experience.

Plug it in, turn it on and let it warm up for a half hour or so. Set your
PC (or other video source) to display in the resolution you use most often.
First turn the user brightness and contrast fully counterclockwise. Turn
brightness up until the raster lines in a totally black area appear, then
back a hair until they disappear. Then, turn the contrast control up until
you get a fairly bright picture. Fullly clockwise is probably ok. Adjust
FOCUS for generally best focus. You will not be able to get it razor sharp
all over the screen - start at the center and then try to get the
edges and corners as good as you can without messing up the center too much.
Double check that the focus is ok at your normal settings of brightness and
contrast and at other resolutions that you normally use.

The focus pot is usually located on the flyback transformer or on an
auxiliary panel nearby. The focus wire usually comes from the flyback or
the general area or from a terminal on a voltage the multiplier module
(if used). It is usually a wire by itself going to the little board
on the neck of the CRT.

The SCREEN control adjusts background brightness. If the two controls are
not marked, you will not do any damage by turning the wrong one - it will
be immediately obvious as the brightness will change rather than focus
and you can then return it to its original position.

On a decent monitor, you should be able to make out the individual scanning
lines at all resolutions though it will be toughest at the highest scan rates.
If they lines are fuzzy, especially in bright areas, then focus may need
to be adjusted or there may be an actual fault in the focus circuitry or
a defective or just marginal CRT.

[greenman100]

opened it up, 2 adjs for focus, now good as new

[CPUonNO2]

opened it up, 2 adjs for focus, now good as new
Gotta love it when that happens