Re: Monitor - Horizontal Shift

["Michael J. Mahon" <mjmahon@aol.com>]

Vince Briel wrote:
> Make sure you use extreme caution when checking inside the monitor as they 
> can hold high voltage even if they have been off for a while (I'm living 
> proof, it hurts). Which model do you have? Some not only have external 
> adjustment but internal as well.
>
> Have you tried attaching a standard TV signal into it to see if it has the 
> same issue?

Good point--or just turn up the brightness until you can see the edge(s)
of the raster.

It is important to distinguish between a timing problem--raster
centered, but video offset--and a positioning problem--raster
offset.  The horizontal hold control can often adjust the
horizontal phase (timing) by about 10% of the width (though it
should generally be set near the center of its lock range).

If the raster is offset, very few monitors have a pot to control
this.  They usually use a pair of ring magnets that can be turned
concentric with the neck of the CRT at the rear of the deflection
yoke.

By adjusting their relative angle, you control the resultant
strength of the magnetic field, and by rotating both together
you control the direction of displacement of the raster.  This
allows the raster to be centered.

The monitor must be operating to make this adjustment, so if
you are not comfortable working on an open, operating monitor,
it's a job best left to a TV repair place (if they still exist).

-michael

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